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The H reflex as a diagnostic tool for Miller Fisher syndrome in pediatric patients
B Dachy1, P Deltenre, N Deconinck
1Department of Neurology, CHU Brugmann, Université Libre de Bruxelles, Place A. Van Gehuchten 4, Brussels B 1020, Belgium. bdachy@ulb.ac.be
Abstract:
Miller Fisher syndrome (MFS) is characterized by gait ataxia, external ophthalmoplegia and areflexia. Immunohistochemical studies suggest a pathophysiological role for anti-GQ1b antibodies at the paranodal regions of the oculomotor nerves, at some neurons of the dorsal root ganglia (DRG) and at motor nerve terminals. The variability of abnormal electrophysiological findings reported is significant. Nerve conduction studies, H reflex and F waves were performed in three pediatric patients with MFS. The H reflex was absent in all three patients. It was the sole abnormality in two patients whereas the third patient also had extended motor and sensory nerve conduction impairments. The transient character of this isolated absence has been confirmed in one patient. These data point to a proximal demyelinating process near the DRG. This may involve selective demyelination of Ia spinocerebellar afferent fibers originating in muscle spindles. In a pediatric practice, the H reflex seems to be a useful tool in the diagnostic approach to MFS.
Insights
Miller Fisher syndrome (MFS) diagnosis in children can be aided by the H reflex test. This reflex
Area of Science:
- Neurology
- Immunology
- Pediatrics
Background:
- Miller Fisher syndrome (MFS) is a rare variant of Guillain-Barré syndrome.
- MFS presents with ataxia, ophthalmoplegia, and areflexia, often linked to anti-GQ1b antibodies.
- Electrophysiological findings in MFS are variable, posing diagnostic challenges.
Observation:
- This study evaluated three pediatric MFS patients using nerve conduction studies, H reflex, and F waves.
- The H reflex was absent in all three patients.
- In two patients, isolated H reflex absence was the only abnormality; the third had broader nerve conduction deficits.
Findings:
- The H reflex absence in MFS patients suggests a proximal demyelinating process near the dorsal root ganglia (DRG).
- This demyelination may selectively affect Ia spinocerebellar afferent fibers from muscle spindles.
- The transient nature of H reflex abnormalities was confirmed in one patient.
Implications:
- The H reflex is a valuable and sensitive diagnostic tool for MFS in pediatric neurology.
- Its isolated absence can indicate MFS, guiding further investigation and management.
- Understanding the electrophysiological basis aids in pinpointing the location and nature of nerve involvement in MFS.
