EPILEPSY SURGERY: OTHER APPROACHES

💈1) Frontal/temporal or occipital craniotomy for resection of a structural epileptogenic focus e.g. Tumour or AVM

🔺This may use stereotaxic localisation (by using a stereotaxic headframe, which may affect the method of intubation)

💈2) Diagnostic placement of surface or depth electrodes

 🔺Mostly only burr holes outlining the future craniotomy flap are used

🔺After placement, the electrodes are externalised and postoperatively patient’s naturally occurring seizures are recorded in conjunction with video monitoring, to register the clinical presentation, with the onset of seizure activity. This recording period may last for several days.

🔺This will be followed by resection of the epileptic focus, on another date.

💈3) Selective amygdalo-hippocampectomy

🔺Here, a cortical incision is made in the anterior temporal lobe and amygdala & hippocampus are resected

EPILEPSY SURGERY- VARIANT APPROACHES🙇🙇🏻🙇🏼🙇🏾: CORPUS CALLOSOTOMY

✔️Suited for patients with atonic or partial seizures with secondary generalisation 

✔️Either the anterior 2/3rd or the entire corpus callosum is divided in the midline

✔️Uses a bifrontal paramedian scalp incision and elevation of the free bone flap, adjacent to the midline in the region of the coronal suture

✔️Injury to the sagittal sinus can result in massive VAE or haemorrhage 

✔️Preserve the numerous bridging veins across the interhemispheric fissure; otherwise, can result in venous congestion and possible infarction 

✔️Right cerebral hemisphere is gently retracted from the falx: this will expose the paired anterior cerebral arteries and corpus callosum

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EPILEPSY SURGERY: SPECIFIC PROCEDURES & HIGHLIGHTS : TEMPORAL LOBECTOMY

✔️ Head turned 90* and held with pins

✔️ Most commonly a "question mark" temporal incision

✔️ a flap based on temporalis muscle elevated

✔️ a subtemporal craniectomy allows visualisation of entire anterior temporal lobe

✔️ anterior 6-6.5 cms of temporal lobe exposed

✔️ surface or depth electrocorticography employed

✔️ map the lesion

✔️ amygdala, hippocampus/ anterior temporal lobe removed 

✔️ Temporal lobectomy involves resection of both lateral and medial (uncus, hippocampal formation etc) temporal structures, mostly under an operating microscope

✔️ Complications: Injury to brainstem, 3rd and 4th cranial nerves , Middle or Posterior Cerebral arteries

✔️ closure of dura, bone flap and scalp concludes the surgery

#epilepsy , #seizures ,#neurosurgery , #EpilepsySurgery , #NeuroAnaesthesia ,#NeuroAnesthesia , #speech ,#wadatest

☁️EPILEPSY SURGERY: BASIC FACTS

☄Most beneficial in partial seizures secondary to a structural lesion

☄For determining the cerebral dominance and hence the location of speech , a WADA test (intracarotid injection of anesthetic to localize language function ; hence invasive) or recently functional MRI mapping (non invasive) of speech centres are done preoperatively 

☄Simultaneous recordings of video EEG and MRI or PET scans can show the epileptogenic focus

☄Temporal lobe surgery may involve:

✔️removal of only the structural lesion & associated epileptogenic cortex

✔️cortical resection alone

✔️excision of amygdala and hippocampus 

✔️removal of the entire anterior temporal lobe (extent of posterior resection dependent on dominance)

✔️depending on the local protocol, intraoperative Electro Corticogram (ECoG) may be used; anesthesia has to be modified accordingly

✔️if speech centre has to be located intraoperatively, an awake craniotomy is required

✔️ So depending on the surgical plan, choice of anesthesia varies