By: Andrew Yee
Amygdalohippocampectomy:
Amygdalohippocampectomy is a surgical procedure used to treat all drug-resistant epilepsy
(DRE) that originates in the hippocampus and/or the temporal lobe. The main form of epilepsy
that amygdalohippocampectomy targets is mesial temporal lobe epilepsy (MTLE). Mesial
temporal lobe epilepsy typically results from pathologies in the hippocampus, mainly
hippocampal sclerosis (Estekhareh et al., 2022). Since the seizures occur in the temporal lobe,
the procedure works by removing two parts of the temporal lobe, the hippocampus, and the
amygdala (DocDoc, 2018).
Hippocampus:
The hippocampus is located in the temporal lobe and is a crucial part of the limbic system. The
hippocampus assists in learning, memorizing, and spatial awareness. People with MTLE
experience impaired neurocognitive functions of the hippocampus (Anand & Dhikav).
Amygdala:
The amygdala is also located in the temporal lobe, specifically the medial temporal lobe. It is
part of the neural system and assists in processing and perceiving dangerous and threatening
stimuli (Baxter & Croxson, 2012).
Eligibility:
People who suffer from drug-resistant seizures that have a focal point of the hippocampus or
amygdala are eligible for amygdalohippocampectomy (DocDoc, 2018). Before the surgery a
doctor will determine the location of your seizures, if not already known, by using an MRI, EEG,
or a SPECT to see if you are eligible (Amygdalohippocampectomy).
MRI:
An MRI (magnetic resonance imaging) is a medical device that creates images of your organs
and tissue throughout your body. This is done by using magnets to measure the alignment and
energy of the protons in your body through radio frequency. An MRI is conducted in an enclosed
tube structure and is painless (U.S. Department of Health and Human Services).
EEG:
According to Mayo Clinic, an EEG (electroencephalogram) is a test that measures electrical activity in the brain using small metal disks (electrodes) attached to the scalp. Doctors use EEG’s to detect where overactivity is taking place in the brain.
SPECT:
A SPECT (single photon emission computed tomography) uses a radioactive substance to map
out 3D pictures that show how your organs are functioning. The radioactive tracer often has no
long-term side effects, but can result in soreness from the injection spot or an allergic reaction
(Mayo Foundation for Medical Education, 2022).
Pre-Surgery:
Before the surgery, you should expect neuropsychological exams of vision and memory.
Additionally, blood and urine tests will be administered. The patient will also need to avoid
eating and drinking 8 hours before the surgery, clear any medications with the doctor, and inform
the doctor of any allergies (Shiel, 2020).
Procedure:
The patient will first undergo anesthesia, knocking them unconscious and making the procedure
painless. The surgery starts by tilting the head, followed by the neurosurgeon making an incision
on their skull. They will then access the periosteum and dura and the surgeon will use
neuronavigation systems to reach the temporal gyrus. From there, neurosurgeons will either do
the Cortical, Transylvanian, or Sylvian approach.
● Transcortical: the incision will occur 3.5 cm from the temporal lobe (DocDoc, 2018).
● Transylvanian (SA): the incision will be 15 mm in the temporal stem, preventing damage
to the lateral temporal lobe (DocDoc, 2018).
● Subtemporal: the neurosurgeons will approach the temporal lobe from below and
posterolateral, preserving the inferior temporal gyrus, the temporal tip, the vein of Labbé,
and the ventral bridging veins (Hori et al.).
After the amygdala and the hippocampus have been removed the neurosurgeon will seal up the
incision and replace the bone flap that was removed (Shiel, 2020).
Post Surgery:
The patient will remain in the hospital for 4 days following the surgery under close watch
followed by an immediate follow-up (DocDoc, 2018). In the time following, a CT scan will
occur along with neurological tests to determine the effectiveness of the surgery (Shiel, 2020).
Side Effects:
Like all surgeries, there is a possible risk of cascading effects. These effects usually occur due to
the absence of the hippocampus and amygdala in the brain.
These side effects include:
● Visual perception defects
● Impaired memory functions
● Cerebral vasospasm (narrowing of blood vessels)
● Vascular Spasms (narrowing of arteries caused by the contraction of blood vessels)
● Brain Hemorrhage (popping of a brain artery)
On occasion, some parts of the hippocampus and amygdala are not fully removed which results
in seizures continuing to occur. A second round of surgery may be required (DocDoc, 2018).
Conclusion:
Amygdalohippocampectomy is generally a safe and effective method for stopping temporal lobe
epilepsy. The procedure works by removing the hippocampus and amygdala from your brain in
hopes of stopping your seizures by removing their focal points. There are possible side effects to
the surgery such as memory loss and vision problems, but the surgery can permanently end the
experienced seizures.
Resources:
Amygdalohippocampectomy. The Brain Recovery Project. (2018, March 26). Retrieved December 21, 2022, from https://www.brainrecoveryproject.org/brain-surgeries-to-stop-seizures/amygdalohippoca mpectomy/
Anand, K. S., & Dhikav, V. (2012, October). Hippocampus in health and disease: An overview. Annals of Indian Academy of Neurology. Retrieved December 26, 2022, from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3548359/
Baxter, M. G., & Croxson, P. L. (2012, December 14). Facing the role of the amygdala in emotional information processing | PNAS. PNAS. Retrieved December 26, 2022, from https://www.pnas.org/doi/10.1073/pnas.1219167110
DocDoc. (n.d.). Transforming healthcare, empowering lives. DocDoc. Retrieved December 21, 2022, from https://www.docdoc.com/medical-information/procedures/amygdalohippocampectomy
Estekhareh, S., Saghebdoust, S., Zare, R., Hakak, M., & Hashemabadi, B. (2022, April 22). Memory and executive functioning outcomes of selective amygdalohippocampectomy in patients with hippocampal sclerosis: A preliminary study in a developing country. Surgical Neurology International. Retrieved December 21, 2022, from https://www.semanticscholar.org/
Hori, T., Tabuchi, S., Kurosaki, M., Kondo, S., Takenobu, A., & Watanabe, T. (n.d.). Subtemporal amygdalohippocampectomy for treating medically intractable Temporal Yee 6 Lobe epilepsy. Neurosurgery. Retrieved December 21, 2022, from https://pubmed.ncbi.nlm.nih.gov/8355847/
Mayo Clinic (2022). EEG (electroencephalogram). Mayo Clinic. Retrieved from: https:://www.mayoclinic.org/tests-procedures/eeg/about/pac-20393875
Mayo Foundation for Medical Education and Research. (2022, July 27). SPECT scan. Mayo Clinic. Retrieved December 26, 2022, from https://www.mayoclinic.org/tests-procedures/spect-scan/about/pac-20384925
National Institute of Biomedical Engineering (n.d.). Magnetic Resonance Imaging (MRI). U.S. Department of Health and Human Services. Retrieved from: https://www.nibib.nih.gov/science-education/science-topics/magnetic-resonance-imaging-mri
Shiel, W. C. (2020, June 16). What are the risks and complications of an amygdalohippocampectomy? MedicineNet. Retrieved December 21, 2022, from https://www.medicinenet.com/risks_complications_amygdalohippocampectomy/article.htm
