Radiologic Findings in Acute Necrotizing Encephalitis

Acute necrotizing encephalitis is a viral disease affecting the central nervous system and other organs. It is differentiated from other viral encephalitides by its predilection for involvement of cingulum, fornix, hippocampus, the temporal cortex, and less frequently the cortex of the occipital lobe and the insular region of the frontal lobe (1). In approximately 50 per cent of the cases unilateral temporal lobe involvement is revealed at autopsy (2). Nine cases showing radiologic findings have been reported (3–5), in 2 of which the patient survived. One additional case with radiologic findings will be reported in this paper. As it has been suggested that temporal lobe decompression may be a significant factor in survival (2), it seems important that radiologists should become aware of the clinicoradiologic picture associated with this disease. The findings of a temporal lobe mass in our case, as in those previously reported (except one in which a frontal lobe mass was found (6», are not specific for this disease. They consist of elevation and medial displacement of the middle cerebral artery and stretching of the cisternal part of the anterior choroidal artery on the arteriogram (Fig. 1), with corresponding displacement of the basal vein and temporal horn of the lateral ventricle on the venogram and air studies, respectively. These findings could be produced by any infiltrating space-occupying lesion in this site. On a radiographic basis alone differentiation from abscess or infiltrating tumor would be impossible. Case Report On Jan. 1 or 2, 1961, E. M., a 69-year-old white female, suffered a sore throat with headache, malaise, nausea, and vomiting. Since Jan. 3 her temperature had ranged from 100 to 102 degrees. On Jan. 4 the patient became progressively more confused and disoriented. On Jan. 6 meningismus developed, and the patient became semicomatose. Bilateral Babinski reflexes were noted. Skull films at this time revealed no abnormality. Shortly after admission to Good Samaritan Hospital on Jan. 8, convulsive twitching of the right arm and shoulder was exhibited. Spinal tap showed an opening pressure of 310 mm with 69 lymphocytes, 2 red blood cells, and protein 146 mg per 100 ml. Complete general physical examination the following day disclosed these positive findings: 1+ to 2+ stiff neck, involuntary eye movements, slightly sluggish response of pupils to light and accommodation, absent patellar, Achilles, and abdominal reflexes bilaterally, and bilateral positive Babinski reflex. Repeat lumbar puncture on Jan. 9 revealed an opening pressure of 350 mm of water with 150 white blood count containing 1 per cent polymorphonuclear cells and 90 per cent lymphocytes, 3 red blood cell count.