A case of adult-onset spike-wave stupor associated with hypoparathyroidism and hyperostosis frontalis interna (HFI)

A 34-year-old women without history of seizures was admitted to our hospital because of the diminished responsiveness and the repeated blinking for two days. Her past history showed neither surgery nor inflammation of the thyroid gland. General physical examination was normal. On neurological examination, the patient was blinking frequently and staring without any responsiveness. However, she occasionally became able to respond correctly to verbal orders, such as "open your eyes", "open your mouth", "stand up" and so on, which occurred abruptly just like the switch-on. She was otherwise normal neurologically. The laboratory data showed hypocalcemia, hyperphosphatemia, decreased level of parathyroid hormone and normal renal function, indicating the presence of idiopathic hypoparathyroidism. EEG showed the continuous generalized 2-4 Hz spike and wave complexes with the maximum intensity on frontal lobes. Skull roentgenograms and MRI CT of the head disclosed hyperostosis frontalis interna (HFI) and the compression of superior medial frontal lobes by the HIF. SPECT also showed the diminished circulation and hypometabolism in the superior frontal lobes. Based on clinical and EEG findings, the diagnosis of spike-wave stupor was made. She was successfully treated with valproic acid and ethosuximide. Spike and wave complexes on EEG completely disappeared after administration of alfacalcidole. It is assumed that both hypoparathyroidism and HFI were deeply involved in the development of spike-wave stupor in this adult case.