Surgery performed by Dr. José Manuel Garbizu
The complete surgery of selective transcortical amygdalohippocampectomy made by the Dr. Jose Manuel Garbizu, from the Gregorio Marañón University Hospital (Madrid, Spain), can be seen in the online surgery app SurgSchoolIn this case, a 39-year-old right-handed patient with drug-resistant temporal lobe epilepsy secondary to left mesial sclerosis is operated on.
La selective transcortical amygdalohippocampectomy This technique is indicated for refractory mesial temporal lobectomy when there is a clear clinical, radiological, and electrophysiological correlation with an identifiable structural lesion, such as hippocampal sclerosis. Compared to standard anterior temporal lobectomy, this approach aims to preserve the lateral temporal neocortex and reduce neuropsychological impact, especially on the dominant hemisphere.
Clinical context and surgical indication
Magnetic resonance imaging showed hyperintensity and volume loss in the head and body of the left hippocampus, findings typical of mesial hippocampal sclerosis. In right-handed patients with a focus in the dominant hemisphere, selective resection allows for maximizing seizure control while preserving language and verbal memory functions, provided that the preoperative study confirms lateralization and concordance.
The main relevant secondary keywords include: mesial temporal epilepsy, hippocampal sclerosis, epilepsy surgery, transcortical approach, and hippocampal resection.
Preoperative planning
The integrated planning:
– High-resolution MRI with temporal oblique coronal slices.
– Prolonged video-EEG study.
– Preoperative neuropsychological evaluation.
– Intraoperative navigation for posterior delimitation (body-hippocampal tail boundary).
In this case, the posterior limit was defined using the lateromesencephalic sulcus as a reference according to the navigator, avoiding excessive resections that compromise non-epileptogenic posterior structures.
Positioning and approach
The patient is placed in the supine position with contralateral head rotation. An arcuate temporal incision and a small circular craniotomy are performed, sufficient to expose the Sylvian fissure and the superior temporal sulcus.
The transcortical approach is performed via a corticectomy of approximately 2 cm in the middle temporal gyrus, at the level of the lower lip of the superior temporal sulcus. This trajectory provides direct access to the temporal horn, minimizing excessive retraction and avoiding transsylvian dissection.
The transcortical approach, compared to the transsylvian approach, reduces vascular manipulation and simplifies the corridor in experienced hands, although it requires anatomical precision to avoid injury from optical radiation.
Key surgical steps
After subpial dissection, the temporal horn is penetrated. Wide exposure of the hippocampal head and body is obtained between the lateral ventricular sulcus, the choroid fissure, and the anterior uncal recess.
A soft retractor allows continuous viewing of the hippocampus without prolonged compression.
The resection begins with the parahippocampal gyrus using a subpial technique, progressing from the lateral ventricular sulcus toward the subiculum and hippocampal sulcus. This subpial plane protects deep vascular structures and limits bleeding.
The posterior limit is established at the body-tail junction, guided by navigation. Excessive posterior resection does not improve outcomes and increases cognitive risk.
The fimbria is then resected to access the dentate gyrus on the medial surface. This step is essential to complete the functional disconnection of the hippocampal circuit.
The main piece is detached by coagulation and sectioning of hippocampal vessels in the hippocampal sulcus. Meticulous vascular control prevents deep bleeding into the ventricular cavity.
Resection of remaining tissue continues towards the inferomedial region. Finally, the uncus is approached anteriorly beyond the free edge of the tentorium, visualizing the cerebral peduncle and third cranial nerve through transparency.
The medial limit of tonsillar resection is established at the entry point of the anterior choroidal artery in the temporal horn, a critical anatomical reference to avoid major vascular injury.
Critical points and risks
Structures at risk include:
– Optical radiations (contralateral superior quadrantanopsia).
– Anterior choroidal artery.
– Cranial nerve III.
– Cerebral peduncle.
– Deep hippocampal vessels.
Systematic subpial technique and constant orientation with anatomical references reduce complications.
Respecting the posterior and medial border is crucial to avoid unnecessary cognitive deficits or catastrophic vascular injury.
Surgical Tips & Pearls
The corticectomy should be minimal but sufficient for a comfortable corridor; unnecessary extensions increase morbidity.
The continuous subpial plane is safer than fragmented dissections.
Confirming anatomical orientation before resecting the uncus prevents disorientation in depth.
Complete resection of the tonsil and hippocampal head and body is key to good seizure control in mesial sclerosis.
Frequent errors
Insufficient resection of the subiculum or anterior uncus may lead to persistent seizures.
Failing to properly define the posterior boundary increases cognitive risk without additional benefit.
Excessive retraction of the temporal lobe promotes edema and visual complications.
Results and monitoring
In mesial temporal lobe epilepsy due to hippocampal sclerosis, selective amygdalohippocampectomy can achieve high rates of seizure freedom (Engel I) when there is diagnostic concordance.
Follow-up includes clinical monitoring, progressive pharmacological adjustment, and comparative neuropsychological assessment.
The preservation of the lateral neocortex in the dominant hemisphere seeks to minimize the impact on language and verbal memory, a central objective in this type of patient.
For whom is this surgery especially useful?
To neurosurgery residents interested in structural epilepsy surgery.
To young assistants who wish to perfect the transcortical approach to the temporal horn.
To neurosurgeons specializing in epilepsy that seek to optimize the balance between radicalism and functional preservation.
