Multifocal inflammatory demyelinating neuropathy with GM-1-antibodies and central conduction failure in a marathon runner

Multifocal inflammatory demyelinating neuropathy (MIDN) is an asymmetric sensory or sensorimotor demyelinating neuropathy not fulfilling the diagnostic criteria for chronic inflammatory demyelinating polyneuropathy (CIDP) or multifocal motor neuropathy (MMN). Evidence of multifocal demyelination and conduction block in motor and sensory nerves can be demonstrated on electrophysiologic examination, patients exhibit a beneficial response to IV immunoglobulin treatment (IvIg). We report a case of a 52 year old male amateur runner with the third relapse of an asymmetric, predominantly motor weakness with some sensory involvement. During the first episode the patient exhibited a sensorimotor deficit of his left arm and leg which was followed by similar symptoms on the right side. The second episode 2 years later consisted of similar motor symptoms and double vision, both episodes were diagnosed as Guillian-Barre-Syndrome and responded to IvIg. A nerve biopsy showed a chronic demyelinating neuropathy. Because of an incomplete recovery no athletic running was possible anymore. Due to increased gait ataxia and falls the patient was admitted again. Nerve conduction velocities were normal, but multifocal conduction blocks were demonstrated with proximal high-voltage-stimulation. In addition to slight clinical signs of spasticity of the legs transcranial and spinal magnetic stimulation revealed prolonged central motor conduction times to all limbs, the somatosensory evoked potentials showed prolonged latencies, both indicating an involvement of the central nervous system. An electromyography study showed neurogenic lesions in all examined muscles. The GM-1-antibody-titer was positive, the spinal fluid findings were normal. As there was a lack of response to steroid therapy, IvIg were given and because of further relapses given periodically all 6–8 weeks since then. The patient recommenced his running exercise and finished a half-marathon in 1:55 hours. Conclusions: MIDN differs clinically and electrophysiologically from CIDP and MMN and can be identified with thorough electrophysiological workup. In addition to MIDN features our patient showed central involvement as an unusual aspect. The recovered athletic abilities of our patient due to repeated IvIg-treatment illustrate that MIDN is a treatable condition.