What is the nose-tapping test for hyperekplexia?

The nose-tapping (Vigevano) maneuver: tapping the tip of the nose at birth triggers sustained non-habituating startle with tonic spasm, breath-holding, and apnea; this is diagnostic; general stimuli also trigger non-habituating hyperekplexic response.

What gene mutations cause hyperekplexia?

GLRA1 (glycine receptor alpha-1): >80% of genetic cases, both AD and AR; GLRB (beta subunit), SLC6A5 (glycine transporter 2), GPHN (gephyrin), ARHGEF9 (collybistin); GLRA1 mutations cause inhibitory glycinergic synapse dysfunction at brainstem/spinal cord level.

What neonatal emergency maneuver prevents death in hyperekplexia?

Flexion maneuver (Vigevano): forcefully flex the head and limbs toward the trunk during a prolonged apneic startle episode; immediately breaks the tonic spasm and terminates apnea; parents must learn this before discharge in affected neonates.

What clonazepam dose treats hyperekplexia?

Clonazepam 0.01-0.1 mg/kg/day (start low, titrate to effect) significantly reduces startle response and apnea frequency; acts on GABA-A receptors to enhance inhibitory tone; most effective treatment; carbamazepine and levetiracetam used as adjuncts.

Does hyperekplexia improve with age?

Neonatal hyperekplexia is most severe and life-threatening; episodes often diminish in severity during childhood; in GLRA1 patients, residual exaggerated startle may persist lifelong but become manageable; adults typically have milder spontaneous startle but remain susceptible to falls.

Hyperekplexia (Startle Disease) Severity and Clonazepam Response

Assesses hyperekplexia severity by startle response intensity, fall frequency, brainstem startle reflex latency, GLRA1/GLRB genotype, and clonazepam dosing response for startle suppression.

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Frequently Asked Questions

What is the nose-tapping test for hyperekplexia?

What gene mutations cause hyperekplexia?

What neonatal emergency maneuver prevents death in hyperekplexia?

What clonazepam dose treats hyperekplexia?

Does hyperekplexia improve with age?