Status epilepticus as a risk factor for postencephalitic parenchyma loss evaluated by ventricle brain ratio measurement on MR imaging.

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.