Wada test

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The Wada test is used in neuropsychology to determine in which hemisphere certain functions are located. It is named after the Japanese-Canadian neurologist, clinical neurophysiologist and epileptologist  Juhn Atsushi Wada .

Execution and goal

In some epilepsies that cannot be successfully treated with medication, an operation can lead to freedom from seizures or at least a significant improvement in the frequency of seizures. A prerequisite for such an epilepsy surgical intervention is that the area of ​​the brain that is responsible for the occurrence of the seizure can be reliably identified and that its removal does not lead to any or at least no serious damage. The Wada test can help clarify the last question.

For the test, a catheter is usually placed from an artery in the groin as access to the blood vessels of the brain. This is then pushed over the aorta into the internal carotid artery (carotid artery), sometimes even further into the brain. A contrast agent is injected into the brain through the catheter to make the blood vessels in the brain visible.

The drug amobarbital is then injected into one of the two halves of the brain, which temporarily anesthetizes it. A simple test is used to check whether the function of the half of the brain is really lost: the patient had both arms raised before the drug was administered; When the injected agent takes effect, the arm whose associated cerebral hemisphere was "switched off" sinks down, the other remains raised.

Next, the patient is asked several questions and arithmetic tasks, pictures are shown and his speech is tested.

After the anesthesia has subsided, the patient is asked again about the tests:

  • Can he still remember the picture?
  • Does he still know the arithmetic problem and its solution?
  • How was his language during and after the test?

The answers can be used to decide whether an operation can be performed. If, for example, memory is severely impaired, this indicates that the other half of the brain can no longer absorb memory content. The patient should expect to suffer from memory impairment after the procedure, even if the seizures could be successfully controlled by it.

literature

  • J. Wada, T. Rasmussen: Intracarotid Injection of Sodium Amytal for the Lateralization of Cerebral Speech Dominance. Experimental and Clinical Observations. In: J Neurosurgery. (1960), pp. 266-282. PMID 17564192
  • DW Loring, KJ Meador, GP Lee, DW King: Amobarbital Effects and Lateralized Brain Function. The Wada Test. Springer Verlag, New York / Berlin / Heidelberg 1992, ISBN 0-387-97738-4 .
  • M. Kurthen: The determination of cerebral speech dominance with the intracarotid amobarbital test. In: Fortschr Neurol Psychiatr. (1993) 61 (3), pp. 77-89. PMID 8477921
  • M. Hajek, A. Valavanis, Y. Yonekawa, R. Schiess, A. Buck, HG Wieser: Selective amobarbital test for the determination of language function in patients with epilepsy with frontal and posterior temporal brain lesions. In: Epilepsia. 39 (1998), pp. 389-398. PMID 9578029

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