Transient shivering during Wada test provides insight into human thermoregulation

Revisiting intra-arterial drug delivery for treating brain diseases or is it "déjà-vu, all over again"?

For over six decades intra-arterial (IA) drugs have been sporadically used for the treatment of lethal brain diseases. In recent years considerable advance has been made in the IA treatment of retinoblastomas, liver and locally invasive breast cancers, but relatively little progress has been made in the treatment of brain cancers. High resting blood flow and the presence of the blood-brain barrier (BBB), makes IA delivery to the brain tissue far more challenging, compared to other organs. The lack of advance in the field is also partly due to the inability to understand the complex pharmacokinetics of IA drugs as it is difficult to track drug concentrations in sub-second time frame by conventional chemical methods. The advances in optical imaging now provide unprecedented insights into the pharmacokinetics of IA drug and optical tracer delivery. Novel delivery methods, improved IA drug formulations, and optical pharmacokinetics, present us with untested paradigms in pharmacology that could lead to new therapeutic interventions for brain cancers and stroke. The object of this review is to bring into focus the current practice, problems, and the potential of IA drug delivery for treating brain diseases. A concerted effort is needed at basic sciences (pharmacology and drug imaging), and translational (drug delivery techniques and protocol development) levels by the interventional neuroradiology community to advance the field.

Clinical significance and developmental changes of auditory-language-related gamma activity

OBJECTIVE

We determined the clinical impact and developmental changes of auditory-language-related augmentation of gamma activity at 50-120 Hz recorded on electrocorticography (ECoG).

METHODS

We analyzed data from 77 epileptic patients ranging 4-56 years in age. We determined the effects of seizure-onset zone, electrode location, and patient-age upon gamma-augmentation elicited by an auditory-naming task.

RESULTS

Gamma-augmentation was less frequently elicited within seizure-onset sites compared to other sites. Regardless of age, gamma-augmentation most often involved the 80-100 Hz frequency band. Gamma-augmentation initially involved bilateral superior-temporal regions, followed by left-side dominant involvement in the middle-temporal, medial-temporal, inferior-frontal, dorsolateral-premotor, and medial-frontal regions and concluded with bilateral inferior-Rolandic involvement. Compared to younger patients, those older than 10 years had a larger proportion of left dorsolateral-premotor and right inferior-frontal sites showing gamma-augmentation. The incidence of a post-operative language deficit requiring speech therapy was predicted by the number of resected sites with gamma-augmentation in the superior-temporal, inferior-frontal, dorsolateral-premotor, and inferior-Rolandic regions of the left hemisphere assumed to contain essential language function (r(2) = 0.59; p = 0.001; odds ratio = 6.04 [95% confidence-interval: 2.26-16.15]).

CONCLUSIONS

Auditory-language-related gamma-augmentation can provide additional information useful to localize the primary language areas.

SIGNIFICANCE

These results derived from a large sample of patients support the utility of auditory-language-related gamma-augmentation in presurgical evaluation.

Multimodality language mapping in patients with left-hemispheric language dominance on Wada test

OBJECTIVE

We determined the utility of electrocorticography (ECoG) and stimulation for detecting language-related sites in patients with left-hemispheric language-dominance on Wada test.

METHODS

We studied 13 epileptic patients who underwent language mapping using event-related gamma-oscillations on ECoG and stimulation via subdural electrodes. Sites showing significant gamma-augmentation during an auditory-naming task were defined as language-related ECoG sites. Sites at which stimulation resulted in auditory perceptual changes, failure to verbalize a correct answer, or sensorimotor symptoms involving the mouth were defined as language-related stimulation sites. We determined how frequently these methods revealed language-related sites in the superior-temporal, inferior-frontal, dorsolateral-premotor, and inferior-Rolandic regions.

RESULTS

Language-related sites in the superior-temporal and inferior-frontal gyri were detected by ECoG more frequently than stimulation (p < 0.05), while those in the dorsolateral-premotor and inferior-Rolandic regions were detected by both methods equally. Stimulation of language-related ECoG sites, compared to the others, more frequently elicited language symptoms (p < 0.00001). One patient developed dysphasia requiring in-patient speech therapy following resection of the dorsolateral-premotor and inferior-Rolandic regions containing language-related ECoG sites not otherwise detected by stimulation.

CONCLUSIONS

Language-related gamma-oscillations may serve as an alternative biomarker of underlying language function in patients with left-hemispheric language-dominance.

SIGNIFICANCE

Measurement of language-related gamma-oscillations is warranted in presurgical evaluation of epileptic patients.

The contribution of posterior circulation to memory function during the intracarotid amobarbital procedure

The purpose of this study was to evaluate the contribution of posterior circulation to memory function by comparing memory scores between patients with and without a foetal-type posterior cerebral artery (FTP) during the intracarotid amobarbital procedure (IAP) in epilepsy patients. Patients undergoing bilateral IAP between January 2004 and January 2010 were retrospectively included. Pre-test angiograms were assessed for the presence of a FTP. Memory function scores (% correct) after right and left injections were obtained. Functional significance of FTP was affirmed by relative occipital versus parietal EEG slow-wave increase during IAP. Memory and EEG scores were compared between patients with and without FTP (Mann-Whitney U test). A total of 106 patients were included, 73 with posterior cerebral arteries (PCA) without FTP ('non-FTP'), 28 patients with unilateral FTP and 5 with a bilateral FTP. Memory scores were lower when amytal was injected to the hemisphere contralateral to the presumed seizure focus (on the right decreasing from 98.3 to 59.1, and on the left decreasing from 89.1 to 72.4; p < 0.001). When IAP was performed on the side of FTP memory scores were significantly lower (70.8) compared to non-FTP (82.0; p = 0.02). Relative occipital EEG changes were 0.44 for FTP cases and 0.36 for non-FTP patients (p = 0.01). A relationship between vasculature and brain function was demonstrated by lower memory scores and more slow-wave activity on occipital EEG during IAP in patients with foetal-type PCA compared to patients with non-FTP. This suggests an important contribution of brain areas supplied by the PCA to memory function.