Paraneoplastic Neurologic Syndrome in Small Cell Lung Carcinoma

Abstract

A 54-year-old male smoker, previously in good health, was admitted to the hospital due to a tingling sensation in his upper and lower extremities. He reported difficulty walking due to a loss of balance and numbness, leading to an initial diagnosis of chronic inflammatory demyelinating polyneuropathy. Brain and spine magnetic resonance imaging, along with needle electromyography, yielded inconclusive findings. However, a nerve conduction study indicated a length-dependent pattern of sensory-dominant polyneuropathy. A cerebrospinal fluid study did not reveal any specific findings in terms of cell numbers, proteins, or immune tests. Following hospitalization, the patient reported progressive dizziness upon standing, leading to a preliminary diagnosis of orthostatic hypotension. However, a positive anti-Hu autoantibody test, along with chest computed tomography and positron emission tomography scans, revealed a mass in the left interlobar lymph node, suggestive of lung cancer. An endoscopic biopsy confirmed the presence of small cell lung cancer (SCLC). The patient underwent chemo-radiation treatment for the SCLC and immunoglobulin therapy for sensory ganglionopathy. As a result, a definitive diagnosis of paraneoplastic neurologic syndrome was made. Although such cases are rare, our observations suggest that symptoms of dysautonomia and sensory ganglionopathy may be associated with the production of anti-Hu antibodies.