Anosognosia during Wada testing.

Anosognosia, the verbally explicit denial of hemiplegia, is more often reported after right- than left-hemisphere lesions. However, this asymmetric incidence of anosognosia may be artifactual and related to the aphasia that often accompanies left-hemisphere lesions. Anosognosia has been attributed to psychological denial and the emotional changes associated with hemispheric dysfunction. Eight consecutive patients undergoing intracarotid barbiturate (methohexital) injections as part of their presurgical evaluations for intractable epilepsy were assessed for anosognosia after their hemiplegia and aphasia had cleared. After their left-hemisphere anesthesia, all subjects recalled both their motor and language deficits. However, after right-hemisphere anesthesia, none of the eight patients recalled their hemiplegia. These results suggest that anosognosia is more often associated with right- rather than left-hemisphere dysfunction and that it cannot be attributed to either psychological denial or the emotional changes associated with hemispheric dysfunction.     

Evaluation of adverse effects in intracarotid propofol injection for Wada test

The authors evaluated adverse effects of intracarotid propofol injection during a Wada test and their risk factors in 58 patients. Nineteen patients had an adverse effect, mostly in patients receiving more than 10 mg. For patients older than age 55 years or those requiring an injection dose greater than 20 mg to produce hemiplegia, propofol should be injected slowly and patients monitored for excitatory movements.     

The safety and efficacy of propofol as a replacement for amobarbital in intracarotid Wada testing of presurgical patients with epilepsy

ObjectiveThe intracarotid sodium amytal procedure (the “Wada test”) has for many years been the gold standard for language and memory lateralization and remains an important part of presurgical analysis for patients with medically intractable seizures. Due to shortages in the key sedative (amobarbital), neuropsychologists have turned to alternatives such as propofol. Our aim was to investigate the safety and efficacy of propofol relative to amobarbital in the Wada test.MethodsWe performed a retrospective review of the 97 Wada procedures performed at University of Iowa Hospitals and Clinics from 2007 through mid-2015.ResultsPropofol produced similar lateralization rates as amobarbital for both language and memory. Similar rates of patients in each group went on to have the resection surgery. With regard to safety, there were no differences found in average rate or severity of adverse effects. None of the demographic characteristics reviewed were predictive of increased risk for either drug.SignificanceThese findings support previous studies indicating that propofol is as safe and efficacious as amobarbital, and can continue to be used in Wada procedures with confidence.     

A comparison of propofol and amobarbital for use in the Wada test

129 Wada procedures were reviewed to examine the suitability of propofol (n=54) as a replacement to amobarbital (n=75) for use as an anaesthetic in the Wada test. Suitability was considered with respect to length of hemiplegia induced, the frequency of side effects and patient memory scores. Data was retrospectively collected from records of patients who had undergone the Wada procedure between 2004 and 2009 in Beaumont Hospital, Dublin. No significant differences were found between the two drugs on any of the measures. The results suggest that propofol represents a suitable alternative to amobarbital for use in the Wada procedure.     

Prediction of false-positive recognition errors during Wada testing

False-positive (FP) errors during recognition memory testing often interfere with interpretation of Wada test results. This study examined which clinical and neuropsychological variables provide the best prediction of these errors. Fifty-six patients completed the Wada test and the California Verbal Learning Test (CVLT). Subjects with three or more FP errors on the recognition trials of the CVLT were nearly twice as likely to exhibit FP responding during the Wada test. Further analysis indicates that FP errors during the Wada test appear to be the primary result of a stable and liberal response-bias rather than a result of any other neurological or procedure-related factor.     

不同剂量丙泊酚颈内动脉注射进行Wada试验的效果对比

目的探讨不同剂量的丙泊酚颈内动脉注射对语言及记忆功能优势半球测试的影响,对比不良反应的发生情况。方法对40例难治性癫痫患者采用颈内动脉注射丙泊酚进行Wada试验,根据所采用剂量不同分为10 mg和7 mg两组。对比两组不同剂量颈内动脉注射组的语言、记忆功能测试情况,计算注药后半球失活的持续时间,并观察不良反应的发生情况。同时收集患者的年龄、病程、全量表智商等相关数据,分析两不同剂量组的差异。结果所有患者均完成了语言优势半球测试,28例患者完成了记忆优势半球的测试。两组在年龄、病程、全量表智商方面的差异无统计学意义(均P0.05);注药后左侧半球和右侧半球的失活时间,两组之间的差异均无统计学意义(均P0.05)。两组患者记忆优势半球的测试成功率分别为56%和93%,差异有统计学意义(P=0.03)。两组均有发生Ⅰ、Ⅱ级的不良反应,但7 mg组未出现Ⅲ级不良反应,两组不良反应发生率的差异有统计学意义(P=0.01)。结论采用丙泊酚7 mg的剂量进行颈内动脉注射,可顺利完成语言优势半球的测试,提高记忆功能测试的成功率,减少不良反应的发生,是一个值得推荐的剂量。     

FMRI reveals functional cortex in a case of inconclusive Wada testing

OBJECTIVES: The intracarotid amobarbital test (Wada test) currently represents the gold standard for preoperative lateralization of hemispheric dominance. Here, we report an epileptic patient with a longstanding extended lesion of the left hemisphere showing absence of motor and speech dysfunction with left carotid amobarbital injection, but tetraplegia and speech arrest with right carotid injection interpreted as a neuroplastic shift of motor and language functions to the right hemisphere. In contrast to the Wada results, motor functional magnetic resonance imaging (fMRI) showed a strong left hemispheric activation with right hand movements. METHODS: Right and left hand motor fMRI was performed. FMRI results and neurophysiological information obtained by motor and sensory evoked potential measurements were compared with the Wada test results. RESULTS: Initial interpretation of neuroplastic shifts of intrinsic left hemisphere functions to the right brain was revised after fMRI results which were confirmed by motor and sensory evoked potentials. CONCLUSION: As motor inactivation usually is thought to be the most robust feature of the Wada test, this case demonstrates that fMRI may reveal residual functional cortex in cases of inconclusive Wada results.     

Wada testing and fMRI in a polyglot evaluated for epilepsy surgery

Despite advancements in the neurophysiology of language and presurgical evaluation for epilepsy surgery, there is a paucity of information in the literature regarding presurgical evaluation of multilingual patients. We present a case of a 52‐year‐old right‐handed woman with refractory epilepsy who was fluent in six languages and underwent subsequent trilingual presurgical evaluation which included neuropsychological testing, Wada testing, functional magnetic resonance imaging (fMRI), and electrocortical stimulation. These studies suggested a seizure focus in the left temporal lobe and language localization that was predominantly right‐hemispheric; she subsequently underwent left temporal laser interstitial thermal therapy without clinical disturbance in language function while remaining seizure‐free. A multidisciplinary effort was integral in providing an optimal outcome for this patient.     

Abnormal Wada and neuropsychological testing results due to topiramate therapy

A 46-year-old man experienced intractable seizures since childhood. Due to lack of response to antiepilepsy drugs (AEDs), he underwent a surgical evaluation that was consistent with seizure onset in the left medial temporal lobe. While on topiramate and carbamazepine, his preoperative neuropsychological scores and sodium amytal (Wada) scores were low and may have excluded him from surgery. Repeat testing on lamotrigine and carbamazepine showed improvement in his scores, allowing him to undergo surgery. Physicians must therefore be cautious in evaluating such test scores while a patient is on topiramate.     

Pediatric language mapping: sensitivity of neurostimulation and Wada testing in epilepsy surgery

PURPOSE: Functional mapping of eloquent cortex with electrical neurostimulation is used both intra- and extraoperatively to tailor resections. In pediatric patients, however, functional mapping studies frequently fail to localize language. Wada testing has also been reported to be less sensitive in children. METHODS: Thirty children (4.7 - 14.9 years) and 18 adult controls (18-59 years) who underwent extraoperative language mapping via implanted subdural electrodes at the NYU Comprehensive Epilepsy Center were included in the study. Ten children and 14 adults underwent preoperative Wada testing. Success of the procedures was defined as the identification of at least one language site by neurostimulation mapping and determination of hemispheric language dominance on the Wada test. RESULTS: In children younger than 10.2 years, cortical stimulation identified language cortex at a lower rate than was seen in children older than 10.2 years and in adults (p<0.05). This threshold, demonstrated by survival and chi2 analysis, was sharply defined in our data set. Additionally, Wada testing was more likely to be successful than was extraoperative mapping in this younger age group (p<0.05). CONCLUSIONS: Analysis of our series demonstrates that language cortex is less likely to be identified in children younger than 10 years, suggesting that alternatives to the current methods of cortical electrical stimulation, particularly the use of preoperative language lateralization, may be required in this age group.     

Wada testing reveals frontal lateralization for the memorization of words and faces.

Neuroimaging studies have suggested that specific regions of the frontal and medial temporal cortex are engaged during memory formation. Further, there is specialization across these regions such that verbal materials appear to preferentially engage the left regions while nonverbal materials primarily engage the right regions. An open question, however, has been to what extent frontal regions contribute to successful memory formation. The present study investigates this question using a reversible lesion technique known as the Wada test. Patients memorized words and unfamiliar faces while portions of their left and right hemispheres were temporarily anesthetized with sodium amytal. Subsequent memory tests revealed that faces were remembered better than words following left-hemisphere anesthesia, whereas words were remembered better than faces following right-hemisphere anesthesia. Importantly, inspection of the circulation affected by the amytal further suggests that these memory impairments did not result from direct anesthetization of the medial temporal regions. Taken in the context of the imaging findings, these results suggest that frontal regions may also contribute to memory formation in normal performance.     

Handedness, footedness, and language laterality: evidence from Wada testing

A total of 37 candidates for temporal lobe resection for epilepsy completed the Lateral Dominance Examination, a self-report instrument that measures hand and foot preference. Questionnaire results were compared with speech dominance, which had been determined by Intracarotid Sodium Amytal Procedure. Footedness was as good as handedness as a predictor of language laterality.     

Endovascular ablation of a temporal lobe epileptogenic focus - a complication of Wada testing

The authors report on a patient with a long history of medically refractory temporal lobe epilepsy. During pre-operative evaluation for anterior temporal lobectomy he underwent a Wada test for speech and memory lateralization. During the procedure, he suffered a focal cerebral infarct, within the right medial temporal lobe, at the site of the epileptic focus. This resulted in the resolution of his seizure disorder. The possibility of endovascular management of seizure disorders of the temporal lobe should be investigated further as a potentially minimal invasive therapeutic option for medically intractable epilepsy.     

Ambiguous Language in Wada Evaluations

Summary:  A case is presented with ambiguous cerebral language lateralization, as determined by the intracarotid amobarbital test. Reasons for ambiguous language findings for this test are discussed.     

Stimulus type affects Wada memory performance

The effects of amytal injection side, seizure focus laterality, and stimulus type (real and line-drawn objects, printed words, and faces) on recognition memory were studied during the Wada procedure. To-be-remembered stimuli were presented during cerebral anesthesia to 35 patients with left temporal lobe epilepsy (LTLE) and 28 patients with right temporal lobe epilepsy (RTLE), all with left hemisphere language dominance. In both groups, recognition of real and line-drawn objects was best after anesthetization of the lesional hemisphere. Recognition of faces was poor after either injection in patients with RTLE, but only after right injection in patients with LTLE. Conversely, recognition of words by patients with LTLE was impaired equally after either injection, but more so after left than right injection in patients with RTLE. The findings suggest that (1) real and line-drawn objects are "dually encoded" and memory accuracy depends on seizure focus laterality, and (2) accuracy in recognition of words and faces is related to seizure focus laterality, but may also depend on the language dominance of the hemisphere being assessed.