An ataxia of not so obvious cause

Objective: Describe the diagnosis of a familial hemiplegic migraine (FHM) with ataxia starting from the suspicion of a symptomatic cerebellar lesion after perinatal heart surgery. Methods: A 2-year-old girl visits Neuropediatrics for presenting episodes of fainting followed by crying associated with mild cranial trauma; an equivalent of breath-holding spells was suspected. Among her personal pathological antecedents, she presents a complex congenital heart disease operated on 6 days after birth, with 3 months NICU hospitalization. Early stimulation program starts when discharged, observing a motor developmental delay with non progressive ataxia attributed to her antecedents. Due to the anesthetic risk and ataxia with apparent improvement, in agreement with the parents, the MRI was delayed until the age when she did not require such sedation. Several EEGs were performed with normal results and cardiac arrhythmias were excluded after Holter monitoring. When she is 6-year-old presents a clinical picture compatible with acute encephalitis after a minor head trauma 24 hours before, preceded by headache and hemiparesis (CT scan normal). She needs PICU care for 7 days with complete recovery. Flunarizine therapy was initiated. MRI and genetic study confirmed the diagnosis. Results: ATP1A2, SCN1A were normal; CACNA1A shows pathogenic variant c.653C>T; p.Ser218Leu at exon 5, previously described in FHM. Parents were studied and showed no mutation. Brain MRI shows mild cerebellar vermis atrophy, also described in this patients . Conclusion: The patient's personal history misdiagnosed the true underlying cause of paroxysmal episodes and motor developmental delay. This case remembered us that what can be explained only by a cause is the most probable etiology of apparent unrelated signs.