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Contributed by: Karla Mora Rodriguez, MD; Pramit Mukherjee, MD; Rebecca Hurst, MD
"Careful interpretation of EEG aided by neuroimaging in the diagnosis of non-convulsive status epilepticus"
An 87-year-old man with history of prior alcohol use disorder presented with altered mentation as a stroke alert. On arrival at the ED, the patient was confused with minimal verbal response, localizing painful stimulus but not following commands. No twitching or involuntary movements were noted. CT head and CTA were unremarkable. Suspicion for unwitnessed seizure and post-ictal confusion prompted an initial load with 3g of intravenous (IV) levetiracetam (LEV) followed by 500 mg twice daily (BID) of maintenance. Routine EEG reported with intermittent slowing in right temporal region but no electrographic seizures. Significant leukocytosis with left shift motivated suspicion for cerebritis/ encephalitis and broad-spectrum antibiotics and antivirals were started. These were discontinued after initial CSF study displayed no evidence of infection. MRI Brain showed T2/FLAIR right inferior temporal hyperintensities with DWI restriction pattern and no contrast enhancement compatible with edema. Persistent disorientation of no clear etiology raised concern for non-convulsive seizures/status epilepticus. Patient was placed on continuous EEG (cEEG) which portrayed multiple focal seizures arising from the right posterior quadrant (RPQ) and right temporal region. Re-read of routine EEG revealed several very subtle brief RPQ seizures. [Fig. 1]. Lorazepam 2 mg IV and LEV 2.5 load were administered. LEV maintenance dose was increased to 750 mg BID (as per creatinine clearance). The patient's intermittent confusion and electrographic focal seizures persisted concordant with focal NCSE. This diagnosis was reached as the seizure burden was >20% of the entire record for a given day. A repeat MRI brain showed interval progression of edema in the right temporal lobe without contrast enhancement and mild edema in the posterior aspect of right thalamus (Pulvinar sign) [Fig. 2]. The following anti-seizure medications (ASM) were added in quick succession while monitoring on cEEG: lacosamide (LCM) 300 mg IV load followed by maintenance of 100mg BID, which was subsequently increased to 200 mg BID, and valproic acid (VPA) load of 2 g and maintenance of 500 mg BID. cEEG progressively improved with the resolution of electrographic seizures by the third day of aggressive ASM therapy. The patient was diagnosed with cryptogenic focal non-convulsive status epilepticus. Subacute Encephalopathy with Seizures in Alcoholics (SESA) syndrome was among the primary differential diagnosis.
Figure 1 Image:
Figure 1 Label: Segment of continuous electroencephalogram (cEEG) in Laplacian montage noting focal onset (arrow) right posterior quadrant electrographic seizure, maximal at P8. Three epochs are shown. Arrowhead marks the seizure end, followed by focal periodic discharges. No clinical correlation was observed.
Figure 2 Image:
Figure 2 Label: MRI of the brain without contrast sequences show hyperintense signal in the temporal and posterior thalamic (pulvinar sign) region in (A) DWI, (B) ADC and (C) FLAIR suggestive of edema. The lack of ADC drop-out rules out acute stroke.
Question 1: Which of the following is most useful in diagnosing non-convulsive status epilepticus (NCSE) in a patient with altered mental status but no overt seizures?
Question 2: Which of the following MRI brain findings is most commonly associated with focal non-convulsive status epilepticus (NCSE)?