Jones, Felipe J.S.

BACKGROUND Differential awakening is a well-known, yet poorly understood phenomenon seen in patients with intracranial pathologies. Because acute postoperative neurological decline has many potentially reversible causes, distinguishing differential awakening from other etiologies is critical. To the authors’ knowledge, differential awakening has not been reported following peripheral nerve procedures. OBSERVATIONS A 40-year-old man presented with a 1.5-year history of painful bilateral cervical and right lumbosacral radiculoplexus neuropathy recently associated with bilateral facial and vestibulocochlear neuropathy. He had not responded to treatment trials. A sciatic nerve lesion in the sciatic notch was identified on imaging and an open biopsy of the posterior femoral cutaneous nerve was pursued. Immediately after emergence from anesthesia, he demonstrated a complete inability to dorsiflex or plantar flex the right foot, despite minimal intraoperative manipulation of the sciatic nerve. Over the ensuing hour, motor function progressively returned to baseline. The transient postoperative motor deficit was attributed to differential awakening of the sciatic nerve. Pathological analysis confirmed high-grade B-cell lymphoma. LESSONS Differential awakening may be an underrecognized cause of transient neurological worsening during emergence from anesthesia following peripheral nerve surgery. Further investigation is needed to clarify the underlying mechanisms and define its incidence and risk factors. https://thejns.org/doi/10.3171/CASE251028

ABSTRACT Background Monoclonal gammopathy‐associated myopathies (MGAMs) include light chain (AL) amyloid myopathy, sporadic late‐onset nemaline myopathy (SLONM), and vacuolar myopathy with monoclonal gammopathy and stiffness (VAMMGAS). These subtypes usually occur separately, although rare overlap has been described. We report a patient with monoclonal gammopathy and concurrent SLONM and excessive glycogen accumulation, resembling VAMMGAS but with distinct features. Methods Case report with clinical, electrophysiological, pathological, and therapeutic characterization of a patient with IgG‐kappa monoclonal gammopathy and coexisting SLONM and glycogen accumulation within muscle fibers. Results A 69‐year‐old man developed subacute progressive axial and limb weakness, head drop, dysphagia, and weight loss. Examination showed proximal/distal weakness, neck extensor weakness, and lumbar hyperlordosis. EMG revealed myopathic motor unit potentials without electrical myotonia or complex repetitive discharges. Serum studies identified IgG‐kappa monoclonal protein with elevated kappa light chain and ratio. Muscle biopsy demonstrated nemaline rods (1% of fibers) and scattered fibers with non‐rimmed vacuoles (0.3% of fibers) containing PAS‐positive, diastase‐labile material consistent with concurrent SLONM and glycogen storage myopathy‐like pathology. Genetic testing for congenital nemaline and glycogen storage myopathies was negative. Plasma‐cell directed therapy with daratumumab, lenalidomide, and dexamethasone led to rapid functional improvement and M‐protein reduction. Further gains followed autologous stem cell transplantation. Conclusion This case expands the MGAM spectrum, highlighting co‐occurrence of SLONM and an excessive glycogen accumulation responsive to immunotherapy and transplantation. These findings suggest a spectrum of related disease processes. Recognition of this combined pathology is clinically important, as affected patients may benefit from targeted immunotherapy or stem cell transplantation.