Focal seizures with reversible hypodensity on the CT scan.

Sir: When a postictal abnormal computed tomographic (CT) finding corresponds anatomically to the presumed ictal focus in patients with focal seizures, the abnormality is thought to reflect the existence of a pathological process responsible for the occurrence of the seizures. The CT abnormality is usually not considered to be the result of the ictal and interictal metabolic disturbances which are known to occur in and around the seizure focus. We report a case whose transient postictal focal CT abnormality appears to have been the direct consequence of recurrent focal seizure activity. An 18-year-old right handed student was in good health until ten days prior to admission when he woke up with headache and noted he had bitten his tongue. Three days prior to admission he experienced spontaneous twitching of the right corner of the mouth and the right hand. He was unable to talk during this focal seizure which lasted several minutes. Over the next 12 hours he had four identical focal seizures. Previous medical and family history were unremarkable, blood pressure was 115/70 mm Hg, auscultation of the heart was normal. Neurological examination was normal. A CT scan on the day of admission showed a large hypodense left frontal area without displacement of the lateral ventricle or midline structures (fig). Contrast injection showed a peripheral rim of enhancement. EEG, ECG, chest radiographs, serum electrolytes and full blood count were normal. He was treated with phenobarbitone 150 mg nocte. A four vessel angiogram performed six days after admission showed no abnormalities of the aortic arch, the carotid and vertebral arteries. The intracerebral circulation was normal in the arterial, capillary and venous phases. A presumptive diagnosis of left frontral glioma was made. Three weeks after admission a stereotaxic biopsy under CT monitoring revealed two specimen of normal cerebral tissue. The hypodense area appeared less extensive and a transient right facial weakness was noted after the procedure. One month after admission a CT scan with and without contrast enhancement was normal. Anticonvulsant therapy was gradually withdrawn after twelve months. Over the next two years he remained free of seizures and the CT scan remained normal. This young man's repeated focal seizures suggested an underlying focal pathologic 187