A study at the Royal North Shore Hospital in Sydney whose authors include well-respected neurogeneticist, Associate Professor Carolyn Sue, investigated peripheral nerve abnormalities in SPG4 HSPers.
Peripheral nerves are all the nerves in the body outside the brain and spinal cord.
Peripheral neuropathy means that certain peripheral nerves are damaged and don’t work properly.
Peripheral neuropathy in HSP tends to affect the nerves in the feet and legs. Symptoms include weakness or clumsiness of movement (motor); unusual or unpleasant sensations such as tingling or burning; reduction in the ability to feel texture, temperature, etc.; and impaired balance when standing or walking (sensory).
To identify peripheral nerve abnormalities in hereditary spastic paraplegia (HSP) due to mutations in the spastin gene (spastic paraplegia 4, SPG4) using standard nerve conduction (NCS) and novel tests of axonal excitability.
Eleven patients with known mutations in spastin were assessed with NCS for the upper and lower limbs, and axonal excitability testing on the median nerve.
Standard nerve conduction studies revealed a sensorimotor neuropathy in two patients. Excitability studies on median motor axons showed an isolated abnormality (increased strength-duration time constant), but those on sensory axons were normal in nine patients with normal routine nerve conduction studies.
Peripheral neuropathy occurs in HSP patients with SPG4 mutations, but axonal excitability studies provide limited additional evidence for subclinical peripheral nerve dysfunction, and add little further to standard nerve conduction studies.
The features of HSP due to SPG4 mutations include sensorimotor polyneuropathy. The value of excitability studies is limited in individual patients.
SOURCE: Clin Neurophysiol. 2012 Jul;123(7):1454-9. Epub 2011 Dec 21. Copyright © 2011 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved. PMID: 22192498 [PubMed – in process]
Peripheral neuropathy in hereditary spastic paraplegia due to spastin (SPG4) mutation–a neurophysiological study using excitability techniques.
Kumar KR, Sue CM, Burke D, Ng K.
Department of Neurology and Clinical Neurophysiology, Royal North Shore Hospital, St Leonards, NSW 2065, Australia.