Axonal multifocal motor neuropathy without conduction block or demyelination
J.S. Katz, MD;, R.J. Barohn, MD;,S. Kojan, MD;, G.I. Wolfe, MD;, S.P. Nations, MD;, D.S. Saperstein, MD; and A.A.
Amato, MD From the Departments of Neurology, Palo Alto VA Medical Center and Stanford University (Dr. Katz), Palo Alto, CA; University of Kansas Medical Center (Dr. Barohn), Kansas City;
University of Texas Southwestern Medical Center (Drs. Kojan, Wolfe, Nations, and Saperstein), Dallas; and Brigham and Women's Hospital (Dr. Amato), Harvard Medical School, Boston, MA.
Address correspondence and reprint requests to Dr. Jonathan Katz, Department of Neurology (127), Department of Veterans Affairs, 3801 Miranda Ave., Palo Alto, CA 94304; Background: Conduction block is considered an essential findingfor the distinction between motor neuropathies and lower motorneuron disorders. Only a
small number of reports describe patientswith multifocal motor neuropathies who lack overt conductionblock, although in these cases other features of demyelination
still suggest the presence of a demyelinating disorder. In contrast,a purely axonal multifocal motor neuropathy has not been described.
Methods: This report describes nine patients with slowly ornonprogressive multifocal motor neuropathies who had purelyaxonal electrodiagnostic features.
Results: GM1 antibodies titers were normal in all nine cases.Six patients were treated with either prednisone or IV immunoglobulinand three showed
Conclusions: These findings suggest an immune-mediated motorneuropathy with axonal electrophysiologic features that appearsto be distinct from both multifocal motor neuropathy and establishedmotor neuron disorders.
Neuropathies are a significant cause of morbidity worldwide, mainly from diabetes mellitus, HIV infection and leprosy. Many are treatable with
immunosuppression or intravenous immunoglobulin. Tight glycaemic control slows progression of diabetic neuropathy. Even when the underlying disorder is untreatable, making a specific diagnosis and appropriate management to avoid complications and neuropathic pain can be rewarding.