A 3 month old baby born of a third degree consanguineous marriage, came in with the history of recurrent episodes of tonic posturing and stiffness since day 1 of life. Mother noticed that whenever she was tapped on the nose she would become stiff ( The Nose Tap Test). Sometimes the episode was so prolonged, she would get cyanosed. Neuroimaging and EEG were normal. She had also developed an umbilical hernia because of the recurrent stiffening episodes.
The diagnosis was a no-brainer. Hereditary Hyperekplexia however is often misdiagnosed as tonic seizures. I demonstrated the Vigevano manoeuvre to the mother. Forcibly flexing the head and legs towards the abdomen aborts the episode and is life-saving. Response to clonazepam (0.01-0.1 mg/kg) is most gratifying. Combination clobazam ( upto 2 mg/kg) plus clonazepam has been used in refractory cases. Fluoxetine and alcohol has been used in adult. Cannabidiol and ondansetron are under investigation.
A beautiful analysis of 97 patients with genetically proven hyperekplexia yielded some useful genotype -phenotype correlations:https://doi.org/10.1093/brain/awt207
The commonest genetic variants were seen in the GLRA1 gene
Infantile apnoea were common in SLC6A5 mutations
92% of patients with GLRB mutations had delayed speech, even autism
Both GLRB and SLC6A5 were more likely to have developmental delay than GLRA1.
No comments:
Post a Comment