Presentation
New onset seizure, found postictal. No significant past medical history.
Patient Data
Initial CT brain imaging at the time of presentation was unremarkable. There is no epileptogenic substrate appreciated and no stigmata of intracranial trauma.
There is symmetric, bilateral, increased, mesial temporal T2/FLAIR signal intensity. There is no mass effect and no diffusion restriction with normal ADC mapping. There is a motion artefact distorting the SWI, however, no associated blooming is suspected suggesting the absence of any hemorrhage. Additionally, sagittal T1 imaging appears normal. Intravenous contrast was not administered.
The limited repeat MRI brain demonstrates the persistent abnormal high T2/FLAIR signal within the mesial temporal lobes. There is no restriction on diffusion imaging and no abnormal enhancement post-contrast administration. There is no hemorrhage on T1 imaging.
Image-guided lumbar puncture yielded anti-NMDA antibodies. All other antibodies were negative.
Infective causes were further excluded.
Case Discussion
Features consistent with autoimmune limbic encephalitis. A lumbar puncture yielded anti-NMDA antibodies to confirm anti-NMDA encephalitis specifically.
Herpes simplex encephalitis was excluded on the bases of an absence of a fever, non-hemorrhagic appearance on MRI and a negative lumbar puncture. A low-grade astrocytoma bilaterally was considered unlikely, however, could not be definitively excluded initially. Gliomatosis cerebri, Hashimoto encephalopathy and neurosyphilis were excluded during clinical and biochemical including lumbar puncture work-up. The patient developed status epilepticus on day 4, and the MRI findings may be compatible with status epilepticus in the presence of a fully negative lumbar puncture.
In view of the strong association with ovarian tumors, the portable ultrasound demonstrated a suspicious right ovary, however no overt confirmation of an incidental ovarian teratoma or other tumor.
Case courtesy of Dr Amaresh I. Ranchod
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