Frequency of Nonconvulsive Seizures among Pediatric Systemic Cancer Patients with Acute Encephalopathy: Emergent Bedside EEG in Resource Constrained Communities

Abstract

Purpose: To determine the incidence of nonconvulsive seizures (NCSz) among children with systemic cancer, who underwent unexplained acute severe encephalopathy (GCS≤8) during admission in ICUs and Neuro-ICUs.
 Study Design: Multicenter prospective observational study describing sub-clinical seizures and electroencephalographic (EEG) features of children (1-16 years) with acute unexplained encephalopathy who underwent emergent bedside EEG≥30min monitoring.
 Material and Methods: We conducted a prospective longitudinal observational study design and EEG assessment of 40 systemic cancer patients age ≤16years, consecutively diagnosed and admitted in intensive care units (ICUs) and neurointensive care units (Neuro-ICUs) of different cancer hospitals with unexplained acute impaired consciousness (GCS≤08) within ≤6hr of such deterioration. Bed-side EEG recordings of ≥30min were done according to the clinical scenario and the requirements of the treating neurologist/intensivist. Patients with brain tumor, brain metastasis, seizures or those with known cause of coma were excluded. Data surrounding clinical, electrographic, and treatment factors were collected Via a prospective systematic review of medical records and EEGs for correlation with diagnosis, change in the diagnosis and management.
 Results: Over a period of 2 years, 40 children, 22.5% 1-5yeras, 37.5% 6-10years, 40% 11-16years; boys 65% and girls 35%, who had systemic cancer with a median age of 9.8 years with unexplained acute deterioration of conscious level (GCS≤08). This cohort underwent bed-side EEG of ≥30 min, which was abnormal in 100% of the records. The main reasons for EEG requests were: 1) unexplained impaired consciousness 22(55%) and 2) reason one plus subtle convulsion 18(45%). The most common EEG abnormalities were invariant mixed theta-delta slowing (27.5%), followed by Low-amplitude delta pattern plus epileptiform discharges (20%) and there was electrographic evidence of EEG seizures in 17(42.5%) of the cohort. These electrographic seizures were present in 55.5% of 18 patients with subtle convulsions, whereas were documented only in 20% of the 22 patients without such movements. Electrographic seizures among patients with subtle convulsions responded to antiseizure drugs in 75% cases as compared 50% such response among patients without such convulsions.
 Conclusion: Emergent bed-side EEG record of ≥30 min is useful in systemic cancer patients admitted in NCUs and Neuro-ICUs with acutely impaired consciousness with or without abnormal body movements. Neurology consultation and EEG studies in these comatose patients provide useful diagnostic information.