The Lewis- Sumner syndrome (LSS) is a dysimmune multifocal demyelinating sensorimotor neuropathy. It should be considered as a clinical asymmetrical variant of chronic immune demyelinating polyneuropathy (CIDP). LSS is five times less frequent than CIDP whose prevalence is between 2 and 7/ 100,000. Patients with LSS usually present with an asymmetrical involvement of the upper limb with distal sensorimotor deficit in median or ulnar territories. A purely sensory onset with numbness and paresthesia or pain in median or ulnar territory is observed 30% of cases. A lower limb onset is present in 30% of patients with a distal and asymmetrical sensorimotor deficit. Amyotrophy and cranial nerve involvement may be observed in 50% and 20% of patients, respectively. LSS could mimick a nerve entrapment or a vasculitis. The course is progressive or remitting. Electrophysiological pattern associates a multifocal motor demyelination with conduction blocks mostly situated in the forearm. Contrarily to CIDP, other conduction anomalies (reduction of truncal motor nerve velocities, prolonged distal latencies or prolonged F waves) occur rarely outside the blocked nerve territory. Sensory conduction shows a multifocal sensory involvement. Sural nerve biopsy in LSS show elements consistent with a primary demyelination, indistinguishable from that seen in typical CIDP. However nervous biopsy is not necessary to establish the diagnosis. Serum anti-GM1 antibodies are negative and CSF protein content is usually normal or mildly elevated with a mean value of 0.7 g/l. LSS is characterized by a responsiveness to IVIg and steroids. For LSS patients, a treatment similar to that of CIDP, with a first line treatment with intravenous Ig (IVIg) (2g/kg/course), is recommended. Patients who do not respond after 2 or 3 courses should be switched to prednisone; a dose of 1mg/kg/day should be maintained for 4-6 weeks, then slowly tapered.
|Rinsho Shinkeigaku. 2000 Nov;40(11):1126-9.|
[Lewis-Sumner syndrome presenting unilateral quadriceps amyotrophy as an initial symptom]
Second Department of Internal Medicine, Fukui Medical University.
We report a 55-year-old man with a chief complaint of wasting and weakness of the left quadriceps muscle. At age 54, he noticed difficulty in running and weakness in the left thigh, which gradually progressed. On the first admission to our hospital, based on the nerve conduction studies (NCS), the muscle biopsy findings showing neurologenic changes, and no abnormality of spinal MRI, we diagnosed as unilateral quadriceps amyotrophy, which resulted from an atypical form of spinal progressive muscular atrophy. One year later, he showed the bilateral hand weakness, conduction blocks on the right median and ulnar nerves by NCS, and the presence of serum anti-GM 1 antibody. From these findings, Lewis-Sumner syndrome was diagnosed. The therapy of high-dose intravenous immunoglobulin moderately improved his symptoms. It is important to consider Lewis-Sumner syndrome in the differential diagnosis of quadriceps amyotrophy.
|Brain. 2004 Sep;127(Pt 9):2010-7. Epub 2004 Aug 2.|