The test is usually performed prior to ablative surgery for epilepsy and sometimes prior to tumor resection. The aim is to determine which side of the brain is responsible for certain vital cognitive functions, namely speech and memory. The risk of post-operative cognitive change can be estimated, and depending on the surgical approach employed at the epilepsy surgery center, the need for awake craniotomies can be determined as well. The<unk>  has several side-effects. Drastic personality changes are rarely noted, but disinhibition is common. Also, contralateral hemiplegia, hemineglect and shivering are often seen. During one injection, typically the left hemisphere, the patient experiences impaired speech and language or is completely unable to express or understand language. Though the patient may not be able to talk, sometimes their ability to sing is preserved. This is because music and singing uses a different part of the brain than speech and language. Recovery from the anesthesia is rapid, and EEG recordings and distal grip strength may be used to determine when the medication has worn off. Generally, recovery of speech is dysphasic (contains errors in speech or comprehension) after a language dominant hemisphere injection. Though generally considered a safe procedure, there are at least minimal risks associated with the angiography procedure that guides the catheter to the internal carotid artery, perhaps related to the physician's experience. Researchers are looking into non-invasive ways to determine language and memory laterality—such as fMRI, TMS, magnetoencephalography, and near-infrared spectroscopy.
Wada test
Ishihara test
Weber test
Czermak–Hering test
Conconi test
Heidelberg test
Elek's test
Nardi test