Idiopathic Spinal Accessory Neuropathy: A Case Report
Correspondence Address: Source of Support: None, Conflict of Interest: None DOI: 10.4103/0028-3886.314589
Source of Support: None, Conflict of Interest: None
Isolated spinal accessory neuropathy (SAN) is an uncommon motor neuropathy most often related to local surgical procedures at the posterior cervical triangle, such as lymph node biopsy or tumor excision. Rare causes, such as nerve injury during carotid endarterectomy or catheterization of the internal jugular vein, after acromioclavicular or sternoclavicular dislocations, or penetrating injury due to trauma are also mentioned. In the case of unknown etiology, the term idiopathic SAN is used.,
A 74-year-old man was reviewed due to 4-month history of right shoulder weakness and deep scapular pain. As shown in [Figure 1], ipsilateral droopy shoulder, prominent levator scapulae muscle, scapular winging accentuated by shoulder abduction and head-tilt to the contralateral side were evident. Moreover, the right genioglossus muscle was unaffected; thus Collet-Sicard syndrome was excluded. Furthermore, Ear, Nose and Throat evaluation consisting of oral examination and laryngoscopy revealed normal palatal and vocal fold mobility excluding Schmidt syndrome.
Electromyography (EMG) sampling exhibited active chronic neurogenic changes (a. fibrillations, positive sharp waves +3, b. motor unit action potentials [MUAPs] of moderately increased amplitude and duration and normal or increased number of phases and c. severely reduced recruitment of MUAPs) from the right trapezius and sternocleidomastoid muscles. EMG findings from the ipsilateral genioglossus, serratus anterior, rhomboid major, infraspinatus, deltoid, biceps brachii, triceps brachii and 1st dorsal interosseous muscles were unremarkable.
Cervical spine, neck, brain and skull base MRIs with and without contrast could not identify underlying structural pathology that could explain the patient's symptoms. Cerebrospinal fluid and extensive blood testing, including full blood count, erythrocyte sedimentation rate, C-reactive protein, immunoelectrophoresis and immunofixation, were also normal. Neither trauma nor history of related surgical procedures or infection was mentioned. Thus the diagnosis of idiopathic SAN was confirmed.
Idiopathic SAN is an exceedingly rare motor mononeuropathy. To our knowledge, only a few cases are reported in the literature., In contrast to the cases reported by Sergides et al. and Gürsoy et al. where the trapezius muscle was only involved, in our case both trapezius and sternocleidomastoid muscles were wasted.
Idiopathic SAN diagnosis is based on the combination of clinical, electrophysiological, blood and MRI testing. Management is nonoperative involving analgesia and physiotherapy to strengthen trapezius and build up adjacent shoulder stabilizing muscles. Prognosis is unclear, though full recovery is possible.
We would like to thank the patient and his family for providing full consent to publish this case.
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