Abstracts

Monogenic forms of epilepsy are rare but are increasingly recognized. Several forms of familial temporal lobe epilepsy have been described; however, a gene has been identified only in Autosomal Dominant Partial Epilepsy with Auditory Features. Hypomagnesemia is known to precipitate seizures and can occur on a hereditary (primary) basis from intestinal or renal wasting. The association between primary forms of hypomagnesemia and epilepsy has not been well-characterized. We describe the clinical and genetic characteristics of a family with primary hypomagnesemia and temporal lobe epilepsy. Four members of the family had serum electrolyte and genetic studies performed. The proband and her sister underwent MRI and EEG studies. This non-consanguineous family has three affected members with primary hypomagnesemia: the proband, a 14 year old girl who presented in convulsive status epilepticus at age 12 years, now has medically-recalcitrant temporal lobe epilepsy; her sister, a 19 year old girl with temporal lobe epilepsy in remission; and her mother, who does not have epilepsy. The proband has frequent complex partial seizures characterized by an aura of diffuse paresthesias progressing to impaired awareness with oral-manual automatisms and garbled speech. The sister had 3 secondarily generalized seizures at age 10. One began with right arm clonic activity. She remained seizure-free on carbamazepine for three years, which was then successfully tapered off. Serum magnesium levels were low for the proband (0.8 mg/dL), sister (1.0 mg/dL), mother (1.0 mg/dL), but normal for the maternal grandmother (2.2 mg/dL); other serum electrolytes were normal. Urine magnesium was 4.5 mg/dL with a fractional excretion of 5%. Interictal EEGs in the proband revealed spike and slow wave discharges in the left frontal region and left temporal slowing in her sister. MRI with epilepsy protocol in the proband revealed bilateral hippocampal signal change on FLAIR and T2 weighted sequences. The sister[rsquo]s MRI was normal. Sequencing of genes known to cause primary hypomagnesemia including the Na+, K+-ATPase gamma-subunit (FXYD2) is in progress. To our knowledge, this is the first description of familial primary hypomagnesemia in association with temporal lobe epilepsy with hippocampal changes on neuroimaging. Genetic disorders known to cause mesial temporal lobe epilepsy should be screened for by molecular and biochemical methods and may have an important impact on treatment and outcome. (Supported by American Epilepsy Society Fellowship (EJF).)