A magnetic resonance imaging (MRI) scan of the brain is performed (Fig. 108.1).

Neuropsychological evaluation reveals normal intelligence, verbal and visuospatial memory. She was shown to be strongly left hemisphere dominant, and Wada test lateralized her verbal functions, memory, and speech to the left side.

• Management steps include the following:
  
  
  
  • Obtaining a full history and clinical examination
    
  • Verifying antiepileptic medication serum levels
    
  • Obtain EEG followed by video EEG telemetry if the EEG was not conclusive.
    
  • Obtain MRI of the brain
    
  • Neuropsychological evaluation
    
  • Wada testing (Dr. Juhn Wada’s intracarotid sodium amobarbital procedure to lateralize speech and memory functions1)

• Figure 108.1 showing a hyperintense signal demonstrates atrophy in the right hippocampus greater than on the left side.
  
• These are characteristic features of mesial temporal sclerosis (MTS).

• As all seizures are coming from the right nondominant temporal lobe along with evidence of right-sided MTS the surgical options are as follows:
  
  
  
  • Corticoamygdalohippocampectomy (temporal lobectomy)
    
  • Selective amygdalohippocampectomy
    
    
    
    • Transsylvian (Yaşargil technique)²
      
    • Transcortical (Olivier technique)³

• According to Wiebe et al.⁴ (the only randomized controlled trial assessing temporal lobe epilepsy surgery as of 2008), the number of patients needed to treat for one patient to become free of disabling seizures is two.
  
• 58% of surgical cases compared with 8% of best medical management cases will be free of disabling seizures.⁴
  
• Long-term favorable seizure outcome (Engel class I and II) ranges between 50–90%.^5,6

• According to the McGill group, 40–58% of patients undergoing temporal lobe epilepsy surgery end up in the Engel Ia class – seizure free.⁶
  
• The chance of becoming antiepileptic drug free according to Téllez-Zenteno et al. is 20%.⁷
  
• Based on the same study 41% will be on monotherapy.⁷

• Complications vary among centers and range between 5–10%.⁴ They include
  
  
  
  • Infections
    
  • Hematoma
    
  • Hemiparesis
    
  • Memory and language deficits
    
  • Contralateral upper quadrantanopia – pie-in-the-sky deficit (Some consider it to be an expected finding rather than a complication.)

• The following summarizes the steps in the temporal lobe surgery and corticoamygdalohippocampectomy^2,3,8:
  
  
  
  • Positioning:
    
    
    
    • The aim here is to have the operative field (frontotemporal area) almost horizontal
      
    • Patient is supine, head in pins, roll under the shoulder.
      
    • The head is kept higher than the heart and turned 60 degrees, slightly extended, and exposing the temple.
      
    • Make sure the neck veins are not compressed or over stretched to avoid compressing the neck veins.
    
    
  • Neuronavigation is used to tailor the skin incision and bony opening.
    
  • Craniotomy:
    
    
    
    • Question mark skin incision from the zygoma just anterior to the ear going back around the pinna and up and parallel to the temporalis line to the hairline
      
    • Then temporalis fascia incision and muscle opening are done.
      
    • Exposure of the pterion, the zygomatic root is performed.
      
    • The craniotomy should reach the anteroinferior-most of the temporal base and then taken to the limits of the skin incision, making sure exposure comprises at least 6.5 cm behind the temporal tip.
      
    • This is followed by controlling the middle meningeal artery and durotomy.
    
    
  • Temporal neocorticectomy:
    
    
    
    • The sylvian vein and especially the vein of Labbé (located 5 to 6 cm behind the temporal tip) need to be protected.
      
    • The middle cerebral artery branches must be avoided.
      
    • This is achieved via a subpial resection of the first temporal gyrus on the nondominant hemisphere and following the pia of the sylvian fissure.
      
    • Posteriorly, the dissection is performed up to the central point or as tailored by functional imaging if the speech area is close by.
      
    • More medially the temporal resection should not reach or cross the petrous ridge and the temporal horn roof (Meyer’s loop) should be avoided.
    
    
  • Amygdalohippocampectomy and parahippocampal gyrectomy:
    
    
    
    • After opening the lateral wall and the lateral part of the roof of the temporal horn one should identify the collateral eminence and the lateral ventricular sulcus.
      
    • Medial to the sulcus is the hippocampus (Fig. 108.2). The fimbria is identified by moving the choroid plexus superiorly and posteriorly (Fig. 108.2).³
      
    • The fimbria and the stria terminalis join, making the anterior border of the choroid fissure (Fig. 108.2).³
      
    • The amygdale should be identified anterior and medial through the temporal horn.
      
    • Using the ultrasonic aspirator the parahippocampus and then the rest of the hippocampal formation is emptied above and below the hippocampal sulcus while holding it with forceps.
      
    • The posterior limit of the hippocampal removal should be at the tectal cistern.
      
    • Care should be taken not to injure the posterior cerebral artery, the basal vein, or the third cranial nerve and cross cerebri medially.
      
    • The dorsomedial limit of removal of the amygdala corresponds to the entorhinal sulcus.
      
    • Intraoperative imaging (if available, such as iMRI or iCT) is particularly helpful to confirm completeness of resection or for reregistration after brain shifts.
      
    • Microscope magnification is very helpful at this stage.

• The central point is the meeting point between the motor (M) and sensory (S) strips (there may be a connecting sulcus in the hand area of the homunculus at that level referred to as “pli de passage fronto-pariétal moyen” of Broca9).
  
• The dotted line indicates extent of resection (Fig. 108.2).

• It represents the part of optic radiation that projects from the relay neurons in the lateral geniculate body (thalamus) forward and lateral.
  
• These projections loop on the roof of the temporal horns all the way just beyond them, anterosuperiorly, then backward toward the occipital visual cortex along the calcarine fissure (Fig. 108.3).^10,11
  
• The loop should be protected during surgery by avoiding the roof of the temporal horns.
  
• For selective amygdalohippocampectomy:
  
  
  
  • Transcortical: through the middle temporal gyrus onto the lateral wall of the temporal horn would be a safe pathway.
    
  • Transsylvian: incisions at the level of the limen insulae, or the adjacent 5 mm of the inferior insular sulcus should be a safe pathway.