Isolated Horner Syndrome From an Elongated Styloid Process (Eagle Syndrome)

Cerebellar ataxia is an uncommon manifestation of hypothyroidism with unknown pathomechanism. The few descriptions of the clinical phenotype range from limb, gait, and trunk ataxia to various ocular motor abnormalities. We evaluated a 62-year-old woman with previously undetected severe hypothyroidism who presented with prominent saccadic intrusions and gait ataxia. She had high titers of antithyroid autoantibodies and anti-glutamic acid decarboxylase (anti-GAD) antibodies. Horizontal eye movement recordings revealed a series of nearly continuous pseudoharmonic square wave jerks (SWJs) constituting a square wave oscillation. Amplitudes reached maximum values of about 4, and wave frequency approached 100 cycles per minute. Thyroxine substitution and corticosteroid administration had little effect on SWJ parameters. The square wave oscillation nearly completely resolved after a single treatment session with intravenous immunoglobulin suggesting a causal link between an autoimmune process and the cerebellar dysfunction. Current concepts of the genesis of saccadic intrusions favor a role for anti-GAD antibodies in the etiology of SWJs.

Clinical Observation Isolated Horner Syndrome From an Elongated Styloid Process (Eagle Syndrome) Caitlin A. Chang, BSc, Tony Lin, MD, Kevin Fung, MD, Manas Sharma, MD, J. Alexander Fraser, MD Abstract: Eagle syndrome occurs when an elongated styloid process causes otolaryngological or neurological symptoms or signs. We report a patient who had an isolated asymptomatic Horner syndrome that resulted from a pinned internal carotid artery being dynamically injured by an elongated styloid process during chiropractic neck manipulation. There was no evidence of arterial dissection. Journal of Neuro-Ophthalmology 2015;35:387-389 doi: 10.1097/WNO.0000000000000260 © 2015 by North American Neuro-Ophthalmology Society E agle syndrome, while familiar to otolaryngologists, is not commonly encountered by ophthalmologists or neurologists. We describe a case of Eagle syndrome causing an ipsilateral Horner syndrome in the setting of chiropractic neck manipulations. CASE REPORT A 66-year-old woman was referred to neuro-ophthalmology after her optometrist noticed a new asymptomatic right Horner syndrome during a routine yearly eye examination. History included quick thrusting chiropractic neck manipulations 4 months before, hypertension, and dyslipidemia. She was an exsmoker. Thorough questioning revealed no other history of head or neck trauma. Detailed neuro-ophthalmic examination revealed an isolated right Horner syndrome, confirmed with 0.5% apraclonidine and 4% cocaine eyedrop tests. Results of Departments of Ophthalmology (CAC, TL, JAF), Otolaryngology- Head and Neck Surgery (KF), Medical Imaging (MS), and Clinical Neurological Sciences (JAF), Schulich School of Medicine and Dentistry, Western University, London, Ontario, Canada. The authors report no conflicts of interest. Address correspondence to J. Alexander Fraser, MD, Room B7104, London Health Sciences Centre, University Hospital, 339 Windermere Road, London, ON N6A 5A5, Canada; E-mail: [e-mail] Chang et al: J Neuro-Ophthalmol 2015; 35: 387-389 testing with 1% hydroxyamphetamine drops were consistent with a postganglionic (third-order neuron) Horner syndrome. There were no other significant ophthalmic or neurological findings. The patient was prescribed aspirin, 81 mg/d. Chest radiography showed normal lung apices. To rule out arterial dissection related to her chiropractic history, magnetic resonance imaging (MRI) was done and revealed a minor focal caliber change in the right internal carotid artery (ICA) at the level of the C1 vertebra, without associated arterial dissection (Fig. 1). Computed tomographic angiography (CTA) demonstrated abnormal elongation of the styloid processes (36 mm on right, 30 mm on left; normal ,30 mm) (Fig. 2A). The right styloid process pinned the right ICA against the transverse process of the C1 vertebra (Fig. 2B, C), consistent with the "stylocarotid" subtype of Eagle syndrome. The deformed vessel lumen was still widely patent. Further investigation with conventional angiography was not pursued, as the procedural risks were believed to outweigh the potentially added diagnostic benefits. There were no signs of ICA dissection on MRI or CTA, and extrinsic compression of the sympathetic plexus by the styloid offered a valid explanation for the patient's Horner syndrome. Otolaryngology and neurosurgery consultants believed that with a patent ICA and no cerebrovascular events, the risks of decompressive surgery outweighed the potential benefits. Management included continuation of aspirin, ongoing multidisciplinary follow-up examinations, and CTA to watch for future ICA flow disruption, as well as avoidance of chiropractic neck manipulations and other sudden neck movements. Six months after her initial visit, she remained asymptomatic but had persistent right Horner syndrome. DISCUSSION Eagle syndrome occurs when an elongated styloid process (.30 mm) causes otolaryngological or neurological 387 Copyright © North American Neuro-Ophthalmology Society. Unauthorized reproduction of this article is prohibited. Clinical Observation FIG. 1. Postcontrast T1 axial magnetic resonance imaging of the neck shows focal flattening of the right internal carotid artery (arrow) by the styloid process (arrowhead). symptoms or signs (1). The styloid process is a bony prominence projecting inferiorly from the temporal bone and attaching to ligaments and muscles in the deep neck. It is located between the internal and external carotid arteries, near the lower cranial nerves. Most cases of elongated styloid process are acquired, arising from calcification of the stylohyoid ligament after neck trauma or tonsillectomy, but some cases are congenital (1). Prevalence of elongated styloid process has been estimated at 4%-7.3%, and approximately 4%-10.3% of these patients present with pain (2). Eagle syndrome has 2 main clinical subtypes. The first is the "classic" otolaryngological syndrome with symptoms of a globus sensation and dull unilateral pharyngeal pain, radiating to the ear and exacerbated by swallowing, yawning, and neck movement. The cause is mechanical irritation of lower cranial nerves by the styloid process (3). The second subtype is the "stylocarotid" syndrome, consisting of neck pain and parietal headache radiating to the periorbital region, secondary to mechanical irritation of the ICA (4). The styloid process may compress the sympathetic nerve fibers as they ascend along the ICA, causing Horner syndrome. Focal ICA dissection or atherothrombosis at the compression site may precipitate embolic transient ischemic attacks (TIAs) or strokes, and lateral neck rotation can dynamically occlude or injure the ICA (4-7). One retrospective case-control study identified an association between ICA dissection and styloid process length, with an odds ratio of dissection of 1.08 per millimeter of styloid length, suggesting that ICA dissections relating to an elongated styloid process may be underrecognized (8). Although the overall number of reported cases in the literature of styloid-related ICA dissections is very low, we were unable to find any reports of an isolated Horner syndrome occurring painlessly in this setting. The physical examination in Eagle syndrome may be remarkable for a palpable hard mass (styloid process) in the tonsillar fossa, and palpation of this mass may reproduce pain or a foreign body sensation. Although plain skull radiographs are sufficient to reveal an elongated styloid process, CT head/neck is the best for delineating anatomic relationships in Eagle syndrome. Long-lasting symptom relief in Eagle syndrome requires surgical removal of a portion of the styloid process by either an intraoral or extraoral approach (9). When transecting the styloid process by either method, it is important to avoid FIG. 2. Computed tomographic angiography. A. Coronal view shows elongated styloid processes (arrows) right greater than left. B. Axial projection demonstrates the right internal carotid artery (white arrow) pinned between the styloid process (arrowhead) and the transverse process of the C1 (black arrow). C. Parasagittal image also reveals the right internal carotid artery (black arrow) pinned between the styloid process (arrowhead) and transverse process of C1 vertebra (white arrow). 388 Chang et al: J Neuro-Ophthalmol 2015; 35: 387-389 Copyright © North American Neuro-Ophthalmology Society. Unauthorized reproduction of this article is prohibited. Clinical Observation angulation of the stump because this may injure the facial nerve, which runs lateral to its base. When the ICA is compromised by an elongated styloid process and embolic events may potentially occur, treatment with aspirin or another antithrombotic agent should be strongly considered. We hypothesize that our patient's chiropractic neck manipulations drove the styloid process repeatedly against the already pinned ICA, resulting in damage to the sympathetic fibers but without arterial dissection. There is one published case report of Eagle syndrome causing nondissection-related Horner syndrome (10). That patient had no history of neck manipulations or other neck trauma but developed severe carotid stenosis at the site of compression and suffered a TIA. To our knowledge, our case documents a unique clinical course of Eagle syndrome causing an isolated Horner syndrome through a dynamic "nutcracker" mechanism without significant disruption or dissection of the ICA. STATEMENT OF AUTHORSHIP Category 1: a. Conception and design: C. A. Chang, T. Lin, and J. A. Fraser; b. Acquisition of data: T. Lin, K. Fung, M. Sharma, and J. A. Fraser; c. Analysis and interpretation of data: K. Fung, M. Sharma, and J. A. Fraser. Category 2: a. Drafting the manuscript: C. A. Chang, T. Lin, K. Fung, M. Sharma, and J. A. Fraser; b. Revising it for intellectual content: C. A. Chang, T. Lin, K. Fung, M. Sharma, and Chang et al: J Neuro-Ophthalmol 2015; 35: 387-389 J. A. Fraser. Category 3: a. Final approval of the completed manuscript: C. A. Chang, T. Lin, K. Fung, M. Sharma, and J. A. Fraser. REFERENCES 1. Piagkou M, Anagnostopoulou S, Kouladouros K, Piagkos G. Eagle's syndrome: a review of the literature. Clin Anat. 2009;22:545-558. 2. Costantinides F, Vidoni G, Bodin C, Di Lenarda R. Eagle's syndrome: signs and symptoms. Cranio. 2013;31:56-60. 3. Eagle WW. Elongated styloid process. Report of two cases. Arch Otolaryngol. 1937;25:584-587. 4. 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Head Neck. 2014;36:E136-E138. 389 Copyright © North American Neuro-Ophthalmology Society. Unauthorized reproduction of this article is prohibited.