200 Section - Brachial Plexus Palsy and Horner Syndrome Following Cervical Schwannoma Resection: A Two-Case Series with Functional and Electrodiagnostic Follow-Up

Case 1: A 52-year-old man had a long-standing left posterior neck mass that gradually enlarged with tingling in the left upper limb. MRI suggested a cystic lymphangioma, but excision of an 8-cm mass on April 28, 2025 revealed schwannoma with cystic degeneration, followed by left brachial plexus palsy with marked proximal weakness.

Case 2: A 78-year-old woman presented with a left neck mass in 2019. Neck CT showed a 4.6-cm left parapharyngeal lesion suspicious for neurogenic tumor; transcervical excision confirmed benign schwannoma, after which she developed ipsilateral ptosis consistent with iatrogenic Horner syndrome.

Case Description:

Case 1: Immediately after surgery, he had severe proximal left upper limb weakness (MRC 1–2 at the shoulder, about 3 at the elbow, with near-normal wrist strength). Electrodiagnostic studies showed low-amplitude responses in the lateral antebrachial cutaneous, axillary, and musculocutaneous nerves with denervation and later reinnervation in shoulder-girdle and biceps muscles. Postoperative brachial plexus MRI results were compatible with a left C5–C6 root or upper-trunk brachial plexopathy.

Case 2: Postoperatively, she developed Horner syndrome, while limb motor and sensory function remained normal. Persistent ptosis led to corrective eyelid surgery on May 17, 2021.

Discussions:

These cases show that neural complications after benign cervical schwannoma surgery often need ongoing rehabilitation. In Case 1, physical therapy with serial MRC and EMG documented partial reinnervation, but deltoid atrophy caused shoulder instability, prompting orthopaedic referral. In Case 2, persistent ptosis required ophthalmologic surgery, highlighting the rehabilitation physician’s role in monitoring deficits and coordinating multidisciplinary care.

Conclusions:

These cases show that benign cervical schwannoma surgery can cause neural complications, including brachial plexus palsy and Horner syndrome. Surgical decisions should weigh symptom relief against nerve injury risk, while rehabilitation physicians provide ongoing neuromuscular assessment, conservative treatment, and timely multidisciplinary referral to minimize long-term functional sequelae.