Case Report: Corpus Callosotomy in a Cat With Drug-Resistant Epilepsy of Unknown Cause.

Daisuke Hasegawa,Yoshihiko Yu,Rikako Asada,Shinichi Kanazono,Satoshi Mizuno,Yuji Hamamoto

doi:10.3389/fvets.2021.745063

Abstract

A 2-month-old, intact male domestic shorthair cat with dullness, bilateral central blindness, and recurrent epileptic seizures was presented to a local clinic. Seizures were the generalized myoclonic and tonic-clonic type. Phenobarbital was initiated and maintained; however, seizures were not controlled. Other anti-seizure drugs, including levetiracetam, zonisamide, and diazepam, also provided insufficient seizure control with seizures occurring hourly to daily. By 8 months of age, the cat displayed non-ambulatory tetraparesis and deep somnolence. Magnetic resonance imaging (MRI), cerebrospinal fluid analysis, and pre- and post-prandial total bile acid analyses were unremarkable. Scalp electroencephalography (EEG) revealed central dominant but generally synchronized spikes and multiple spikes. The cat was diagnosed with drug-resistant epilepsy of unknown cause and was included in a clinical trial of epilepsy surgery. Given the unremarkable MRI and bilateral synchronized EEG abnormalities, a corpus callosotomy was performed at 12 months of age, and partial desynchronization of spikes was confirmed on EEG. Incomplete transection was found in the genu of the corpus callosum on postoperative MRI. After surgery, the mental status and ambulation clearly improved, and seizure frequency and duration were remarkably reduced. Recheck with follow-up EEG and MRI were performed at 3, 6, and 12 months after surgery. Scores of activities of daily living and visual analog scales including cat's and owner's quality of life had also improved considerably. This case report is the first documentation of the one-year clinical outcome of corpus callosotomy in a clinical feline case with drug-resistant epilepsy.

Highlights

The corpus callosum (CC) comprises the largest commissural fibers connecting both cerebral hemispheres, lying in the center of the forebrain longitudinally
The epileptogenic zone of this case was not determined; the project team selected Corpus callosotomy (CCT) as a suitable surgical procedure based on the following reasons: [1] epileptiform discharges distributed bilaterally; [2] unremarkable Magnetic resonance imaging (MRI); [3] severe seizure frequency that might result in decreased mental status; and [4] decreased quality of life (QOL) of the patient and the owner (Supplementary Data 1.1)
This is the first report of CCT in a clinical feline case with drug-resistant epilepsy (DRE) of unknown cause

Summary

INTRODUCTION

The corpus callosum (CC) comprises the largest commissural fibers connecting both cerebral hemispheres, lying in the center of the forebrain longitudinally. At 8 months of age, the cat was further referred to the Veterinary Medical Teaching Hospital of Nippon Veterinary and Life Science University (Tokyo, Japan) to undergo EEG and highfield MRI At this point, seizure frequency increased reaching up to 7–10 sz/d, including GTCS. Other differentials could not be completely ruled out, DRE of unknown etiology was considered the most likely Based on these results, the epileptogenic zone of this case was not determined; the project team selected CCT as a suitable surgical procedure based on the following reasons: [1] epileptiform discharges distributed bilaterally; [2] unremarkable MRI; [3] severe seizure frequency that might result in decreased mental status; and [4] decreased QOL of the patient and the owner (Supplementary Data 1.1). Follow-up MRI at 3, 6, and 12 months after surgery revealed the bisected CC with the remaining genu, loss of caudal part of the left cingulate gyrus, and old hemorrhagic and a necrotic lesion in the left cingulate gyrus likely related to intraoperative tissue handling as well as vascular damage (Figure 2B)

DISCUSSION

Findings

ETHICS STATEMENT