Background and purpose: Cerebral atrophy following herpes simplex encephalitis has formerly been described. We aimed to quantify atrophy after encephalitis of various causes. Additional objectives were to define which initial or long-term clinical factors correlate with volume loss and to search for any correlate in global clinical outcome measures.
Methods: MR imaging was performed in 40 subjects in the acute stage of encephalitis and > or =6 months after onset of symptoms. The ventricle brain ratio (VBR) was measured on corresponding images from disease onset and follow-up, and the change in VBR (VBR delta) was calculated as a percentage value of the starting measure. Clinical outcome was evaluated by interview and neurologic examination and characterized by using an encephalitis-adapted version of the modified Rankin Scale.
Results: The VBR delta ranged from -5%-102% (median, 5.93%; lower quartile, 1.8%; upper quartile, 14.55%; mean, 14.43%; SD, 23.75%). We found significant differences in the VBR delta between those patients who required intensive care (P = .027), had more than 2 epileptic seizures or a status epilepticus during the acute stage (P = 0.021), or developed postencephalitic epilepsy (P = .015) and their respective counter-subgroups. Three patients were rated to have unfavorable outcome (modified Rankin Scale, 3-5). Patients with unfavorable clinical outcomes tended to show greater VBR delta values, but a statistical evaluation was impossible because of small numbers.
Conclusion: More than 2 epileptic seizures or a status epilepticus during the acute stage of encephalitis is associated with a greater loss of parenchyma.