Assessment of cerebral blood flow changes in nonconvulsive status epilepticus in comatose patients: a pathophysiological transcranial Doppler study

Abstract

Purpose: We assessed the accuracy of transcranial Doppler (TCD) in helping to diagnose nonconvulsive status epilepticus (NCSE) in comatose patients admitted to the intensive care unit (ICU) for acute neurological disorders at high risk for NCSE.

Methods: A 2-year prospective observational study in 38 consecutive patients requiring continuous electroencephalography (EEG) monitoring and intracranial pressure monitoring with TCD.

Results: Of the 38 patients, 10 (26.3%) had NCSE by continuous EEG monitoring. Bilateral mean and maximal systolic and diastolic TCD velocities were significantly different between patients with and those without NCSE. Areas under the receiver-operating characteristic (ROC) curves of mean and maximal systolic velocities by TCD were 0.82 (95% CI, 0.64-1.00) and 0.79 (95% CI, 0.62-0.95) with cutoffs of 95 cm/s and 105 cm/s, respectively. Areas under the ROC curves of mean and maximal diastolic velocities were 0.76 (95% CI, 0.56-0.95) and 0.78 (95% CI, 0.60-0.96) with cutoffs of 31 cm/s and 40 cm/s, respectively. For none of the velocity parameters did the areas under the ROC curves differ significantly between the left and right sides. The best performance was obtained using mean systolic (SV) and a cutoff of 95 cm/s, which yielded a positive likelihood ratio of 3.8 and a negative likelihood ratio of 0.25.

Conclusion: Our preliminary results showed a significant association between increased TCD velocities and NCSE in comatose patients. However, the likelihood ratios suggested a limited role for TCD in helping to diagnose seizure activity. Further studies with larger samples of NCSE patients are warranted to determine the exact contribution of TCD for NCSE detection in comatose ICU patients.

Keywords: Electroencephalography; Intensive care units; Neurological; Transcranial Doppler sonography.