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Published on: March 4, 2014
Evoked potentials in spinal muscular atrophy
Fawzia Cheliout-Heraut1, Annie Barois, Andoni Urtizberea
1Service d'Explorations Fonctionnelles, Hôpital R. Poincaré, CHU Paris-Ouest, Garches, France. fawzia.heraut@rpc.ap-hop-paris.fr
Insights
This study found sensory system abnormalities in children with spinal muscular atrophy (SMA), including delayed visual evoked potentials and altered somatosensory responses. These findings suggest sensory neuron degeneration is more common in SMA than previously recognized.
Area of Science:
- Neurology
- Neurophysiology
- Pediatric Neurology
Background:
- Spinal muscular atrophy (SMA) is primarily recognized as a motor neuron disease.
- Evidence suggests potential involvement of sensory pathways in SMA, but this is less understood.
- Previous reports indicate possible lesions in sensory pathways, including posterior roots and thalamus.
Purpose of the Study:
- To investigate sensory pathway involvement in children with SMA types I and II.
- To compare electrophysiological findings in SMA patients with a control group.
- To assess the prevalence and nature of sensory system abnormalities in SMA.
Main Methods:
- Evaluation of visual evoked potentials (VEPs).
- Assessment of brainstem evoked responses (BERs).
- Measurement of somatosensory evoked potentials (SEPs).
- Comparison of results between 22 children with SMA (11 type I, 11 type II) and a control group.
Main Results:
- Abnormalities were detected across multiple sensory modalities in SMA patients.
- Significant increases in VEP latencies were observed, particularly in SMA type I.
- Alterations in somatosensory thalamocortical responses and delayed central conduction time were noted.
Conclusions:
- The findings suggest sensory neuron degeneration occurs more frequently in SMA than previously assumed.
- Sensory degeneration in SMA may progress slower than motor neuron degeneration.
- Associated brain atrophy could be linked to these sensory pathway changes.
Abstract:
Visual evoked potentials, brainstem evoked responses, and somatosensory evoked potentials were evaluated in 22 children with spinal muscular atrophy, types I and II. Eleven of the children had the severe form of spinal muscular atrophy (type I) and 11 children had the intermediate form (type II). The results of visual evoked potentials, brainstem evoked responses, and somatosensory evoked potentials were compared with those obtained in a control group. Statistical analysis showed abnormalities in the different sensory modalities. A significant increase in the visual evoked potential latencies was observed and was found more often in patients with spinal muscular atrophy type I. Alterations of the somatosensory thalamocortical responses were also observed, as well as a delay in the central conduction time. Although spinal muscular atrophy is usually considered to be a purely motor disorder involving neurons of the spinal anterior horn and nuclei of the lower cranial nerves, lesions of the posterior roots, spinal ganglia, ascending tracts, lateral geniculated corpus, and thalamus have been reported. Our results suggest that sensory neuron degeneration occurs more commonly in spinal muscular atrophy than previously thought and that this process probably develops more slowly than motoneuron degeneration. Such degeneration may be associated with brain atrophy.
