Electric shock-like sensations in 42 cancer patients: clinical characteristics and distinct etiologies

We retrospectively evaluated 42 consecutive cancer patients manifesting electric shock-like sensations. Fourty three percent presented with Lhermitte's sign (LS), 24% with the previously described outstretching ir. abduction maneuver (OAM) of the arms, and 33% had both phenomena. Twenty nine patients had underlying polyneuropathy related to cisplatin-based chemotherapy in 27 and to thiamine deficiency in 2. Thirtreen patients had myelopathy which was induced by radiotherapy in 11. Patients with polyneuropathy manifested both LS and OAM, while patients with myelopathy more often presented with LS. Neurologic signs suggestive of spinal cord involvement were present in 3 patients with polyneuropathy and in 7 of 11 irradiated patients. MRI disclosed cervical spinal cord swelling in 3 patients with LS. Prolonged cervical latencies on SSER were noted in 5 of 15 patients. All had LS and 3 also had OAM associated with abnormal latencies in the brachial plexi. We conclude that LS and OAM are positive sensory manifestations of increased mechanosensitivity of the damaged central or peripheral sensory axons in the cervico-brachial area. In cancer patients, these phenomena largely manifest treatment-induced myelopathy or polyneuropathy. Auxillary studies help to confirm diagnosis and to depict the uncommon but treatable causes.