Levels of diagnostic certainty for nonepileptic attack disorder in the neuropsychiatry setting

Nonepileptic attack disorder (NEAD) is a medical condition commonly seen in neuropsychiatry services, often as a differential diagnosis of other neuropsychiatric conditions. Recommendations by the International League Against Epilepsy (ILAE) Nonepileptic Seizures Task Force propose a four-level hierarchical approach to the diagnosis of NEAD, based on history, witnessed event, and electroencephalographic (EEG) investigation. We set out to provide the first description of the diagnostic levels of patients with NEAD at a specialist neuropsychiatry clinic. Comprehensive clinical data from 148 consecutive patients with NEAD attending the specialist Neuropsychiatry Clinic run by a single Consultant in Behavioral Neurology were retrospectively reviewed. Patients with NEAD were primarily referred to neuropsychiatry by Consultant Neurologists (n = 94; 63.5%). The majority of patients were female (n = 108; 73.0%), with a disease duration of 7.9 years (standard deviation: 10.4). Anxiety was the most common comorbidity (n = 43; 26.7%). Categorization of patients according to the ILAE Nonepileptic Seizures Task Force criteria was mainly based on clinical features and EEG findings, as only 7 (4.7%) patients had attacks witnessed by a specialist. The largest diagnostic categories were 'possible' (n = 54; 36.5%) and 'clinically established' (n = 40; 27.0%), followed by 'documented' (n = 12; 8.1%) and 'probable' (n = 5; 3.4%). In 125 patients (84.4%), EEGs were performed. Selective serotonin reuptake inhibitors were the most frequently prescribed psychotropic medications (n = 48; 32.4%); 89 patients (60.1%) received behavioral therapy. There were no differences in pharmacological or behavioral management strategies across the patients categorized under different diagnostic levels. Patients with NEAD seen within neuropsychiatry settings are mainly assigned 'possible' and 'clinically established' levels of diagnostic certainty. Difficulty in capturing typical clinical events witnessed by an experienced clinician while on video-EEG can limit the clinical application of the 'documented' diagnostic level. If appropriate, active interventions can be implemented irrespective of diagnostic levels to minimize delays in the neuropsychiatric care pathways.