TABLE 15.3 DRUGS AND TOXINS THAT MAY CAUSE ATAXIA Benzodiazepines Alcohol Dextromethorphan Marijuana and synthetic cannabinoids Phenytoin Carbamazepine Tricyclic antidepressants Antihistamines Lead 5-Fluorouracil Ethylene glycol Primidone Phenothiazines Topiramate Risperidone Gabapentin Phenobarbital GBS is a postinfectious polyneuropathy with a peak incidence at ages to years that can cause ataxia, and must be considered in a patient presenting with areflexia and weakness, particularly the classic presentation of ascending paralysis and weakness CSF analysis, particularly assessing for elevated protein in the CSF, is key in diagnosing GBS The clinician must also consider Miller Fisher variant, which has more severe and more rapid onset than GBS, and classically presents with ataxia, areflexia, and ophthalmoplegia CSF pleocytosis can also be seen with this illness; however, for definitive testing and diagnosis, neurology consultation should be considered A rare but severe cause for acute ataxia is stroke , either hemorrhagic or ischemic Cerebellar bleeding in children can be associated with arteriovenous malformations or cavernous hemangiomas and often presents with severe headache and signs of increased intracranial pressure (ICP) Posterior circulation