Vision test

Schmeiser B, et al. Epilepsy & Behavior 76(2017):39-45.

Purpose

Surgery can be a cure for certain types of focal epilepsy. However, possible side-effects may scare people from seeking surgery. It’s important to understand the potential risks, as well as how to lessen them, to determine whether surgery is the best option.

This study compared risks of different surgical procedures for seizures arising in the temporal lobe. Specifically, the risk of visual field defects (loss of part of the usual field of vision) was looked at with respect to driving, since the ability to drive may be one of the main motivations for undergoing surgery.

Description of Study

  • The study included 366 people at one epilepsy center in Germany.
  • One of four surgical procedures was performed on each person:
    1. Complete removal of front portion of temporal lobe.
    2. Partial removal of front portion of temporal lobe.
    3. Selective surgery removing part of the amygdala and hippocampus (involved in memory and emotions) - approached from natural opening above temporal lobe.
    4. Selective surgery removing part of the amygdala and hippocampus (involved in memory and emotions) - approached from natural opening below temporal lobe.
  • Of 366 people, 276 had visual field tests before and after surgery to assess visual field defects and if they interfered with driving ability (driving-relevant defects).

Summary of Study Findings

  • The surgical procedures had different risks of causing general visual field defects.
  • The selective surgery (approach below temporal lobe) had the lowest risk. Percentage of people with postoperative visual field defect by procedure:
    1. 83% - complete removal of front portion of temporal lobe
    2. 60% - partial removal of front portion of temporal lobe
    3. 74% - selective surgery (approach above temporal lobe)
    4. 56% - selective surgery (approach below temporal lobe)
  • The selective surgery (approach below temporal lobe) had the lowest risk for visual field defects that could affect driving. Percentage of people with driving-relevant visual field defect by procedure:
    1. 58% - complete removal of front portion of temporal lobe
    2. 43% - partial removal of front portion of temporal lobe
    3. 48% - selective surgery (approach above temporal lobe)
    4. 21% - selective surgery (approach below temporal lobe)

What does this mean?

  • There are many important considerations when selecting treatment options for epilepsy.
  • Since the ability to drive is an important aspect of most of our lives, it is important to consider the risks for visual field defects from different surgical approaches.
  • If there is a choice of surgical approach for temporal lobe epilepsy, this study suggests that a below-temporal-lobe approach selective surgery has the lowest risk of visual field defects in general and for those that may affect driving.

Article published in Epilepsy & Behavior, November 2017.

Authored By: 
Nicholaus Pfeiffer
Authored Date: 
02/2018
Reviewed By: 
Joseph I. Sirven MD
on: 
Wednesday, February 7, 2018