The left and right hemispheres of the brain are broadly responsible for different functions, and a Wada test is performed to map out memory and language function in the individual hemispheres. In a sense, Wada is an extension of the neuropsychological evaluation, and aims to determine whether the proposed surgery on the patient would result in significant memory deficits. This procedure also determines which hemisphere language function is fundamentally represented. Wada is invasive: each hemisphere is anesthetized in sequence using a short acting barbiturate through a catheter inserted in the femoral artery in the groin, and the ‘awake half’ of the brain is tested for language, memory, and learning function. With the advance of technology and availability of newer noninvasive methods, our use of Wada has decreased over the years.
Information for patients
Wada testing is occasionally performed to determine, in a direct way, which half of the brain is more important for language and memory. This test is only done for patients who are confirmed as candidates for surgery, and normally follows all other testing. If Wada testing is recommended, you will have the option of a thorough discussion with our team about why it is being recommended, and what exactly is involved in the procedure. In general, the Wada test involves putting one half of the brain to ‘sleep’ temporarily with an anesthetic injection, so that the function of the ‘awake’ half can be tested in isolation. After the ‘asleep’ half of the brain recovers fully – usually in about 30 minutes – the other half is tested in the same way. Results of the Wada test are discussed in detail in our patient management conference, and a final plan about epilepsy surgery is then made.