By: Nazneen Khan
The WADA Test: A Brief Overview of an Essential Tool Used in Epilepsy Surgery
The WADA test is a preoperative medical procedure performed on epileptic patients. It assesses the memory and language abilities of the brain; thus, it is used as a tool before major brain surgery. This diagnostic tool is an invasive procedure where a catheter is inserted in the internal carotid artery and an anesthetic drug is injected thereafter. Several steps are taken before and after the procedure by medical personnel. Though some risks are associated with it, the test is generally useful in its ability to assess memory and language functions in an epileptic patient.
What is the WADA Test?
The WADA test is essentially a pre-surgical evaluation of the brain, which helps surgical teams determine which side of the brain is dominant for language capabilities and memory functions (Downstate Health Sciences University, n.d.). Moreover, the test also includes an angiography to visualize arteries, veins, and other blood vessels. The overall purpose of the WADA test is to reduce the risk of post-surgical language and memory impairment while alleviating the deleterious effects of seizures.
Purpose of the WADA test
The WADA test is essentially a pre-surgical evaluation of the brain, which helps surgical teams determine which side of the brain is dominant for language capabilities and memory functions (Downstate Health Sciences University, n.d.). Moreover, the test also includes an angiography to visualize arteries, veins, and other blood vessels. The overall purpose of the WADA test is to reduce the risk of post-surgical language and memory impairment while alleviating the deleterious effects of seizures.
How does a WADA test work?
The WADA test is performed by a multidisciplinary team consisting of physicians and medical personnel. This specialized team can consist of neurologists, neuropsychologists, and neuroradiologists (Downstate Health Sciences University, n.d.). To begin, a catheter is inserted in the femoral artery, which is located in the groin area. The neuroradiologist carefully guides the catheter until it reaches the internal carotid artery (ICA) in the neck. Then, sodium amytal is injected, temporarily anesthetizing one side of the brain (Newton, 2022). Contralateral hemiparesis follows along with changes in brain activity, which is monitored by an electroencephalogram (EEG). The neuropsychologist administers several memory and language assessments and analyzes the outcomes (Downstate Health Sciences University, n.d.). Subsequently, the test is repeated on the other side with the same steps. After completing the evaluation, the results of the memory and language tests are compared to determine the best plan of surgical approach that can minimize the risk of memory and language impairments.
Before and After the Procedure
Before starting the pre-evaluation process, healthcare providers may begin preparing patients two weeks in advance, advising them to stop taking certain medications such as aspirin, nonsteroidal anti-inflammatory drugs (NSAIDs), and blood thinners (Cleveland Clinic, 2024). Additionally, before the WADA test, the healthcare professionals will assess your femoral and carotid artery by inserting a catheter. Some patients may experience a warm sensation, a little bit of pressure, and a metallic taste during the assessment. An angiogram and an encephalogram are also performed to look at blood flow and brain activity, respectively. Afterwards, the healthcare team will check a patient’s pulse, incisions, and any other health symptoms to confirm that he is recovering well (Cleveland Clinic, 2024). Moreover, some recommendations such as avoiding physical activities for up to 48 hours may be made. The WADA test is usually short, and patients are allowed to go home the same day.
Risks
There are a few controversies surrounding the risk and usage of the WADA test. For example, because the WADA test is an invasive procedure, there may be risks associated with it, although they are low (Cleveland Clinic, 2024). Any issues following the procedure may include seizures, encephalopathy, or stroke. People who may be at a slightly higher risk are those aged 65 or older, those with atherosclerosis, and those with a history of hypercholesterolemia. One study by Szantroch et al. (2019) assessed the adverse effects of the WADA test which was conducted using Propofol. The test was performed on 122 patients with temporal lobe epilepsy as part of the pre-evaluation group at the Department of Neurosurgery of the Medical University of Warsaw. The results showed that 61.4% of patients experienced some form of complications which ranged from carotid artery dissection, pseudoaneurysm at the puncture site, shivering, and seizures. Overall, the investigators concluded that the small risks may be negligible compared to the procedure’s ability to assess language and memory abilities in epileptic patients.
Conclusion
In conclusion, the WADA test is a valuable pre-surgical evaluation tool for patients with epilepsy or brain tumors. By determining the brain’s language and memory dominance, it helps surgeons plan procedures that minimize the risk of post-operative impairments. While the test carries some risks, including seizures, encephalopathy, and stroke, especially for older patients or those with underlying conditions, these risks are generally considered manageable compared to the benefits it provides. Overall, the WADA test ability to accurately assess brain function continues to make it a valuable asset in the management of neurological disorders.
References
Cleveland Clinic. (2024). Wada Test. Cleveland Clinic. Retrieved from: https://my.clevelandclinic.org/health/diagnostics/17628-wada-test
Downstate Health Sciences University. (n.d.). Wada test. https://www.downstate.edu/patient-care/find-treatment/treatment-centers/epilepsy-center/wada.html
Massot-Tarrús, A., White, K., & Mirsattari, S.M. (2019). Comparing the WADA test and functional MRI for the presurgical evaluation of memory in temporal lobe epilepsy. Current Neurology and Neuroscience Reports, 19(31). https://doi-org.usd.idm.oclc.org/10.1007/s11910-019-0945-8
Newton, H.B. (2022). Handbook of neuro-oncology neuroimaging. Academic Press. https://doi.org/10.1016/C2019-0-04194-5
Szantroch, M., Bala, A., Rysz, A., Zylkowski, J., & Marchel, A. (2019). Experience of adverse events with cerebral propofol testing in patients with drug resistant epilepsy. Scientific Reports, 9(592). https://doi.org/10.1038/s41598-018-36031-w
