Gait Disturbance as an Initial Manifestation of the Paraneoplastic Neurologic Syndrome in a Patient with Lung Cancer

Abstract

We report a patient with clinical presentation of Lambert-Eaton myasthenic syndrome (LEMS) and paraneoplastic cerebellar degeneration (PCD) prior to the diagnosis of small cell lung cancer (SCLC). A sixty-year-old man suffered from subacute dizziness, ataxia, dysarthria, ptosis, and proximal weakness of limbs. A repetitive nerve stimulation (RNS) test showed a decremental responses at low-frequency (LF) stimulation and an incremental responses at high-frequency (HF) stimulation, suggesting the pattern of LEMS. There was no evidence of a specific lesion on brain magnetic resonance imaging (MRI), so we concluded his cerebellar ataxia, nystagmus and dysarthria were caused by PCD. We suspected that the PCD was coexistent with LEMS as a paraneoplastic neurological syndrome (PNS) associated with SCLC. Initial screening for cancer was negative; however, SCLC was detected through computed tomography of the thorax at four-months follow-up. Early recognition of PNS and repeated screening tests can lead to a timely diagnosis and earlier initiation of treatment of SCLC. Keywords: Paraneoplastic syndromes, Nervous system; Lambert-Eaton myasthenic syndrome; Small cell lung cancer