Objective:

To determine electroclinical-profile and treatment response of precuneal epilepsy

Background:

Epilepsy originating from the precuneus poses diagnostic and surgical challenges owing to its anatomical location within the parietal lobe. Literature describing this entity is limited worldwide.

Design/Methods:

All the patients with precuneus epilepsy who underwent evaluation with or without corrective surgery between 2010 and 2023 are retrospectively included from a tertiary epilepsy centre, South India. All the patient demographic details, aura, seizure semiology, frequency, and control, treatment, radiological, electrophysiological data were noted. Patients who underwent surgery confined to precuneus were compared with cohort of precuneal plus lesions (involving precuneus in-addition to other areas) who underwent surgery in 1:2 ratio

Results:

13 patients (Males 5) with median age of 17yrs. They had heterogenous aura, predominantly sensory (visual, vertiginous, somatic), along with fear, experiential, belching; 4 patients had no aura. Semiologies reported were temporal like in 6, focal tonic 5, focal tonic-clonic 1, generalised tonic 2, bilateral tonic clonic 5, bilateral clonic 2, myoclonic 1. IEDs were from parieto-occipital in 5, temporal in 9, frontal or frontocentral in 5; hemigeneralized 1. Out of 10 patients with ictal monitoring 1 had hypermotor semiology and 9 had  hypomotor with secondary GTCS in 4. Ictal rhythms were deemed localizing in 4; lateralizing in 2 and diffuse in 3. MRI revealed FCD in 7,  vascular malformations in  3, gliosis in 1, DNET in 1, ring enhancing lesion in 1. Surgical intervention was completed in 6(46%)  patients underwent intervention with 3(50%) achieving Engel Ia outcome. HPE showed gliosis in 2, low grade tumors 2, FCD 1, AVM 1. Surgical cohort was compared with randomly selected age matched cases with precuneus plus lesions and underwent corrective surgery in 1:2 ratio, and showed similar results of 50% achieving Engel 1a outcome in both the groups. Of the 7 patients on ASMs, 2 denied surgery, 2 are awaiting surgery; 3 were in complete remission, and 2 having nondisabling aura or seizures. Incomplete resection was noted in 2 patients who were not seizure free post-op

Conclusions:

Precuneus epilepsy can mimic temporal or extratemporal epilepsy similar to parietal-lobe epilepsy owing to its functional connections. Presurgical delineation of this entity did not reveal any distinctive features, but had favourable  surgical-outcome despite anatomical challenges in resection.