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GEHS Neurophysiological Classification System for Patients with Neuropathy of the Ulnar Nerve at the Elbow.

Neuropathy of the ulnar nerve at the elbow is one of a number of muscle-related and nervc-related disorders that affect people performing intensive work with their hands and upper extremities, and is the second most prevalent peripheral nerve mononeuropathy. (1-7) There are several classification systems currently used by the medical community for patients with neuropathy of the ulnar nerve at the elbow. (6-12) However, few of these classification systems include the clinical electrophysiologic parameters nerve conduction (NCS) and electromyographic (EMG) studies.

The ulnar nerve is comprised of the anterior primary rami of the C8 and T1 nerve roots. (13-14) In the inferior neck at the level of the anterior and middle scalenes, the C8 and T1 nerve roots form the inferior (lower) trunk and then each trunk of the brachial plexus divides into the anterior and posterior divisions as the plexus passes through the cervico-axillary canal posterior to the clavicle. (13-14) The anterior divisions of the trunks supply anterior (flexor) compartments and posterior divisions supply posterior (extensor) compartments. The anterior division of the inferior trunk continues as the medial cord. (13-14)

The ulnar nerve is the terminal nerve of the medial cord and lies in the anterior compartment of the arm. Proximal to the elbow joint, the ulnar nerve passes into the posterior compartment of the arm and descends between the medial epicondyle of the humerus and olecranon process of the ulna to form the ulnar groove. (13-14) Similar to the median nerve, the ulnar nerve docs not give rise to branches during its passage through the arm. In the forearm, the first musclc innervated by the ulnar nerve is the flexor carpi ulnaris (FCU) followed by the ulnar half (ring and little finger) of the flexor digitorum profundus (FDP D4-D5). After sending motor branches to the FCU and FDP D4-D5, the ulnar nerve continues distally, ultimately terminating into 3 primary distal branches; (1) dorsal ulnar cutaneous nerve; (2) superficial branch of the ulnar nerve; and (3) deep motor branch of the ulnar nerve. The dorsal ulnar cutaneous branch typically bifurcates from the ulnar nerve about 5 cm proximal to the ulnar styloid process and proceeds dorsally and distally to innervate the skin on the dorsum of D5 and the ulnar aspect of D4, along with the adjacent skin over the dorsum of the hand, providing sensation to the skin of that region. (13,14) Apart from this branch, the bulk of the ulnar nerve passes through the ulnar canal (Guyon's canal) at the wrist and divides into a superficial branch which provides motor innervation to the palmaris brevis and skin sensation to the palmar surface of D5 and medial half of D4.1314 The deep motor branch of the ulnar nerve then innervates the hypothenar muscles (abductor digiti minimi, flexor digiti minimi, and opponens digiti minimi), lumbricale muscles to D4 and D5, and the ulnar intrinsics including the dorsal and palmar interassei and adductor pollicis. (13-14)

There are 5 anatomic sites of ulnar nerve compromise at the elbow: (1) intermuscular (IM) septum of the distal arm (including the Areade of Struthers, medial IM septum, hypertrophy of medial head of triceps brachii, and snapping of medial head triceps brachii); (2) medial epicondylc secondary to a valgus deformity of the bone; (3) epicondylar groove (lesions within and outside of the groove and subluxation or dislocation of the nerve); (4) cubital tunnel (due to a thickened Osborne's ligament, a fibrous fascia running between the humeral and ulnar heads to the FCU) or as the nerve passes through the proximal edge of the FCU; and (5) as the ulnar nerve exits through the FCU. (4)

In a review of the clinical, electrodiagnostic, and radiographic features of ulnar neuropathy at the elbow, Landau and Campbell (5) found that there are 3 main sites of ulnar nerve compromise at the elbow: (1) retrocondylar groove, proximal to the medial epicondyle/olecranon; (2) humcro-ulnar aponeurotic areh including cubital tunnel syndrome and as the ulnar nerve passes between the areuate ligament spanning the two heads of the FCU; and (3) flexor/pronator aponeurosis as the ulnar nerve exits from beneath the FCU. They stated that the etiology of neuropathy of the ulnar nerve at the elbow is most commonly due to lesions at the level of the ulnar nerve at the retrocondylar groove at or above the medial epicondylc/olecranon with only 25% occurring distally at the humero-ulnar areade. (5) Furthermore, they suggested that maintaining across-elbow measurements (above elbow to below elbow) greater than 10 cm improves the diagnostic specificity at the expense of decreased sensitivity of accessing ulnar neuropathy at the elbow. (5)

GEHS Neurophysiological Classification System for Patients with Neuropathy of the Ulnar Nerve at the Elbow

A thorough history and physical examination are considered essential screening tools for detecting signs and symptoms of peripheral neuropathy. (1-3) Nerve conduction measurement is often performed on the ulnar nerve to determine whether certain entrapment neuropathies are present, and nerve conduction studies are considered the gold standard by providing criterion-related validation when assessing the electrophysiological status of the peripheral nerve. (1-3) The electrophysiological examination including both nerve conduction and electromyography studies should identify peripheral nerve dysfunction if present, along with the specific location in the nerve pathway, involvement of sensory and/or motor axons, and the presence of myelinopathy and/or axonopathy neuropathic process. (1-3)

Nerve conduction studies and EMG testing have the advantage of providing potential electrophysiological evidence of pathological conditions of the ulnar nerve including dcmyelination (myelinopathy) and axon loss (axonopathy). (1-3) In 2015, a new neurophysiological classification system for patients with neuropathy of the ulnar nerve at the elbow was introduced. The GEHS (Grcathousc, Ernst, Halle, Shaffer) (15) neurophysiological classification system for patients with neuropathy of the ulnar nerve at the elbow is comprised of data from both the NCS and EMG components of the electrophysiological examination. The GEHS neurophysiological classification system for patients with neuropathy of the ulnar nerve at the elbow, presented in Table 1, provides healthcare providers an enhanced system of electrophysiological evaluation and grading scale so that they may evaluate and treat their patients with this problem using data that includes both NCS and EMG testing results.

Furthermore, this new system provides information which includes specific abnormal findings of sensory and/or motor axons and myelinopathy and/or axonopathy. The GEHS neurophysiological classification system for patients with neuropathy of the ulnar nerve at the elbow is presently being used by clinical electrophysiologists and has been cited in various research reports. (16-19)

This article describes application of the GEHS neurophysiological classification system for patients with neuropathy of the ulnar nerve at the elbow in 2 case studies of patients with electrophysiological evidence of the disorder.

Case Studies

Case 1

A 42-year-old right-hand dominant male was referred by his primary care physician for electrophysiological evaluation of a suspected left ulnar nerve neuropathy. The patient is a computer software developer. In 2015, he noted intermittent pain and numbness and tingling (N/T) in the left upper extremity (LUE). The patient had no past medical history of problems affecting cither upper extremity and denied recent trauma to the neck or either upper extremity. The symptoms in the LUE increased over the month preceding presenting for evaluation. He had pain in the left elbow, medial forearm, wrist, and digits 4 and 5 (ring and little finger; D4-D5). Otherwise, he had no other pain in the LUE. The patient states he had N/T in the palmar and dorsal surfaces of the left D4-D5, but otherwise denied N/T proximal to the wrist in the LUE. The patient denied weakness in the LUE, including hand and digit movements. The patient denied pain, N/T, or weakness in the right upper extremity (RUE) and had no symptoms in cither lower extremity. The patient had some stiffness in neck movements but no neck pain or radicular symptoms in cither upper extremity. He denied history of headaches, visual or cranial nerve problems.

The patient was slightly overweight and is hypertensive (on medication), but otherwise is in good health. The review of systems was noncontributory for cardiovascular, pulmonary, gastrointestinal, genitourinary, or endocrine problems. He denied having diabetes, heavy metal exposure, thyroid disease, renal disease, or alcohol abuse, and has no family history of neuromuscular disease.

The patient was evaluated in January 2017. On physical examination, the patient displayed normal active cervical mobility in all planes without neck pain or pain in both upper extremities (BUE). The Spurling's test did not provoke pain in the neck or in cither upper extremity. He had normal active mobility of bilateral shoulder, elbow, forearm, wrist, and hand motions. The patient had weakness in the left ulnar hypothenar and intrinsic muscles (3+/5) and the left FDP digits 4 and 5 (3+/5). There was normal (5/5) motor strength of the left FCU, abductor pollicis brevis (APB), opponens pollicis, flexor pollicis longus (FPL), flexor digitorum profundus D2D3 (index and middle fingers), extensor indicis, and extensor pollicis longus (EPL). In addition, there was normal (5/5) motor strength testing of bilateral shoulder, elbow, forearm and wrist motions; and right hand motions. There was no atrophy or clonus noted in BUE. The biceps, triceps, and brachioradialis muscle stretch reflexes were present and equal in BUE. The Hoffman reflex was absent in both hands. There was a decreased sensation to light touch (LT) and pain (pin prick) in the dorsal and palmar surfaces of the left ring (D4) and little (D5) fingers. Otherwise, sensory testing was normal for LT and pain in BUE, including all peripheral nerves and dermatomes (C4-T1). There was a positive Tinel's test of the left ulnar nerve at the elbow, but otherwise the Tinel's and Phalen's tests were negative for bilateral median and ulnar nerve involvement at the wrists or elbows. There were normal radial pulses bilaterally for thoracic outlet syndrome in the scalene, costoclavicular, and pectoralis minor/clavipcctoral fascia humeral maneuvers.

Results of the NCS and EMG studies for case study 1 are presented in Tables 2 and 3, respectively. Clinically noteworthy NCS and EMG abnormal findings are indicated by shaded cells in Tables 2 and 3.

In conclusion of case study 1: this was an abnormal NCS and EMG study of the LUE and a normal NCS study of the RUE. There was electrophysiologic evidence on this examination of a severe, left ulnar nerve mononeuropathy at the elbow, at or distal to the medial epicondyle/ olecranon and distal to the innervation of the FCU; demyelinating and axonal loss neuropathic process affecting both motor and sensory fibers; and chronic denervation of the left first dorsal interosseous (1st DI) and abductor digiti minimi (ADM). Electromyographic testing of the left FCU and other muscles tested in the LUE was normal. There was no electrophysiologic evidence on this examination of (1) right ulnar nerve mononeuropathy; (2) bilateral median or superficial radial mononeuropathy, including the left median nerve at or distal to the wrist; (3) left C5-T1 radiculopathy in the LUE (cervical paraspinal muscles not tested); and (4) left brachial plexopathy, including the medial cord and inferior trunk.

Based on the above ease study 1 results, the GEHS neurophysiological classification system category was severe mononeuropathy of the left ulnar nerve at the elbow. There was a prolonged left ulnar palmar distal sensory latency (DSL) (5.6 ms, normal <2.2) with a normal amplitude of the sensory nerve action potential (SNAP) (15 [micro]V). There was no sensory response for the left ulnar 5th digit (D5) when tested orthodromically or antidromically. There was a normal left ulnar distal motor latency (3.5 ms), but the amplitude of the compound motor action potential (CMAP) was reduced at 4.3 mV (normal >5). The motor nerve conduction (MNCV) of the left ulnar nerve in the forearm (below elbow (BE) to wrist) was reduced at 46 m/sec (normal >50) with a reduced CMAP amplitude of 2.1 mV (normal >5) at the BE stimulation site. The MNCV of the left ulnar nerve at across the elbow (above elbow to below elbow (AEBE)) was normal (54 m/sec) with a reduced amplitude CMAP of 4.5 mV (normal >5). On EMG examination, there was increased insertional activity and the presence of abnormal spontaneous electrical activity at rest in the left 1st DI and ADM with a 50% reduction in interference patterns during maximum voluntary contraction in both of these muscles. Since EMG findings were demonstrated in 2 of the 4 muscles outlined in the "Severe" section of Table 1, EMG of all 4 of the muscles outlined in Table 1 was not performed. In this case, obtaining EMG of the FDP to D4 and D5 was deferred. There was normal EMG testing of the left FCU, APB, FPL, EPL, and other muscles tested in the LUE. These findings are electrophysiological evidence of both a demyelinating and axonal loss neuropathic process of the left ulnar nerve at the elbow.

Case 2

A 48-year-old right-hand dominant male was referred by his orthopaedic surgeon for electrophysiological evaluation of a suspected right ulnar nerve neuropathy. The patient is a pool repair technician. In 2015, he noted intermittent pain and N/T in the RUE. The patient had no past medical history of problems affecting cither upper extremity and denied recent trauma to the neck or cither upper extremity. The symptoms in the RUE increased over the month preceding presenting for evaluation. He had pain in the right elbow. Otherwise, he had no other pain in the RUE. The patient states he had N/T in the palmar and dorsal surfaces of the right D4-D5 (ring and little fingers), but otherwise denied N/T proximal to the wrist in the RUE. The patient denied weakness in the RUE including hand and digit movements. The patient had occasional N/T in the dorsal and palmar aspects of the left D4-D5 but otherwise denied pain, N/T or weakness in the LUE and had no symptoms in cither lower extremity. The patient denied neck pain or radicular symptoms in cither upper extremity. He denied history of headaches, visual or cranial nerve problems. The patient is on medication for hypertension but is in good health. Otherwise, the review of systems was noncontributory for cardiovascular, pulmonary, gastrointestinal, genitourinary, or endocrine problems. He denied having diabetes, heavy metal exposure, thyroid disease, renal disease, or alcohol abuse, and has no family history of neuromuscular disease.

The patient was evaluated in May 2016. On physical examination, the patient displayed normal active cervical mobility in all planes without neck pain or pain in BUE. The Spurling's test did not provoke pain in the neck or in cither upper extremity. He had normal active mobility of bilateral shoulder, elbow, forearm, wrist, and hand motions. The patient had weakness in the right ulnar hypothenar and intrinsic muscles (3+/5), right FDP D4 and D5 (ring and little fingers) (3+/5), and right FCU (4/5). There was normal (5/5) motor strength of the right APB, opponens pollicis, FPL, flexor digitorum profundus D2D3 (index and middle fingers), extensor indicis, and EPL.

In addition, there was normal (5/5) motor strength testing of bilateral shoulder, elbow, forearm and wrist motions; and left hand motions. There was no atrophy or clonus noted in BUE. The biceps, triceps, and brachioradialis muscle stretch reflexes were present and equal in BUE. The Hoffman reflex was absent in both hands. There was a decreased sensation to LT and pain (pin prick) in the dorsal and palmar surfaces of the right ring (D4) and little (D5) fingers. Otherwise, sensory testing was normal for LT and pain in BUE including all peripheral nerves and dermatomes (C4-T1). There was a positive Tinel's test of the right ulnar nerve at the elbow, but otherwise the Tinel's and Phalen's tests were negative for bilateral median and ulnar nerve involvement at the wrists or elbows. There were normal radial pulses bilaterally for thoracic outlet syndrome in the scalene, costoclavicular, and pectoralis minor/clavipectoral fascia humeral maneuvers.

Results of the nerve conduction and electromyography studies for case study 2 are presented in Tables 4 and 5, respectively. Clinically noteworthy NCS and EMG abnormal findings are indicated by shaded cells in Tables 4 and 5.

In conclusion of ease study 2: this was an abnormal NCS and EMG study of the RUE and a normal NCS study of the LUE. There is electrophysiologic evidence on this examination of a severe right ulnar nerve mononcuropathy at the elbow proximal to the olecranon/medial epicondyle and proximal to the innervation of the right FCU; axonal greater than dcmyclinating neuropathic process affecting motor and to a lesser extent sensory fibers; and a mixture of acute and chronic denervation in the right 1st Dl, ADM, and FCU. There was no electrophysiologic evidence on this examination of (1) left ulnar nerve mononeuropathy; (2) bilateral median or superficial radial mononeuropathy, including the right median nerve at or distal to the wrist; (3) right C5-T1 radiculopathy in the RUE (cervical paraspinal muscles not tested); and (4) right brachial plexopathy, including the medial cord and inferior trunk.

Based on the above case study 2 results, the GEHS neurophysiological classification system category was severe mononeuropathy of the right ulnar nerve at the elbow. There was a prolonged right ulnar palmar DSL (2.3 ms, normal <2.2), with a normal amplitude of the SNAP (17 [micro]V). The right D5 (little finger) DSL latency was normal (3.5 ms) with a normal amplitude of the SNAP (12 [micro]V). There was a prolonged right ulnar distal motor latency (3.8 ms, normal <3.6), but the amplitude of the CMAP was normal (7.5 ms). The MNCV of the right ulnar nerve in the forearm (BE to wrist) was normal at 53 m/sec (normal >50), with a normal CMAP amplitude of 7.2 mV (normal >5) at the BE stimulation site. The MNCV of the right ulnar nerve at AE-BE was reduced (45 m/scc, normal >50) with a reduced but normal amplitude CMAP (6.4 mV) at the AE stimulation site. The MNCV of the arm (axilla to AE) was normal at 74 m/sec with a normal CMAP amplitude of 7.0 mV. On EMG examination, there was increased insertional activity and the presence of abnormal spontaneous electrical activity at rest in the right 1st Dl, ADM, and FCU, with a 75% reduction in interference patterns during maximum voluntary contraction in the right 1st DI and ADM. Since EMG findings were demonstrated in 3 of the 4 muscles outlined in the "Severe" section of Table 1, EMG of all 4 of the muscles outlined in Table 1 was not performed. In this case, obtaining EMG of the right FDP to D4 and D5 was deferred. There was normal EMG testing of the right APB, EPL, and other muscles tested in the RUE. These findings are electrophysiological evidence of both a demyelinating and axonal loss neuropathic process of the right ulnar nerve at the elbow.

Comment

The advantage of having information regarding NCS and EMG changes (myelinopathy and axonopathy) for patients with neuropathy of the ulnar nerve at the elbow is that it provides the healthcare team and the patient with information that may be useful in determining next treatment steps as well as long-term prognosis. Nerve conduction studies provide assessment of the peripheral nerve being examined, especially as it relates to myelination or demyelination and location of the site of nerve compromise. In the case of a patient with EMG changes, the combined effects of compression and ischemia are evident with the loss of a subset of axons and the denervation of a segment of the innervated muscle fibers. (1-3) The EMG examination specifically provides information regarding motor fiber denervation as confirmed by the presence of increased insertional activity and abnormal resting potentials (eg, positive sharp wave, fibrillations potentials). Additionally, EMG examination provides the healthcare team with information regarding the presence, morphology, and recruitment pattern of motor units that is critical for determining the extent of motor fiber involvement and if reinnervation (polyphasic or large motor potentials) is truly occurring. (1-3) Collectively, the EMG examination affords critical motor fiber neurophysiologic information that allows the healthcare team, in concert with the patient, to carefully consider interventions. (1-3)

There are several classification systems for patients with neuropathy of the ulnar nerve at the elbow currently being used by the medical community. (6-12,20-22) However, few of these classification systems include clinical electrophysiologic parameters (eg, nerve conduction and electromyographic studies). Ulnar nerve at the elbow neuropathy severity scales based on the patient's subjective (paresthesia and pain) and physical examination findings (sensory and motor strength changes) place the patient into groups, (6) scales, (20-22) or grades (21) based on the severity of symptoms and findings on physical examination. The Patient-Rated Ulnar Nerve Evaluation (PRUNE) was developed to assess pain, symptoms, and functional disability in patients with ulnar nerve compression at the elbow. (7) The PRUNE is a patient-reported outcome measure for patients with ulnar nerve compression that demonstrates strong measurement properties. (7) Decisional algorithms have been developed for patients with neuropathy of the ulnar nerve at the elbow to assist in selecting the surgical procedure for ulnar nerve entrapment (9) and to identify predictors of surgical outcomes. (10)

In a study based on electrophysiologic assessment of the ulnar nerve, Eliaspour et al (8) determined the pattern of muscle involvement in patients with ulnar neuropathy at the elbow. Muscle involvement in patients with neuropathy of the ulnar nerve at the elbow included 1st DI (91.9%), ADM (91.3%), FCU (64.9%), and FDP D4-D5 (56.8%). Using a Baycsian analysis, Logigian et al (23) determined how electrodiagnostic cutoffs (eg, across-elbow MNCV slowing and drop in across-elbow versus forearm MNCV) assist in assessing patients with ulnar nerve at the elbow neuropathy. They determined that above elbow to below elbow distances and stimulation sites should be at least 10 cm. Pretest probability was determined at 0.25 (if there is a greater than 23 m/ sec difference between above elbow to below MNCV compared to the below elbow to wrist MNCV, and/or an above elbow to below elbow absolute MNCV value of less than 38 m/sec. (23) A less conservative retest probability of 0.75 was also determined (difference greater than 14 m/sec, and an absolute AE-BE MNCV value less than 47 m/sec, respectively). (23) In a study comparing the prognostic value of electrodiagnostic studies for patients with ulnar neuropathy at the elbow and their postsurgical results, a combination of conduction block across the elbow to the 1st DI and a normal distal compound muscle action potential amplitude from the ADM was strongly associated with recovery in patients. (24) Friedrich and Robinson concluded that electrodiagnostic studies provide useful prognostic information in ulnar nerve at the elbow neuropathy, but there are no electrodiagnostic predictors of surgery. (24)

Although the GEHS classification scheme provides a framework for reporting and categorizing neuropathy of the ulnar nerve at the elbow based on neurophysiology findings, further research regarding the predictive and prognostic value of the classification schemes is needed. Additional longitudinal studies examining the predictive and prognostic value of the GEHS classification scheme regarding various interventions (duty limitations, splinting, mobilization, injection, and surgical release) is recommended. Future trials should also go beyond subjective reporting and include various outcomes measures (surgical findings, self-report, strength, sensation, serial NCS/EMG findings, physical performance testing, and healthcare utilization) and rigorous statistical analysis to determine the prognostic utility and cost/benefit of this classification scheme.

Summary and Clinical Relevance

The GEHS neurophysiological classification system for patients with neuropathy of the ulnar nerve at the elbow equips healthcare providers with an enhanced system of electrophysiological evaluation and grading scale. As such, it now provides clinical electrophysiologists with a more complete neurophysiological classification system for use when preparing electrophysiological testing reports for patients with this disorder. Availability of expanded electrophysiological data that includes both NCS and EMG testing provides the healthcare team and the patient with more detailed information that may be useful in determining next treatment steps as well as long-term prognosis. Future research comparing the psychometric properties and prognostic utility of the GEHS ncurophysiologic classifications is warranted.

References

(1.) Dumitru D, Amato A A, Zwarts M. Electrodiagnostic Medicine. 2nd ed. Philadelphia, PA: Hanley & Belfus Inc; 2001.

(2.) Kimura J. Electrodiagnosis in Diseases of Nerve and Muscle. 3rd ed. New York, NY: Oxford University Press, Inc; 2001.

(3.) American Association of Electrodiagnostic Medicine, American Academy of Neurology, American Academy of Physical Medicine and Rehabilitation. Practice parameter for electrodiagnostic studies in ulnar neuropathies at the elbow. Muscle Nerve. 1999;22(suppl):S171-S205.

(4.) Posner MA. Compressive ulnar neuropathies at the elbow: I. Etiology and diagnosis. J Am Acad Ortho Surg. 1998;6(5):282-288.

(5.) Landau ME, Campbell WW. Clinical features and electrodiagnosis of ulnar neuropathies. Phys Med Rehab Clin N Am. 2013;24(l):49-66.

(6.) Dawson DM, Hallett M, Millender LIT Entrapment Neuropathies. 2nd ed. Boston, MA: Little, Brown & Co; 1990.

(7.) MacDermid JC, Grewal R. Development and validation of the patient-rated ulnar nerve evaluation. BMC Musculoskeletal Disord. 2013; 14:146. Available at: https://doi.org/10.1186/1471-2474-14-146.

(8.) Eliaspour D, Sedighipour L, Iledayati-Moghaddam MR, et al. The pattern of muscle involvement in ulnar neuropathy at the elbow. Neurol India. 2012;60(l):36-39.

(9.) Mandelli C, Baiguini M. Ulnar nerve entrapment neuropathy at the elbow: decisional algorithm and surgical considerations. Neurocirugia (Astur). 2009;20(l):31-38.

(10.) Burns PB, Kim HM, Gaston RG, et al. Predictors of functional outcomes after simple decompression for ulnar neuropathy at the elbow: a multicenter study by the SUN study group. Areh Phys Med Rehabil. 2014;95(4):680-685.

(11.) Chimenti PC, Hammert WC. Ulnar neuropathy at the elbow: an evidence-based algorithm. Hand Clin. 2013;29(3):435-442.

(12.) Song VV, Waljee JF, Burns PB, et al. An outcome study for ulnar neuropathy at the elbow: a multicenter study by the surgery for ulnar nerve (SUN) study group. Neurosurgery. 2013;72(6):971 -981.

(13.) Moore KL, Dalley AF, Agur AMR. Clinically-Oriented Anatomy. 7th ed. Baltimore, MD: Wolters Kluwer/Lippincott Williams and Wilkins; 2014.

(14.) Netter FH. Netter Atlas of Anatomy. 4th ed. Philadelphia, PA: Elsevier; 2006.

(15.) Greathouse DG. A classification system for patients with ulnar nerve mononeuropathy at the elbow. Electroneuromvographic Symposium Proceedings. Rocky Mountain University of Health Professions; March 27, 2015:50-74.

(16.) Greathouse DG, Root TM, Carrillo CR, et al. Clinical and electrodiagnostic abnormalities of the median nerve in dental assistants. J Orthop Sports Phys Ther. 2009;39(9):693-701.

(17.) Shaffer SW, Moore R, Foo S, Henry N, Moore JH, Greathouse DG. Clinical and electrodiagnostic abnormalities of the median nerve in U.S. Army dental assistants at the onset of training. US Armv Med Dep J. July-September 2012:72-81.

(18.) Shaffer SW, Koreerat NR, Rice L, Santillo DR, Moore JH, Greathouse DG. Median and ulnar neuropathies in U.S. Army Medical Command band members. Med Probi Perform Art. 2013;28(4):188-194.

(19.) Shaffer SW, Alexander K, Huffman D, Kambe C, Miller R, Moore JH, Greathouse DG. Median and ulnar neuropathies in US Army dental personnel at Fort Sam Houston, Texas. US Army Med Dep J. April-June 2014:1-9.

(20.) Dellon AL. Diagnosis and treatment of ulnar nerve compression at the elbow. Tech Hand Up Extrem Surg. 2000:4(2): 127-136.

(21.) McGowan AJ. The results of transposition of the ulnar nerve for traumatic ulnar neuritis. J Bone Joint Surg Br. 1950;32-B(3):293-301. Available at: http://bjj.boneandjoint.org.Uk/content/32-B/3/293. full.pdf. Accessed October 4, 2017.

(22.) Gabei GT, Amadio PL. Reoperation for failed decompression of the ulnar nerve in the region of the elbow. J Bone Joint Surg Am. 1990;72(2):213-219.

(23.) Logigian EL, Villanueva R, Twydell PT, et al. Electrodiagnosis of ulnar neuropathy at the elbow (UNE): a Bayesian approach. Muscle Nerve. 2014;49(3):337-344.

(24.) Friedrich JM, Robinson LR. Prognostic indicators from electrodiagnostic studies for ulnar neuropathy at the elbow. Muscle Nerve. 2011;43(4):596-600.

(25.) Agnew SP, Minieka MM, Patel RM, Nagle DJ. Correlation between preoperative Kimura inching studies and intraoperative findings during endoscopic-assisted decompression of the ulnar nerve at the elbow. Hand (N Y). 2012;7(4):370-373.

David G. Greathouse, PT, PhD

Greg Ernst, PT, PhD

John S. Halle, PT, PhD

COL Scott W. Shaffer, SP, USA

Dr Greathouse is Director, Clinical Electrophysiology Services, Texas Physical Therapy Specialists, New Braunfels, TX, and Adjunct Professor, US Army-Baylor University Doctoral Program in Physical Therapy, Fort Sam Houston, TX.

Dr Ernst is an Associate Professor, Department of Physical Therapy, UT Health Science Center, San Antonio, TX, and Clinical electrophysiologist, Hand Center of San Antonio, San Antonio, TX.

Dr Halle is a Professor, School of Physical Therapy, Belmont University, Nashville, TN, and a Clinical electrophysiologist, Department of Neurology, Blanchfield Army Community Hospital, Ft. Campbell, KY.

COL Shaffer is Dean, Graduate School and Associate Professor, US Army-Baylor University Doctoral Program in Physical Therapy, Fort Sam Houston, TX, Chief, Physical Therapist Section, and Assistant Chief, Army Medical Specialist Corps, Fort Sam Houston, TX.
Table 1. GEHS Neurophysiological Classification System for Patients
with Neuropathy of the Ulnar Nerve at the Elbow. (15)

EARLY MILD (conduction block)

Sensory-->40% decrease in SNAP amplitude; eg, 40 [micro]V SNAP
Amplitude BE-W, 20 [micro]V SNAP amplitude AE-BE, 20 [micro]V SNAP
Amplitude difference (50%) and/or

Motor-->20% decrease in CMAP amplitude AE/BE; eg, 8 mV CMAP
amplitude BE-W, 4 mV CMAP amplitude AE-BE, 4 mV CMAP amplitude
difference (50%).

Normal Findings: Normal motor and sensory NCVs and latencies when
compared to a Table of Normal NCS Values; normal EMG of
ulnar innervated muscles (1st PI, ADM, FDP D4-5 & FCU).

MILD (myelin only)

Sensory--<50 m/sec SNCV AE-BE or >10 m/sec SNCV AE-BE difference
when compared to BE-W, SNCV (AE- BE SNCV >50 m/sec)
>40% decrease in SNAP amplitude AE/BE;

Motor--<50 m/sec MNCV AE-BE or >10 m/sec MNCV AE-BE difference
when compared to BE-W MNCV (AE- BE MNCV >50 m/sec)
>20% decrease in CMAP amplitude AE/BE;
Sensory and Motor--abnormal findings as listed above for both
motor and sensory fibers.

EMG: normal EMG of ulnar innervated muscles (1st PI. ADM, FDP D4-5
& FCU).

Normal NCS Findings: Normal MNCV and SNCV BE-W and distal motor and
sensory latencies and amplitudes when compared to a Table of Normal
NCS Values (Table being used in individual lab).

MODERATE (myelin and axon)

EMG--increased insertional activity and presence of abnormal
spontaneous electrical activity in one of the following muscles:
1st DI, ADM, FDP D4-D5, or FCU; may have decreased interference
pattern on maximum voluntary contraction in one of the ulnar
innervated muscles. *

Conduction Block--normal motor and sensory conduction studies; may
have decreased SNAP and/or CMAP amplitudes at the AE
stimulation site; abnormal EMG findings as presented above.

Sensory--<50 m/sec SNCV AE-BE >40% decrease in SNAP amplitude
AE/BE may have abnormal distal sensory latency and/or amplitude
when compared to a Table of Normal NCS Values.

Motor--<50 m/sec MNCV AE-BE >20% decrease in CMAP amplitude AE/BE *
--may have abnormal distal motor latency and/or amplitude when
compared to a Table of Normal NCS Values.*

Normal Findings: Normal distal motor and sensory latencies and
amplitudes and normal BE-W MNCV and SNCV when compared to a Table
of Normal NCS Values; normal shape, amplitude and duration of MUPs
In ulnar innervated muscles.

SEVERE (myelin and axon)

EMG--increased insertional activity and presence of abnormal
spontaneous electrical activity in two or more of the following
muscles: 1st DI, ADM, FDP D4-D5, or FCU: decreased interference
pattern on maximum voluntary contraction in two or more of the
ulnar innervated muscles* may have increased amplitude (>10 mV)
and/or duration (>15 ms) MUPs in one or more of the ulnar
innervated muscles.

Conduction Block--Normal motor and sensory conduction studies; may
have decreased SNAP and/or CMAP amplitudes at the AE stimulation
site; abnormal EMG findings as presented above.

Sensory--<50 m/sec SNCV abnormal distal sensory latency and/or
amplitude when compared to a Table of Normal NCS Values. *

Motor--<50 m/sec MNCV AE-BE abnormal distal motor latency and/or
Amplitude when compared to a Table of Normal NCS Values. *

Summary of Severe Compared to Moderate:

1. Two or more ulnar innervated muscles with EMG changes.
2. Sensory and motor changes are abnormal, not based on percentage
decreases, but on comparison to Table of Normal NCS Values being
used in individual labs.

* Electrophysiologic evidence of axonal loss neuropathic process.

Glossary

ADM--abductor digiti minimi
AE--above elbow
BE--below elbow
CMAP--compound motor action potential
DML--distal motor latency
D4--digit 4 (ring finger)
D5--digit 5 (little finger)
1st DI--first dorsal interosseous
DSL--distal sensory latency
EMG--electromyography
FCU--flexor carpi ulnaris
FPD D4-D5--flexor digitorum profundus D4 and D5 (ring and little
fingers)
MNCV--motor nerve conduction velocity
MUPs--motor unit potentials
NCS--nerve conduction studies
SNAP--sensory nerve action potential
SNCV--sensory nerve conduction velocity
W--wrist

Table 2. Case 1: Nerve Conduction Study Results. Note: clinically
noteworthy values identified by shaded data cells.

Anti Sensory Summary

 Site     NR   Peak     Norm Peak      P-T Amp     Norm P-T Amp
                (ms)       (ms)       ([micro]V)    ([micro]V)

Left Superficial Radial Anti Sensory (Base 1st Digit)

  D1            2.3        <2.7          15.8           >

Right Superficial Radial Anti Sensory (Base 1st Digit)

  D1            2.0        <2.7          10.8           >

Ortho Sensory Summary

Left Median Ortho Sensory (Wrist)

 Palm           2.1        <2.2         180.5          >15
  D2            3.4        <3.6          49.2          >15

Right Median Ortho Sensory (Wrist)

 Palm           2.2        <2.2         171.7          >15
  D2            3.5        <3.6          28.9          >15

Left Ulnar Ortho Sensory (Wrist)

 Palm           5.6        <2.2          15.1          >10
  D5      NR               <3.5                        >10

Right Ulnar Ortho Sensory (Wrist)

 Palm           2.2        <2.2          10.0          >10
  D5            2.9        <3.5          11.2          >10

Motor Summary

 Site     NR   Onset    Norm Onset     O-P Amp      Norm O-P
                (ms)       (ms)          (mV)        Amp (mV)

Left Median Motor (Abductor Pollicis Brevis)

 Wrist          3.8        <4.2          9.6            >5
 Elbow          9.1                      8.2

Right Median Motor (Abductor Pollicis Brevis)

 Wrist          3.8        <4.2          12.9           >5
 Elbow          9.4                      10.2

Left Ulnar Motor (Abductor Digiti Minimi)

 Wrist          3.5        <3.6          4.3            >5
B Elbow         9.1                      2.1
A Elbow         11.6                     4.5

Right Ulnar Motor (Abductor Digiti Minimi)

 Wrist          3.0        <3.6          7.7            >5
B Elbow         8.1                      6.6
A Elbow         10.2                     6.6

Anti Sensory Summary

 Site     Site 1     Site 2     Delta-P    Dist   Vel     Norm Vel
                                  (ms)     (cm)   (m/s)     (m/s)

Left Superficial Radial Anti Sensory (Base 1st Digit)

  D1        D1      Base 1st      2.3      10.0    43
                    Digit

Right Superficial Radial Anti Sensory (Base 1st Digit)

  D1        D1      Base 1st      2.0      10.0    50
                      Digit

Ortho Sensory Summary

Left Median Ortho Sensory (Wrist)

 Palm      Palm       Wrist       2.1      8.0     38
  D2        D2        Wrist       3.4      14.0    41

Right Median Ortho Sensory (Wrist)

 Palm      Palm       Wrist       2.2      8.0     36
  D2        D2        Wrist       3.5      14.0    40

Left Ulnar Ortho Sensory (Wrist)

 Palm      Palm       Wrist       5.6      8.0     14
  D5        D5        Wrist                14.0

Right Ulnar Ortho Sensory (Wrist)

 Palm      Palm       Wrist       2.2      8.0     36
  D5        D5        Wrist       2.9      14.0    48

Motor Summary

 Site     Site 1     Site 2     Delta-0    Dist   Vel     Norm Vel
                                  (ms)     (cm)   (m/s)     (m/s)

Left Median Motor (Abductor Pollicis Brevis)

 Wrist     Elbow      Wrist       5.3      28.0    53        >50
 Elbow

Right Median Motor (Abductor Pollicis Brevis)

 Wrist     Elbow      Wrist       5.6      31.0    55        >50
 Elbow

Left Ulnar Motor (Abductor Digiti Minimi)

 Wrist    B Elbow     Wrist       5.6      25.5    46        >50
B Elbow   A Elbow    B Elbow      2.5      13.5    54        >50
A Elbow

Right Ulnar Motor (Abductor Digiti Minimi)

 Wrist    B Elbow     Wrist       5.1      26.0    51        >50
B Elbow   A Elbow    B Elbow      2.1      12.0    57        >50
A Elbow

Glossary

Amp--amplitude
A Elbow--above elbow
B Elbow--below elbow
D1--digit 1 (thumb)
D2--digit 2 (index finger)
Dist--distance
Norm--normal
NR--no response
O--onset
P- peak
T--trough
Vel--velocity

Table 3. Case 1: Electromyography Results. Note: clinically
noteworthy values are indicated by shaded cells.

Side *       Muscle             Nerve          Root    Ins Act

 Left      lstDorlnt            Ulnar         C8-T1     Incr
 Left    Abd Poll Brev         Median         C8-T1      Nml
 Left    PronatorTeres         Median          C6-7      Nml
 Left    Flex Poll Long          AIN          C8-T1      Nml
 Left        Biceps          Musculocut        C5-6      Nml
 Left       Triceps            Radial         C6-7-8     Nml
 Left       Deltoid           Axillary         C5-6      Nml
 Left     ABD Dig Min           Ulnar         C8-T1     Incr
 Left     FlexCarpiUIn          Ulnar         C8-T1      Nml
 Left    Ext Poll Long    Radial (Post Int)    C7-8      Nml

Side *   Fibs   Psw   Amp   Dur   Poly    Recrt    Int Pat

 Left     2+    3+    Nml   Nml    0     Reduced     50%
 Left    Nml    Nml   Nml   Nml    0       Nml       Nml
 Left    Nml    Nml   Nml   Nml    0       Nml       Nml
 Left    Nml    Nml   Nml   Nml    0       Nml       Nml
 Left    Nml    Nml   Nml   Nml    0       Nml       Nml
 Left    Nml    Nml   Nml   Nml    0       Nml       Nml
 Left    Nml    Nml   Nml   Nml    0       Nml       Nml
 Left     2+    3+    Nml   Nml    0     Reduced     50%
 Left    Nml    Nml   Nml   Nml    0       Nml       Nml
 Left    Nml    Nml   Nml   Nml    0       Nml       Nml

Side *     Comment

 Left    fib amp <100
 Left
 Left
 Left
 Left
 Left
 Left
 Left    fib amp <100
 Left
 Left

* Electromyographic testing of the right upper extremity was
not performed.

Glossary

Amp--amplitude
Dur--duration
Fibs--fibrillation potentials
Incr--increased
Ins Act--insertional activity
Int Pat--interference pattern
Nml--normal
Poly--polyphasics
Recrt--recruitment

Table 4. Case 2: Nerve Conduction Study Results. Note:
clinically noteworthy values identified by shaded data cells.

Anti Sensory Summary

 Site       NR      Peak (ms)   Norm Peak     P-T Amp
                                   (ms)      ([micro]V)

Left Superficial Radial Anti Sensory (Base 1st Digit)

  D1                   2.6         <2.7         23.9

Right Superficial Radial Anti Sensory (Base 1st Digit)

  D1                   2.6         <2.7         20.6

Ortho Sensory Summary

Left Median Ortho Sensory (Wrist)

 Palm                  2.0         <2.2        112.5
  D2                   3.3         <3.6         20.0

Right Median Ortho Sensory (Wrist)

 Palm                  2.1         <2.2         33.8
  D2                   3.5         <3.6         22.6

Left Ulnar Ortho Sensory (Wrist)

 Palm                  2.2         <2.2         15.3
  D5                   3.5         <3.5         13.3

Right Ulnar Ortho Sensory (Wrist)

 Palm                  2.3         <2.2         16.7
  D5                   3.5         <3.5         12.4

Motor Summary

 Site       NR       Onset      Norm Onset    O-P Amp
                      (ms)         (ms)         (mV)

Left Median Motor (Abductor Pollicis Brevis)

 Wrist                 4.0         <4.2         9.0
 Elbow                 9.4                      9.0

Right Median Motor (Abductor Pollicis Brevis)

 Wrist                 4.1         <4.2         10.0
 Elbow                10.5                      9.4

Left Ulnar Motor (Abductor Digiti Minimi)

 Wrist                 3.5         <3.6         6.5
B Elbow                8.2                      6.7
A Elbow               10.2                      6.7

Right Ulnar Motor (Abductor Digiti Minimi)

 Wrist                 3.8         <3.6         7.5
B Elbow                8.5                      7.2
A Elbow               11.4                      6.4
Axilla                13.3                      7.0

Anti Sensory Summary

 Site     Norm P-T Amp    Site 1        Site 2        Delta-P (ms)
           ([micro]V)

Left Superficial Radial Anti Sensory (Base 1st Digit)

  D1            >           Dl      Base 1st Digit         2.6

Right Superficial Radial Anti Sensory (Base 1st Digit)

  D1            >           Dl      Base 1st Digit         2.7

Ortho Sensory Summary

Left Median Ortho Sensory (Wrist)

 Palm          >15         Palm         Wrist              2.0
  D2           >15          D2          Wrist              3.3

Right Median Ortho Sensory (Wrist)

 Palm          >15         Palm         Wrist              2.1
  D2           >15          D2          Wrist              3.5

Left Ulnar Ortho Sensory (Wrist)

 Palm          >10         Palm         Wrist              2.2
  D5           >10          D5          Wrist              3.5

Right Ulnar Ortho Sensory (Wrist)

 Palm          >10         Palm         Wrist              2.3
  D5           >10          D5          Wrist              3.5

Motor Summary

 Site     Norm O-P Amp    Site 1        Site 2        Delta-0 (ms)

Left Median Motor (Abductor Pollicis Brevis)

 Wrist         >5          Elbow        Wrist              5.4
 Elbow

Right Median Motor (Abductor Pollicis Brevis)

 Wrist         >5          Elbow        Wrist              6.4
 Elbow

Left Ulnar Motor (Abductor Digiti Minimi)

 Wrist         >5         B Elbow       Wrist              4.7
B Elbow                   A Elbow      B Elbow             2.0
A Elbow

Right Ulnar Motor (Abductor Digiti Minimi)

 Wrist         >5         B Elbow       Wrist              4.7
B Elbow                   A Elbow      B Elbow             2.9
A Elbow                   Axilla       A Elbow             1.9
Axilla

Anti Sensory Summary

 Site     Dist    Vel     Norm Vel
          (cm)    (m/s)     (m/s)

Left Superficial Radial Anti Sensory (Base 1st Digit)

  D1      10.0     38

Right Superficial Radial Anti Sensory (Base 1st Digit)

  D1      10.0     37

Ortho Sensory Summary

Left Median Ortho Sensory (Wrist)

 Palm      8.0     40
  D2      14.0     42

Right Median Ortho Sensory (Wrist)

 Palm      8.0     38
  D2      14.0     40

Left Ulnar Ortho Sensory (Wrist)

 Palm      8.0     36
  D5      14.0     40

Right Ulnar Ortho Sensory (Wrist)

 Palm      8.0     35
  D5      14.0     40

Motor Summary

 Site     Dist    Vel     Norm Vel
          (cm)    (m/s)     (m/s)

Left Median Motor (Abductor Pollicis Brevis)

 Wrist    29.0 1 54          >50
 Elbow

Right Median Motor (Abductor Pollicis Brevis)

 Wrist    33.0     52        >50
 Elbow

Left Ulnar Motor (Abductor Digiti Minimi)

 Wrist    25.0     53        >50
B Elbow   13.0     65        >50
A Elbow

Right Ulnar Motor (Abductor Digiti Minimi)

 Wrist    25.0     53        >50
B Elbow   13.0     45        >50
A Elbow   14.0     74
Axilla

Glossary
Amp--amplitude
A Elbow--above elbow
B Elbow--below elbow
D1--digit 1 (thumb)
D2--digit 2 (Index finger)
Dist--distance
Norm--normal
NR--no response
O--onset
P--peak
T--trough
Vel--velocity

Table 5. Case 2: Electromyography Results. Note: clinically
noteworthy values are indicated by shaded cells.

Side *      Muscle         Nerve       Root    Ins Act   Fibs   Psw

Right      1stDorInt       Ulnar      C8-T1     Incr      1+    2+
Right    Abd Poll Brev     Median     C8-T1      Nml     Nml    Nml
Right    PronatorTeres     Median      C6-7      Nml     Nml    Nml
Right    Ext Poll Long      PIN         C8       Nml     Nml    Nml
Right       Biceps       Musculocut    C5-6      Nml     Nml    Nml
Right       Triceps        Radial     C6-7-8     Nml     Nml    Nml
Right       Deltoid       Axillary     C5-6      Nml     Nml    Nml
Right     ABD Dig Min      Ulnar      C8-T1     Incr      2+    2+
Right    FlexCarpiUIn      Ulnar      C8-T1     Incr      1+    1+

Side *   Amp   Dur   Poly    Recrt    Int Pat      Comment

Right    Nml   Nml    0       Nml       Nml     fib amp <100>
Right    Nml   Nml    0       Nml       Nml
Right    Nml   Nml    0       Nml       Nml
Right    Nml   Nml    0       Nml       Nml
Right    Nml   Nml    0       Nml       Nml
Right    Nml   Nml    0       Nml       Nml
Right    Nml   Nml    0       Nml       Nml
Right    Nml   Nml    0     Reduced     75%     fib amp <100>
Right    Nml   Nml    0     Reduced     75%     fib amp <100>

* Electromyographic testing of the left upper extremity was not
performed.

Glossary

Amp--amplitude
Dur--duration
Fibs--fibrillation potentials
Incr--increased
Ins Act--insertional activity
Int Pat--interference pattern
Nml--normal
Poly--polyphasics
Recrt--recruitment
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Author:Greathouse, David G.; Ernst, Greg; Halle, John S.; Shaffer, Scott W.
Publication:U.S. Army Medical Department Journal
Article Type:Report
Date:Oct 1, 2017
Words:7062
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