Faculty Bibliography

SUMMARY:: The EEG is helpful in the evaluation of patients with altered mental status and can provide clues for the underlying cause of certain entities. There are few descriptions of the EEG findings in patients with West Nile virus (WNV) infection. We describe the clinical presentation as well as the electroencephalographic findings in five patients with WNV encephalitis. Review of the records of all cases of WNV infection seen at the Mayo Clinic from 1999 to 2003, in which an EEG had been performed. Five patients with WNV encephalitis, in whom an EEG was performed, were found. All the patients had altered mental status and the EEG showed moderate to severe degrees of generalized slowing. Three of the patients had triphasic waves on the EEG. The patients did not have any metabolic disorder or electrolyte abnormalities that could account for these findings. EEG findings in WNV are consistent with an encephalopathic pattern and show varying degrees of generalized slow wave abnormalities and in some cases triphasic waves

We used regression analysis to compare the semiologic features of temporal lobe seizures that occur during sleep (TLS-S) and wake (TLS-W) in the same patient. Most semiologic features correctly lateralized seizure activity during either sleep or wake. No significant differences were found between TLS-S and TLS-W in the 18 semiologic features analyzed. The diagnostic value of TLS-S semiology is similar to that of TLS-W semiology

A 56-year-old woman presented with an acute confusional state and moderate global aphasia. Thyroperoxidase antibody level was elevated (3,890 IU/mL) and SREAT was diagnosed. MRI findings were normal. Cerebrospinal fluid examination revealed only a mildly increased protein. The initial electroencephalogram EEG showed slowing and markedly decreased amplitude over the left hemisphere and left temporal sharp waves. An EEG performed after treatment with intravenous steroids showed a significant improvement of the background slowing, which correlated with clinical improvement. One week later, the patient had an episode of forced head-turning and fencing posture to the right. The EEG shortly afterward showed slowing and a decreased amplitude over the right hemisphere. Continuous EEG monitoring was performed at the time of steroid treatment. Again, there was a significant improvement of the EEG after this treatment that correlated with the clinical condition. SREAT is characterized by fluctuations in mental status and variable EEG findings. These patients often show an excellent clinical improvement to immunosuppressive therapy, including corticosteroids. This case report documents the dramatic clinical and EEG improvement with steroid therapy