Familial hemiplegic migraine (FHM) is a rare, severe, autosomal dominant subtype of migraine with aura. Up to 75% of FHM families have a mutation in the P/Q-type calcium channel Ca(v)2.1 subunit CACNA1A gene on chromosome 19p13. Some CACNA1A mutations also may cause epilepsy. Here, we describe novel missense mutations in the ATP1A2 Na(+),K(+)-ATPase pump gene on chromosome 1q23 in two families with FHM. The M731T mutation was found in a family with pure FHM. The R689Q mutation was identified in a family in which FHM and benign familial infantile convulsions partially cosegregate. In this family, all available affected family members with FHM, benign familial infantile convulsions, or both, carry the ATP1A2 mutation. Like FHM linked to 19p13, FHM linked to 1q23 also involves dysfunction of ion transportation and epilepsy is part of its phenotypic spectrum.
We studied 94 consecutive patients (age 15 or over) to investigate which aspects of the history and clinical findings help to distinguish seizures from syncope and related conditions. Clonic movements or automatism observed by an eyewitness classified an event as a seizure. The seizure group consisted of 41 patients and the syncope group of 53 patients. The likelihood ratio was used to calculate the predictive power of single findings and logistic regression to analyse combinations of findings. The best discriminatory finding was orientation immediately after the event according to the eyewitness and the age of the patient in the absence of an eyewitness report (P less than 0.001). We found a seizure five times more likely than syncope if the patient was disoriented after the event and three times more likely if the patient was less than 45 years of age. Nausea or sweating before the event were useful to exclude a seizure. Incontinence and trauma were not discriminative findings.
In a prospective study of consecutive patients (age 15 or over) with transient loss of consciousness 45 patients had a history of seizure and 74 patients had a history of syncope. All patients had an EEG, ECG, laboratory tests and a hyperventilation test and were followed for an average of 14-5 months. Epileptiform activity in the interictal EEG had a sensitivity of 040 and a specificity of 0-95 for the diagnosis of a seizure. Epileptiform activity nearly doubled the probability of a seizure in doubtful cases. If no epileptiform activity was found, this probability remained substantially the same. The hyperventilation test had a sensitivity of 057 and a specificity of 0X84 for the diagnosis of syncope. A positive test increased the probability of syncope half as much in doubtful cases. A negative test did not exclude syncope. Laboratory tests were not helpful except for an ECG which was helpful in elderly patients.
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