Narrative review guideline distinguishes episodic ataxia types using clinical features in limited resource settings.

This document functions as a guideline derived from a narrative review, focusing on individuals with confirmed pathogenic variants in KCNA1 and CACNA1A. It specifically targets limited resource-settings where genetic testing is unavailable. The scope involves clinical features distinguishing episodic ataxia type 1 and episodic ataxia type 2, alongside considerations for antiepileptics and acetazolamide. The authors address the critical need for differentiation when molecular confirmation is not readily accessible.

The authors synthesize data on attack duration, symptoms during attacks, and symptoms between attacks. Attack duration less than 10 min for EA1 showed sensitivity 75.3% and specificity 94.0%. Headaches during attacks for EA2 demonstrated specificity 95.7%. Myokymia between attacks for EA1 had specificity 99.6%, while nystagmus between attacks for EA2 had specificity 98.8%. Kinesigenic triggers were more frequently reported in EA1 at 68.4% versus 5.3% for EA2. These metrics support clinical differentiation in the absence of available genetic data.

The authors note that no guideline exists to inform decision-making in settings where genetic testing is unavailable. This review proposes an algorithm for limited resource-settings. However, sample size and absolute numbers were not reported. Clinicians should recognize these limitations when applying the findings to clinical practice. The evidence relies on observational associations rather than randomized trials.