A Man Presenting with Sudden Weakness and Pain of the Right Hand, by Non-Small Cell Lung Cancer with Brain Metastases

ABSTRACT

Unexplained pain and weakness, i.e., without obvious predisposing factors, are often encountered by physiatrists and efforts should be made to determine the cause. A 63-year-old male presented with radiating pain in his right arm and mild weakness of the right hand. An electrodiagnostic examination revealed distal symmetric sensory polyneuropathy in the upper and lower extremities, and denervation potentials in the forearm muscles, which were inconsistent with the cervical spine MRI images and symptoms. A predisposing undiscovered disease was revealed, i.e., squamous cell carcinoma in the lung; brain metastasis affecting the left primary motor cortex was also detected. Therefore, we concluded that the pain and weakness were related to paraneoplastic syndrome and brain metastases of the hand knob. The observed denervation potentials were characterized as trans-synaptic changes in the brain metastasis. This case highlights the importance of unexplainable focal pain and weakness in the increasing prevalence of cancer.