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Piriformis Syndrome " a rare cause of extraspinal sciatica.

Byline: Shumaila Arooj and Muhammad Azeemuddin

AbstractPiriformis syndrome is a rare entity resulting in severe unilateral isolated buttock pain shooting in nature non discogenic in origin. MR imaging of pelvis plays an important role in such patients to see the normal anatomy of piriformis muscle and its relationship with sciatic nerve. A 35-year-old woman presented with one year history of radiating leg pain with normal MR lumbosacral spine. MRI pelvis showed an abnormal orientation of left sciatic nerve through cleaved fibers of the piriformis muscle. The patient's symptoms were relieved by surgical decompression. The purpose of this case report is to show the role and importance of MR imaging for tracing sciatic nerve and its relationship to the Piriformis muscle. MR imaging of pelvis for sciatic nerve plays an important role in symptomatic patients with isolated buttock pain having normal MRI lumbosacral spine.

Keywords: Piriformis muscle syndrome Sciatic nerve MRI.

IntroductionPiriformis syndrome is a rare syndrome which causes severe low back pain most likely due to trapped sciatic nerve in the greater sciatic notch. It is usually caused either by the hypertrophy or inflammation of piriformis muscle or anatomical variation and relationship of sciatic nerve to muscle fibres of piriformis.1 Piriformis syndrome was first described by Yeoman in 1928.2 The knowledge regarding this syndrome is important especially as a radiologist as being unaware of this entity leads to delayed or misdiagnosis. The patient at times is referred for psychiatrist consult due to mismatch of symptoms and spinal MR findings.

A case of Piriformis syndrome is presented in the neurology clinic with similar complaints secondary to abnormal course of sciatic nerve through cleaved fibres of piriformis muscle. It was revealed on MRI of pelvis and later confirmed at surgery.

Case ReportA 35-year-old woman presented in the neurology clinic in April 2012 at Aga Khan University Hospital Karachi with severe disabling lower backache. According to the patient the pain was severe and radiating to left lower limb. It was related to movement and increased by prolonged sitting and walking. There was no focal neurological deficit or urinary or faecal incontinence. MR lumbosacral spine examination was performed on 1.5 T Avanto 76x18 Siemens scanner with spine coil. Mild disc bulges were found at L4-L5 and L5-S1 levels without any neural foraminal encroachment. Representative MR images of the lumbar spine are shown in Figures-1a and 1b respectively. The patient was given analgesics and was advised to have physiotherapy. The patient again presented in March 2013 after an interval of almost one year. Her repeat MR lumbosacral spine did not show any significant interval change as shown in Figure-1(c) and (d).

Meanwhile she was also referred to psychiatrist as her symptoms did not match her MR picture. The patient was then referred again an MRI of pelvis in April 2013 with attention focused on the sacral plexus and piriformis muscle to narrow the possibilities. Dedicated thin T2 weighted axial cuts through pelvis focused on the sciatic nerve were taken. This showed an abnormal orientation of sciatic nerve through cleaved/split fibers of the left piriformis muscle with normal signal intensity of sciatic nerve on T1- and T2-weighted sequences and normal surrounding structures (Figures-2a b c and d respectively).

The patient underwent left sciatic nerve decompression. The nerve was identified and path traced proximal to sciatic notch. Piriformis muscle was split to relieve sciatic compression. The postoperative course was uneventful. The patient reported complete relief of symptoms immediately and later five months after the operation.

DiscussionThe Piriformis Muscle originates from the pelvic surface of the sacral segments S2-S4 the adjacent sacro-iliac joint the anterior sacro-spinous ligament and the sacro- tuberous ligament. It courses through the greater sciatic notch to insert onto the greater trochanter of the femur. The sciatic nerve exits the pelvis below the belly of the muscle. Many congenital variations exist; the nerve may divide proximally the nerve or a division of the nerve may pass through the belly of the muscle through its tendons or between the part of a congenitally bifid muscle.3 The Piriformis Syndrome was first reported some 70 years back3 in literature as a rare yet disputed cause of sciatic nerve entrapment.4 It is due to an abnormality of Piriformis muscle such as its hypertrophy inflammation or anatomical variation. This results in impingement of sciatic nerve.5 It is an important cause of radiating leg pain found to be present in 6% sciatica cases seen in general practice.6 The purpose of this case report is to show the importance of MR pelvis imaging for tracing normal anatomy of Sciatic nerve and its relationship to the Piriformis muscle especially in symptomatic patients.

In patients with Piriformis Syndrome MR scanning of pelvis provides anatomical details in a sophisticated way revealing muscle abnormalities and the relationship of nerve course to muscle fibres as well as greater sciatic notch. Piriformis syndrome is characterized by shooting/radiating pain with numbness and tingling in unilateral hip thigh and distribution of sciatic nerve.7 These symptoms can be elicited on physical examination by digital pressure over this muscle on lateral pelvic wall. Initially the diagnosis was made only on the basis of clinical picture and imaging was ignored. Now it is an established fact that MRI is a valuable noninvasive mode of imaging not only revealing the piriformis muscle anatomy but also its relationship to sciatic nerve.48 MRI can detect oedema of the nerve fibres and can rule out other possible etiologies like disc herniation spinal canal stenosis bony lesions or mass lesions.8 According to a systemic review published in Eur Spine J. 20103 79 case studies with individual data reported congenital and acquired anomalies of the Piriformis Muscle with and without sciatic nerve impingement.3 Jankiewicz et al reported 1 patient with an enlarged piriformis muscle with normal signal intensity. Unlike other patients described by Jankiewicz et al8 and Rossi et al4 the reported patient had a piriformis muscle of normal size but with split and cleaved fibres through which the nerve was coursing through and thus had movement associated buttock pain. The sciatic nerve had normal size and signal characteristics. The discogenic causes of radiating leg pain were confidently excluded on repeated MR LS spine over one year which confirmed no significant disease progression.

Different treatment options comprise of nonsteroidal anti-inflammatory agents and corticosteroids. Few patients benefit from injectable local anaesthetics. Physiotherapy does play a role. This patient could not be managed conservatively. For patients with symptoms refractory to these conservative treatments surgical release of the piriformis muscle is often recommended and has been reported to be effective in relieving the symptoms.910 The patient underwent left sciatic nerve decompression. The nerve was identified and path traced proximally to sciatic notch. Piriformis muscle was split to relieve sciatic compression. The patient's symptoms dramatically improved. The surgical decompression outcome in our patient was excellent.

Piriformis syndrome is a clearly recognized unique disease exclusively different from the typical pattern of discogenic causes of sciatica. The sooner it is detected the better is the outcome and the more effective is the treatment.

ConclusionThe diagnosis of Piriformis syndrome can be missed or delayed in the absence of typical clinical symptoms or absence of definite diagnostic tests. MRI can be used to make a correct diagnosis to specify anatomic relationships for preoperative planning and to differentiate piriformis syndrome from the more common causes of lower back pain and sciatica. Therefore familiarity with the appearance of piriformis syndrome on MRI is important to facilitate appropriate diagnosis and treatment.

References1. Ozaki S Hamabe T Muro T. Piriformis syndrome resulting from an anomalous relationship between the sciatic nerve and piriformis muscle. Orthopedics 1999; 22:771 -2.2. Yeoman W. The relation of arthritis of the sacroiliac joint to sciatica: with an analysis of 100 cases. Lancet 1928; 2:1119 -223. Hopayian K Song F Riera R Sambandan S. The clinical features of the piriformis syndrome: a systematic review Eur Spine J 2010; 19: 2095-09.

4. Rossi P Cardinali P Serrao M Parisi L Bianco F De Bac S. Magnetic resonance imaging findings in piriformis syndrome: A case report. Arch Phys Med Rehabil 2001; 82: 519-21.5. Silver JK Leadbetter WB. Piriformis syndrome: assessment of current practice and literature review. Or thopedics 1998;21:1133-5

6. Parziale JR Hudgins TH Fishman LM. The piriformis syndrome. Am J Orthop 1996; 25: 819-237. Rodrigue T Hardy RW. Diagnosis and treatment of piriformis syndrome. Neurosurg Clin N Am 2001; 12: 311 -9.

8. Jankiewicz JJ Hennrikus WL Houkom JA. The appearance of the piriformis muscle syndrome in computed tomography and magnetic resonance imaging: a case report and review of the literature. Clin Orthop 1991; 262: 205 -99. Sayson SC Ducey JP Maybrey JB Wesley RL Vermilion D. Sciatic entrapment neuropathy associated with an anomalous piriformis muscle. Pain 1994; 59:149-52.10. Beauchesne RP Schutzer SF. Myositis ossificans of the piriformis muscle: an unusual cause of piriformis syndrome-a case report. J Bone Joint Surg Am 1997; 79:906 -10.

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Treatment of tar burns: two case reports

By: Sevdegul Karadas Hayriye GAlnA1/4llA1/4 Mehmet Resit OncA1/4 Hatice Kara and HA1/4seyin Baltacioglu

_: AbstractHot tar burns are still a challenging clinical form because the removal of tar is very difficult for the emergency physician and there is no specified appropriate agent for the removal of tar. In this study two patients with hot tar burns who were treated with diesel sunflower oil and mayonnaise are presented.

Keywords: Tar Sunflower oil Mayonnaise.

IntroductionTar is a commonly used material especially in areas such as surfacing roads tiling roofs and waterproofing cars.1Tar can be obtained using dry distillation from coal stones and various kinds of wood.2 The boiling point of paving tar is 140C thus skin burns from tar may be severe and deep.13

From various studies it is reported that occupational burns account for 10-45% of all burn events.45 Tar burns constitute 60.3% of all chemical burns6 whereas of all burn cases only a small proportion are from hot tar.1

Tar burns usually are occupational in nature and are observed mostly in male patients.6 In the treatment of hot tar burns it is important to restrict tissue damage and prevent the further spread of the tar.7 However in the emergency department (ED) it may be difficult to remove tar without additional tissue loss due to the dense structure and high temperature of the tar. In the literature many substances like sunflower oil and butter have been mentioned being used to remove tar from the affected area.1 Here two cases of a hot tar burn treated with diesel sunflower oil and mayonnaise are presented.

Case ReportCase 1: In August 2013 a 23-year-old man paving worker was injured by hot tar which fell from a truck splashing his arms and anterior chest wall. He was admitted to the ED 30 minutes after the event. Before he arrived at ED he had applied cold water to the area affected by the tar. On admission to ED his vital signs were normal. His physical examination showed that his upper extremity and anterior chest wall were covered with tar (Figure-1A). In ED initially diesel was used for reducing thick tar layer. Then sunflower oil was utilized to remove the remaining tar. First-second degree burns were shown in his upper extremity (Figure-1B). He was then treated for second- degree burns for 2 weeks.

Case 2: In October 2013 a 45-year-old man worker had hot tar splashed on his face from a truck. He was admitted to our ED 20 minutes after the event. On admission his vital signs were normal. A small area of his face was covered with tar (Figure-2A). In ED his face was successfully cleaned with mayonnaise (Figure-2B).

DiscussionHot tar burns are still a challenging clinical form of thermal injury since the removal of tar is very difficult for the emergency physician and it is still not clear which are the appropriate agents for the removal of tar.1

In a 2008 study related to chemical burns conducted in Iran Maghsoudi et al stated that chemical burns accounting for 2.4% of the total admissions and of these tar burns ratio was 60.3%. Tar burns were found to be common among paving workers in this study.6 In the same study the male to female ratio was 10 to 1 and the mean age was 35.3.6 In both the presented cases victims were male paving workers at 23 and 45 years of age.

In another study it was reported that hot tar injuries constituted 1.4% of all admissions to Grady Memorial Hospital Burns Unit in Atlanta and 41% of the cases needed surgical management.8 Stratta et al3 stated that early excision and grafting may be required in some cases. Hot tar burns are generally localized on the hands and upper limbs.8 In this study the two cases involved the hand upper limb and face and the hot tar was removed by using non-surgical procedures.

The mechanisms of injury caused by tar include cauldron explosion falling from a height trucks rolling over spillage from buckets and industrial accidents.3 In the presented cases exposure to tar was falling from a truck.

The debridement of tar from the affected tissue without support substances is painful and relatively ineffective.1 In the literature butter sunflower oil and baby oil have been recommended for the removal of hot tar.67 In addition other agents such as alcohol acetone kerosene ether gasoline and aldehydes have been used but these may produce systemic toxicity through absorption.17 A study conducted in Turkey by TA1/4regun et al1 reported four cases of tar burns where the tar was removed by using sunflower oil soaked gauzes on the affected parts. Tar is sterile because of the high temperature but the skin is not1 hence colonization of the wound from the surrounding injured skin may occur. First diesel was used because sunflower oil did not clear all the tar in case 1. Later usage of sunflower oil soaked gauzes on the affected parts was started where the tar was removed painlessly in 20 minutes. In the second case tar was removed easily by using mayonnaise. No surgical intervention was needed for our patients.

ConclusionThus the use of sunflower oil and mayonnaise for removing tar is recommended more over. If sunflower oil and mayonnaise are insufficient for removing a thick layer of tar then the use of diesel is suggested.

References1. TA1/4regA1/4n M OztA1/4rk S Selmanpakoglu N. Sunfloweroil in thetreatment of hot tar burns. Burns 1997; 23: 442-5.2. Paghdal KV Schwartz RA. Topical tar: backtothefuture. J Am Acad Dermatol 2009; 61: 294-302.

3. Stratta R J Saffle JR Kravitz M Warden GD. Management of tar andasphaltinjuries. Am J Surg 1983; 146: 766-9.4. Rossignol AM Locke JA Boyle CM Burke JF. Epidemiology of work-related burn injuries in Massachusetts requiring hospitalization. J Trauma 1986; 26: 1097-101

5. Smith GS Wellman HM Sorock GS Warner M Courtney TK Pransky GS et al. Injuries at work in the US adultpopulation: Contributions to the total injury burden. Am J Public Health 2005;95: 1213-9.6. Maghsoudi H Gabraely N. Epidemiology and outcome of 121 cases of chemicalburn in East Azarbaijanprovince Iran. Injury 2008; 39: 1042-6.

7. Juma A. Bitumenburnsandtheuse of babyoil. Burns 1994; 20: 363-4.8. Renz BM Sherman R. Hot tar burns: 27 hospitalizedcases. J Burn Care Rehabil 1994; 15: 341-5.
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Publication:Journal of Pakistan Medical Association
Date:Aug 31, 2014
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