Predictive Values of Electroencephalography (EEG) in Epilepsy Patients with Abnormal Behavioural Symptoms

Abstract

Background: Psychiatrics usually refer patients for electroencephalography (EEG) when they suspect that a mental illness has an organic cause. Nonconvulsive seizures may mimic functional psychiatric illness when they manifest with abnormal behaviours. These seizures may be misdiagnosed by clinicians without EEG. This has major implications for psychiatry practice in a developing country like Nigeria where seizures and other potentially preventable organic brain syndromes are common. Despite its limitations, the EEG has been useful in evaluating psychiatric patients with suspected seizures. This study determined the predictive value of EEG in epilepsy patients with abnormal behaviours.

Methods: The electroencephalograms (EEGs) of 337 consecutive patients with epilepsy manifesting with abnormal behaviours were studied at FNPH Kaduna, from January 2011 to October 2013.

Results: There were 220 males and 117 females with respective mean ages of 22.8 (SD 15.9) and 22.1  (SD 16.0) years. The age ranges 21-30 years and 0- 1 year old formed the most and least populous age  groups respctively . Based  o  symptomatology, patients were categorized into five seizure groups: simple partial, complex partial, complex par t ial secondar i ly generalised, primarily generalised toni c - c loni c and absences . Epileptiform abnormalities in the form of polyspikes, spikes and waves were: bilateral, synchronous and symmetrically generalised (40.0%); localised to a cerebral hemisphere (42.1%); and focal with secondary generalisation in 15% patients respectively. 10 patients had bi lateral , symmet r ical ly generalised 3Hz spike and wave complexes, while 7 patients had normal EEG

Conclusion: The EEG identified sources of seizures in epilepsy pat ients wi th nonconvulsive behavioural symptoms.

Key words: Abnormal behaviours, electroencephalography, epilepsy, nonconvulsive seizures.