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Show Horner Syndrome Associated With Contusion of the Longus Colli Muscle Simulating a Tumor Mohannad Ibrahim, MD, Hemant Parmar, MD, Lynda Yang, MD, PhD Abstract: A 22-year-old man who was discovered unar-ousable after an accidental methadone overdose com-plained of worsening neck pain and left arm weakness over the next week. Examination disclosed a left Horner syndrome and a left brachial plexopathy. Imaging showed a left paraspinal mass adjacent to the sympathetic pathway at the fourth and fifth cervical vertebral levels with imaging features of a tumor. Biopsy was deferred. One month later, the imaging abnormality had nearly disappeared. In retrospect, it represented a contusion injury of the longus colli muscle, a finding not reported previously. Whether it caused the Horner syndrome or was merely a bystander in cervical neck trauma is uncertain. This abnormality should be recognized as a diagnostic confounder. Journal of Neuro-Ophthalmology 2010;30:70-72 doi: 10.1097/WNO.0b013e3181ce1699 2010 by North American Neuro-Ophthalmology Society A22-year-old man was found unarousable with his neck hyperextended after an unintentional methadone overdose. During hospital admission, he reported left arm weakness and pain but was not thoroughly evaluated for these symptoms. One week later, he was admitted for worsening left neck and arm pain. Neurologic examination disclosed mild weakness of left shoulder extension and left elbow flexion and extension. There was hypesthesia over the left C5-C6 dermatomes and reduction of left triceps, biceps, and brachioradialis muscle stretch reflexes. Oph-thalmic examination disclosed fluctuating mild left upper lid ptosis (1.5 mm at most), and pupils measuring 7 mm on the right and 5 mm on the left, both constricting normally to direct light. Topical ocular instillation of 0.5% apraclonidine reversed the anisocoria and produced left upper lid retraction. The clinical diagnoses were left brachial plexopathy and Horner syndrome. Although trauma was suspected, he underwent head and neck MRI. Brain MRI was normal. Dissection protocol (no contrast) neck MRI revealed an unexpected soft tissue lesion in the left prevertebral space at the C4-C5 level that was isointense on T1 and hyperintense on T2 sequences (Fig. 1A-B). Postcontrast CT of the neck, performed 1 day later, showed mild swelling and enhancement at this site (Fig. 1C). Our first impression was of a primary neural or sympathetic chain neoplasm such as schwannoma, neuro-fibroma, or paraganglioma. Mesenchymal neoplasms such as hemangioma, fibroma, or rhabdomyoma were also on the list. We acknowledged that the imaging abnormality did not appear large enough to have caused the brachial plexopathy, but we wondered if a poorly visualized component had infiltrated the plexus. However, no surgical intervention occurred pending further imaging. FIG. 1. Imaging performed at presentation. A. Noncontrast dissection protocol T1 axial MRI shows a lesion (thin arrow) isointense to surrounding muscles at the C4-C5 level in the left prevertebral space in the region of the left longus colli muscle. Compare to normal-sized right longus colli muscle (thick arrow). B. T2 axial MRI shows that the lesion (thin arrow) is hyperintense to surrounding muscles. Compare with normal-sized corresponding structure on the right side of the neck (thick arrow). C. Axial CT of the neck, performed 1 day later, shows that the lesion mildly enhances (arrows). Department of Radiology (Neuroradiology) (MI, HP) and De-partment of Neurosurgery (LY), University of Michigan Medical System, Ann Arbor, Michigan. Address correspondence to Mohannad Ibrahim, MD, Department of Radiology, University of Michigan Medical System, 1500 East Medical Center Drive, Ann Arbor, MI 48109; E-mail: mibrahim@ umich.edu 70 Ibrahim et al: J Neuro-Ophthalmol 2010; 30: 70-72 Photo Essay One month later, neck MRI, this time performed with contrast material, revealed marked lessening of the signal abnormality but with mild patchy enhancement of the longus colli muscle (Fig. 2). In retrospect, the diagnosis was traumatic contusion of this muscle. The diagnostic confusion in this case arose because imaging features of longus colli muscle contusion have not, to our knowledge, been described previously in neck trauma (1,2). In the paraspinal region at the level of C4 vertebra, the sympathetic pathway is surrounded by loose connective FIG. 2. Neck MRI performed 4 weeks later. Precontrast T1 axial (A), T2 (B), and postcontrast T1 (C) MRI images show marked reduction in the swelling and T2 hyperintensity of the lesion, now clearly evident as being within the left longus colli muscle. The affected longus colli muscle (C, arrows) shows mild residual enhancement but is now almost equal in size to the corresponding muscle on the right (C, arrowhead). FIG. 3. Schematic illustration of the anatomic relationship between the carotid sheath (white arrow), sympathetic fibers (black arrow), and longus colli muscles. Our patient had contusive swelling of the left longus colli muscle (large star) with possible compression of the left sympathetic pathway to produce the Horner syndrome. (Modified from Reede DL, Garcon E, Smoker WRK, and Kardon R. Horner's syndrome:Clinical and radiographic evaluation. Neuroimag Clin N Am 2008;18:369-385.) Photo Essay Ibrahim et al: J Neuro-Ophthalmol 2010; 30: 70-72 71 tissue just posterior to the carotid sheath and anterior to the longus colli muscle (Fig. 3) (3). Whether contusive swelling of this muscle caused the Horner syndrome in our patient or was merely a bystander is unresolved. It could not, by itself, have caused the ipsilateral brachial plexopathy. We attribute the longus colli muscle contusion to stretch injury. We report this case to highlight the imaging finding as a diagnostic confounder. REFERENCES 1. Marchini C, Zambito Marsala S, Cavagna E, et al. Saturday night brachial plexus palsy. Neurol Sci 2007;28: 279-81. 2. Kornetzky L, Linden D, Berlit P. Bilateral sciatic nerve ‘‘Saturday night palsy.'' J Neurol 2001;248:425. 3. Civelek E, Karasu A, Cansever T, et al. Surgical anatomy of the cervical sympathetic trunk during anterolateral approach to cervical spine. Eur Spine J 2008;17: 991-5. Photo Essay 72 Ibrahim et al: J Neuro-Ophthalmol 2010; 30: 70-72 |
