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Unilateral macroglossia as sole presenting manifestation of internal carotid artery dissection.

Introduction

Painless macroglossia may be caused by amyloidosis (primary or secondary), hypothyroidism, lymphangioma, lipomatosis, reticulum-cell sarcoma, and non-Hodgkin lymphoma. (1) Hypoglossal neuropathy paralyzes both extrinsic and intrinsic muscles of the tongue, and may result from many pathologic processes such as primary skull base neoplasms (e.g., paragangliomas), bony skull base metastases (e.g., from prostate cancer), traumatic skull base fractures, high cervical lymphadenopathy (e.g., tuberculosis), (2) and internal carotid artery (ICA) dissection. (3-5)

Cervical ICA dissection typically presents with ipsilateral laterocervical or facial pain, or Horner syndrome with or without cerebral hemisphere stroke. (6,7) However, 3 to 12% of patients may present with isolated or multiple lower cranial neuropathies. (8,9) As many as 95% of patients with ICA dissection complain of pain at onset, and pain is sometimes the only clinical manifestation (7,10); 0.5% of patients suffer no pain. (8,9)

To the best of the author's knowledge, this is the first report of a painless, unilateral enlargement of the tongue caused by acute hypoglossal nerve denervation as the sole presenting feature of a painless, spontaneous dissection of the distal cervical ICA at the skull base.

Case report

A 56-year-old man presented with an overnight-onset, painless enlargement of the left side of the tongue (figure 1). He complained of slurred speech and occasionally bit his tongue because of the swelling and perceived impaired control. He was initially unsuccessfully treated for angioedema with a 2-week course of oral corticosteroids. A subsequent indirect laryngoscopy-guided biopsy of an apparent submucosal infiltrative mass of the left side of the base of the tongue showed normal tissue. About 6 weeks after the onset of symptoms, a neurologic cranial nerve evaluation revealed subtle asymmetry of the soft palate arches with early atrophy and slight weakness of the left half of the tongue.

Dedicated high-resolution magnetic resonance imaging (MRI) was performed according to an oral cavity-neck protocol with extension to the skull base, utilizing axial and coronal, fat-saturated, T2-weighted, coronal Tl-weighted; and post-gadolinium, axial and coronal, fat-saturated, Tl-weighted sequences. MRI showed (1) prominence of the left side of the tongue base in the oropharynx, best appreciated on T1-weighted images; (2) asymmetric T2 hyperintensity; (3) mild, diffuse enhancement of the left half of the tongue; and (4) atrophy of the left levator veli palatini and tensor veli palatine muscles. The distal cervical portion of the left ICA directly below the skull base contained a luminal, semilunar, peripheral T1- and T2-hyperintense signal abnormality compatible with a subacute mural thrombus, with an intimal flap indicative of a carotid dissection that measured 2.5 cm in length. Mild pseudoaneurysmal enlargement of the left ICA was noted; the vessel lumen was not compromised (figure 2).

[FIGURE 1 OMITTED]

Subsequent brain images showed no evidence of an ischemic complication in the left ICA distribution. These radiographic findings were all compatible with subacute neurogenic denervation of the left half of the tongue from a hypoglossal nerve injury due to ICA dissection.

Treatment was started with an antiplatelet regimen. The patient reported full recovery of tongue bulk and function during a telephone interview 1 year after presentation.

[FIGURE 2 OMITTED]

Discussion

To the best of the author's knowledge, this is the first report of a painless, unilateral peudomass of the tongue as the sole presenting clinical feature of a spontaneous arterial dissection at the skull base. The neurogenic nature of this unilateral tongue enlargement was initially not appreciated, as the hypoglossal nerve injury was not associated with noticeable weakness or atrophy of the tongue muscles. Furthermore, the underlying arterial dissection was spontaneous and painless and without evidence of cerebral ischemia. Nonrecognition of this phenomenon initially led to inappropriate treatment and a nondiagnostic, minor invasive procedure.

Unilateral hypoglossal neuropathy is clinically recognized by deviation of the protruded tongue toward the side of weakness. Additionally, when lying in the floor of the mouth, the tongue may seem enlarged and higher on the weakened side. In this patient, acute hypoglossal neuropathy caused unilateral tongue enlargement without paralysis, and it was mistaken as an infiltrative tongue lesion. Presumably, the acute and incomplete denervation did not cause tongue weakness; atrophy may take a few weeks to manifest. The pathophysiology of this partial hypoglossal nerve injury due to ICA dissection likely rested on compression by mild pseudoaneurysmal vessel dilatation. Alternatively, the expanding ICA-wall hematoma compressed the branches of the ascending pharyngeal artery, thereby interrupting the blood supply via vasa nervorum of the hypoglossal nerve. (11)

Two pathogenetic mechanisms have been proposed to explain the painless nature of the ICA dissection. First, visceral nociceptor adaptation occurs if a dissection develops slowly. (12) Unlike traumatic dissections, spontaneous dissections can sometimes develop gradually and therefore cause no pain. (13,14) A second likely explanation involves structural anomalies in the vessel wall that increase distensibility, thus reducing nociceptor stimulation. (15)

In this patients the MRI soft-tissue study of the oropharynx and neck showed increased signal intensity on T2-weighted images on the left half of the tongue, compatible with acute or subacute denervation. (16,17) Denervation was associated with diffuse unilateral enhancement with gadolinium, which could create the false impression of an infiltrative tongue lesion. However, closer inspection of the imaging studies showed presumed neurogenic atrophy of the left-sided soft-palate muscles, implicating additional partial nerve injuries to the ipsilateral pharyngeal branch of the left vagus nerve and the otitic branch of the mandibular division of the left trigeminal nerve. Furthermore, cephalic extension of the imaging study protocol to include the skull base permitted the detection of an intramural ICA clot and intimal flap compatible with the causative, presumably spontaneous, distal cervical ICA dissection.

Knowledge of the relevant anatomy is vital to understanding the MRI patterns of muscle denervation caused by various cranial neuropathies. Furthermore, the signal changes seen in denervated muscle depend on the time course of the underlying pathology. (18,19)

Acute and subacute denervation results in prolonged T2 relaxation time, producing increased signal in muscle on STIR (short tau inversion recovery) and T2 fat-saturated images. This signal change starts within 48 hours of denervation of muscle and increases with intensity over time. Signal change is thought to result from an enlargement of the capillary bed in the muscle or shift of fluid to the extracellular space. This increased fluid signal in muscle may also be seen in other pathologic processes such as injury, infection, or inflammation. Chronic denervation of the tongue is characterized by fatty atrophy of muscle with increased fat content between muscle fascicles. (20) This results in increased muscle signal on Tl-weighted images with decreased overall muscle bulk.

In conclusion, this report draws attention to the phenomenon of painless, unilateral enlargement of the tongue as the sole clinical presentation of an acute hypoglossal neuropathy due to a spontaneous cervical ICA dissection at the skull base. Appropriate imaging sequences with attention to anatomic detail and altered signal characteristics of structures may help avoid inappropriate treatment and more-or-less invasive diagnostic procedures.

References

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(2.) Tommasi-Davenas C, Vighetto A, Confavreux C, Aimard G. Causes of paralysis of the hypoglossal nerve. Apropos of 32 cases [in French]. Presse Med 1990;19(18):864-8.

(3.) Caranci G, Giacomelli E, Inghilleri M. Unilateral lower cranial nerve palsies as the sole manifestation of internal carotid artery dissection: Case report. Muscle Nerve 2008; Ju118 [Epub ahead of print].

(4.) Lieschke GJ, Davis S, Tress BM, Ebeling P. Spontaneous internal carotid artery dissection presenting as hypoglossal nerve palsy. Stroke 1988;19(9):1151-5.

(5.) Vighetto A, Lisovoski F, Revol A, et al. Internal carotid artery dissection and ipsilateral hypoglossal nerve palsy. J Neurol Neurosurg Psychiatry 1990;53(6):530-1.

(6.) Desfontaines P, Despland PA. Dissection of the internal carotid artery: Aetiology, symptomatology, clinical and neurosonological follow-up, and treatment of 60 consecutive cases. Acta Neurol Belg 1995;95(4):226-34.

(7.) Dziewas R, Konrad C, Drager B, et al. Cervical artery dissection-clinical features, risk factors, therapy and outcome in 126 patients. J Neurol 2003;250(10):1179-84.

(8.) Mokri B, Silbert PL, Schievink WI, Piepgras DG. Cranial nerve palsy in sponateous dissection of the extracranial internal carotid artery. Neurology 1996;46(2):356-9.

(9.) Sturzenegger M. Spontaneous internal carotid artery dissection: Early diagnosis and management in 44 patients. J Neurol 1995;242 (4):231-8.

(10.) Biousse V, Woimant F, Amarenco P, et al. Pain as the only manifestation of internal carotid artery dissection. Cephalalgia 1992;12(5): 314-17.

(11.) Guy N, Deffond J, Gabrillargues J, et al. Spontaneous internalcarotid artery dissection with lower cranial nerve palsy. Can J Neurol Sci 2001;28(3):265-9.

(12.) Cervero F, Laird JM. Visceral pain. Lancet 1999;353(9170): 2145-8.

(13.) Biousse V, D'Anglejan-Chatillon J, Massiou H, Bousser MG. Head pain in non-traumatic carotid artery dissection: A series of 65 patients. Cephalalgia 1994;14(1):33-6.

(14.) Silbert PL, Mokri B, Schievink WI. Headache and neck pain in spontaneous internal carotid and vertebral artery dissections. Neurology 1995;45(8):1517-22.

(15.) Lucas C, Lecroart JL, Gautier C, et al. Impairment of endothelial function in patients with spontaneous cervical artery dissection: Evidence for a general arterial wall disease. Cerebrovasc Dis 2004; 17(2-3):170-4.

(16.) Batchelor TT, Krol GS, DeAngelis LM. Neuroimaging abnormalities with hypoglossal nerve palsies. J Neuroimaging 1997;7(2):86-8.

(17.) Shabas D, Gerard G, Rossi D. Magnetic resonance imaging examination of denervated muscle. Comput Radiol 1987;11(1):9-13.

(18.) Bendszus M, Koltzenburg M, Wessig C, Solymosi L. Sequential MR imaging of denervated muscle: Experimental study. Am J Neuroradiol 2002;23(8): 1427-31.

(19.) Lisle DA, Johnstone SA. Usefulness of muscle denervation as an MRI sign of peripheral nerve pathology. Australas Radiol 2007;51(6): 516-26.

(20.) Cha CH, Patten BM. Amyotrophic lateral sclerosis: Abnormalities of the tongue on magnetic resonance imaging. Ann Neurol 1989;25(5):468-72.

Joerg-Patrick Stubgen, MD

From the Department of Neurology and Neuroscience, Weill Cornell Medical College, New York, N.Y.

Corresponding author: Dr. Joerg-Patrick Stubgen, Weill Cornell Medical College/New York Presbyterian Hospital, 525 E. 68th St., New York, NY 10065-4897. Email: pstuebge@med.cornell.edu
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Title Annotation:ORIGINAL ARTICLE
Author:Stubgen, Joerg-Patrick
Publication:Ear, Nose and Throat Journal
Article Type:Case study
Date:Sep 1, 2011
Words:1680
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