Transorbital endoscopic amygdalohippocampectomy: a feasibility investigation.
OBJECTIVE
Resection of the hippocampus is the standard of care for medically intractable epilepsy in patients with mesial temporal sclerosis. Although temporal craniotomy in this setting is highly successful, the procedure carries certain immutable risks and may be associated with cognitive deficits related to cortical and white matter disruption. Alternative surgical approaches may reduce some of these risks by preserving the lateral temporal lobe. This study examined the feasibility of transorbital endoscopic amygdalohippocampectomy (TEA) as an alternative to open craniotomy in cadaveric specimens.


METHODS
TEA dissections were performed in 4 hemispheres from 2 injected cadaveric specimens fixed in alcohol. Quantitative predictions of the limits of exposure based on predissection imaging were compared with intradissection measurements. The extent of resection and angles of exposure during the dissection and on postdissection imaging were recorded. These measurements were validated with MRI studies from 10 epilepsy patients undergoing standard surgical evaluations.


RESULTS
The transorbital approach permitted direct access to the mesial temporal structures through the lateral orbital wall. Up to 97% of the hippocampal formation was resected with no brain retraction and minimal (mean 6.0 ± 1.4 mm) globe displacement. Lateral temporal lobe white matter tracts were preserved.


CONCLUSIONS
TEA permits hippocampectomy comparable to standard surgical approaches without disrupting the lateral temporal cortex or white matter. This novel approach is feasible in cadaveric specimens and warrants clinical investigation in carefully selected cases.
Department of Neurosurgery and.
H Isaac
HI
Chen
Leif-Erik
LE
Bohman
Laurie A
LA
Loevner
Timothy H
TH
Lucas
D000328:Adult; D000679:Amygdala / Q000601:surgery*; D002102:Cadaver; D003399:Craniotomy; D004724:Endoscopy / Q000379:methods*; D004827:Epilepsy / Q000601:surgery*; D005240:Feasibility Studies; D006624:Hippocampus / Q000601:surgery*; D006801:Humans; D008279:Magnetic Resonance Imaging; D019635:Neurosurgical Procedures / Q000379:methods*; D009915:Orbit
IOF = inferior orbital fissure; SOF = superior orbital fissure; TEA = transorbital endoscopic amygdalohippocampectomy; TONES = transorbital neuroendoscopic surgery; amygdalohippocampectomy; endoscopy; epilepsy; temporal lobectomy; transorbital