Complete Corpus Callosotomy Brings Worthwhile Seizure Reduction in Both Pediatric and Adult Patients.

BACKGROUND AND OBJECTIVES: The influence of the age at which complete corpus callosotomy (CC) surgery is performed on seizure outcomes remains unclear. This study aimed to evaluate the age-dependent aspects of long-term seizure outcomes after complete CC. METHODS: We reviewed 41 patients who underwent one-stage complete CC. Seizure outcomes were analyzed for age at epilepsy onset and at complete CC, focal MRI abnormality, and etiology. RESULTS: The median age was 7 months at epilepsy onset and 93 months at complete CC. The median follow-up duration was 67 months. Sixteen patients had focal MRI lesions and 4 had only general atrophy. Etiology was identified in 20 patients. For overall seizure outcomes (N = 41), complete seizure freedom was achieved in 5 patients, excellent seizure reduction (>80%) in 11, good (50%-80%) in 5, and poor (<50%) in 20. Freedom was correlated with younger age at complete CC and unknown etiology (P ≤ .05). Freedom was only achieved in patients aged younger than 7 years. Worthwhile (≥50%, freedom, excellent, and good) and not worthwhile (<50%, poor) overall seizure reduction showed no statistical difference in age at complete CC. No related factor was found for worthwhile overall seizure reduction. For drop attack outcomes (N = 31), freedom was achieved in 22 cases, excellent in 5, and poor in 4. Freedom was correlated with younger age at complete CC (P < .05) although freedom was achieved in 4 of 7 patients older than 20 years. Age at complete CC showed no statistical difference between worthwhile (≥50%) and not worthwhile (<50%) drop attack reduction. Worthwhile drop attack reduction was correlated with unknown etiology (P < .05). Complications were mild and transient. CONCLUSION: Complete CC is an excellent surgical option based on favorable seizure outcomes and acceptable complications in our present study.

Remission of startle epilepsy provoked by acoustic stimuli following complete callosotomy: A case study.

Herein, we present the case of a 21-year-old man with a history of generalized tonic seizures since the age of 4 years. These seizures occurred either spontaneously or could be provoked by auditory stimuli such as the sounds of a vacuum cleaner or an electric shaver. Despite trials with 10 different anti-seizure medications, his seizures remained refractory. Interictal electroencephalography (EEG) revealed generalized epileptiform activity, whereas ictal EEG showed a generalized attenuation pattern. Magnetic resonance imaging revealed extensive chronic infarctions, predominantly in the bilateral cerebral watershed areas. At the age of 17, the patient underwent a one-stage complete callosotomy, which only achieved remission of auditory-provoked seizures. Based on this experience and published reports, we propose that the posterior corpus callosum, particularly the isthmus and anterior splenium, may be involved in seizures caused by unexpected sound stimuli.

Super-selective injection of propofol into the intracranial arteries enables Patient's self-evaluation of expected neurological deficit.

INTRODUCTION: It is hard to realize the extent of the expected postoperative neurological deficit for patients themselves. The provision of appropriate information can contribute not only to examining surgical indications but also to filling the gap between patient and expert expectations. We hypothesized that propofol infusion into the intracranial arteries (ssWada) could induce focal neurological symptoms with preserved wakefulness, enabling the patients to evaluate the postsurgical risk subjectively. METHODS: Presurgical evaluation using ssWada was performed in 28 patients with drug-resistant epilepsy. Based on anatomical knowledge, propofol was super-selectively infused into the intracranial arteries including the M1, M2, and M3 segments of the middle cerebral artery (MCA), A2 segment of the anterior cerebral artery, and P2 segment of the posterior cerebral artery to evaluate the neurological and cognitive symptoms. We retrospectively analyzed a total of 107 infusion trials, including their target vessels, and elicited symptoms of motor weakness, sensory disturbance, language, unilateral hemispatial neglect (UHN), and hemianopsia. We evaluated preserved wakefulness which enabled subjective evaluations of the symptoms and comparison of the subjective experience to the objective findings, besides adverse effects during the procedure. RESULTS: Preserved wakefulness was found in 97.2% of all trials. Changes in neurological symptoms were positively evaluated for motor weakness in 51.4%, sensory disturbance in 5.6%, language in 48.6%, UHN in 22.4%, and hemianopsia in 32.7%. Six trials elicited seizures. Multivariate analysis showed significant correlations between symptom and infusion site of language and left side, language and MCA branches, motor weakness and A2 or M2 superior division, and hemianopsia and P2. Transient adverse effect was observed in 8 cases with 12 infusion trials (11.2 %). CONCLUSION: The ssWada could elicit focal neurological symptoms with preserved wakefulness. The methodology enables specific evaluation of risk for cortical resection and subjective evaluation of the expected outcome by the patients.

The grasp reflex in patients with idiopathic normal pressure hydrocephalus.

OBJECTIVE: To investigate the prevalence and intensity of grasp reflexes and to examine changes in these reflexes after shunt surgery in patients with idiopathic normal pressure hydrocephalus (iNPH). METHODS: We enrolled 147 patients with probable iNPH. A standard procedure was used to determine the presence of grasp reflexes, and the intensity of these reflexes was assessed using a four-category classification. Clinical rating scales and their correlation with grasp reflexes were also evaluated. Grasp reflexes were reassessed in 72 patients 1 year after surgery. RESULTS: We found that approximately 50.3% of patients with iNPH exhibited a positive grasp reflex. Among these patients, 69% exhibited bilateral positivity, while the remaining patients showed unilateral positivity. Furthermore, the intensity of the grasp reflex was significantly correlated with the severity of gait and with cognitive, urinary, motor, and behavioural symptoms. Surgical interventions led to a reduction (41.7%) or maintenance (30.6%) of the reflex intensity in 72.3% of iNPH patients. The changes in reflex intensity showed significant positive correlations with changes in the number of steps of the Timed Up and Go test and Trail Making Test-A scores but not with changes in total scores on the iNPH Grading Scale. CONCLUSION: This retrospective study identified grasp reflexes as a highly prevalent phenomenon in patients with iNPH. These reflexes can assist in evaluating the severity of various symptoms, including cognitive, gait, urinary, motor and emotional symptoms.

Distant recurrence in the cerebellar dentate nucleus through the dentato-rubro-thalamo-cortical pathway in supratentorial glioma cases.

BACKGROUND: Distant recurrence can occur by infiltration along white matter tracts or dissemination through the cerebrospinal fluid (CSF). This study aimed to clarify the clinical features and mechanisms of recurrence in the dentate nucleus (DN) in patients with supratentorial gliomas. Based on the review of our patients, we verified the hypothesis that distant DN recurrence from a supratentorial lesion occurs through the dentato-rubro-thalamo-cortical (DRTC) pathway. METHODS: A total of 380 patients with supratentorial astrocytoma, isocitrate dehydrogenase (IDH)-mutant (astrocytoma), oligodendroglioma, IDH mutant and 1p/19q-codeleted (oligodendroglioma), glioblastoma, IDH-wild type (GB), and thalamic diffuse midline glioma, H3 K27-altered (DMG), who underwent tumor resection at our department from 2009 to 2022 were included in this study. Recurrence patterns were reviewed. Additionally, clinical features and magnetic resonance imaging findings before treatment, at the appearance of an abnormal signal, and at further progression due to delayed diagnosis or after salvage treatment of cases with recurrence in the DN were reviewed. RESULTS: Of the 380 patients, 8 (2.1%) had first recurrence in the DN, 3 were asymptomatic when abnormal signals appeared, and 5 were diagnosed within one month after the onset of symptoms. Recurrence in the DN developed in 8 (7.4%) of 108 cases of astrocytoma, GB, or DMG at the frontal lobe or thalamus, whereas no other histological types or sites showed recurrence in the DN. At the time of the appearance of abnormal signals, a diffuse lesion developed at the hilus of the DN. The patterns of further progression showed that the lesions extended to the superior cerebellar peduncle, tectum, tegmentum, red nucleus, thalamus, and internal capsule along the DRTC pathway. CONCLUSION: Distant recurrence along the DRTC pathway is not rare in astrocytomas, GB, or DMG at the frontal lobe or thalamus. Recurrence in the DN developed as a result of the infiltration of tumor cells through the DRTC pathway, not dissemination through the CSF.

Assessment of language lateralization in epilepsy patients using the super-selective Wada test.

BACKGROUND: The classical Wada test (cWada), performed by injecting a short-acting anesthetic through the intracarotid route, helps determine language dominance. In the cWada, adverse effects are observed in 10-30% of trials, hindering accurate assessments. In this study, we assessed the effectiveness of the super-selective Wada test (ssWada), a more selective approach for anesthetic infusion into the middle cerebral artery (MCA). METHODS: We retrospectively examined the data of 17 patients with epilepsy who underwent ssWada via anesthetic injection into one M1 segment of the MCA and at least one contralateral trial. RESULTS: The ssWada identified 12 patients with left language dominance, 3 with right language dominance, and 2 with bilateral language distribution. Nine trials on the language dominant side resulted in global aphasia for patients with left- or right language dominance. Of the 13 trials conducted on the non-dominant language side, 12 revealed intact language function and one resulted in confusion. Among these, the outcomes of global aphasia or no language impairment were confirmed in the contralateral trials. Among the 22 trials of unilateral M1 injections in patients with unilateral language dominance, 21 (95.5%) showed either global aphasia or no language impairment, indicating language dominance. CONCLUSIONS: The ssWada yields clear results, with a high rate of over 90% in determining the language dominant hemisphere with few side effects.

Bilateral and asymmetrical localization of language function identified by the superselective infusion of propofol in an epilepsy patient with a mild malformation of cortical development: illustrative case.

BACKGROUND: Atypical localization of language function can result in unexpected postsurgical deficits after cortical resection, but it is difficult to predict the risk in the presurgical evaluation. The authors experienced a rare case of the bilateral and independent existence of different components of language function identified by segmented evaluation of anatomical anterior and posterior language areas using the superselective infusion of propofol. OBSERVATIONS: A 32-year-old right-handed female presented with drug-resistant epilepsy. Comprehensive epilepsy evaluation suggested that the epileptic foci involved the whole left frontal lobe but provided less evidence of structural abnormality. To estimate the extent of functional deterioration likely to be caused by an extended left frontal lobectomy, the authors evaluated segmented cortical function in the ipsi- and contralateral hemispheres by the superselective infusion of propofol into the branches of the intracranial artery. The results revealed bilateral and asymmetrical localization of language function because the patient presented with different components of aphasia in each hemisphere. Based on the authors' assessment of her functional tolerance, an extended left frontal lobectomy was performed and resulted in neurological deficits within the anticipated range. LESSONS: An accurate understanding of the correlations between vascular and functional anatomy and the highly specific evaluation of language function provides more advanced presurgical assessment, allowing more tailored planning of cortical resection.

Language MEG predicts postoperative verbal memory change in left mesial temporal lobe epilepsy.

OBJECTIVE: To clarify whether preoperative language magnetoencephalography (MEG) predicts postoperative verbal memory (VM) changes in left mesial temporal lobe epilepsy (LMTLE). METHODS: We reviewed 18 right-handed patients with LMTLE who underwent anterior temporal lobectomy or selective amygdala hippocampectomy, 12 with (HS+) and 6 without hippocampal sclerosis (HS-). Patients underwent neuropsychological assessment before and after surgery. MEG was measured with an auditory verbal learning task in patients preoperatively and in 15 right-handed controls. Dynamic statistical parametric mapping (dSPM) was used for source imaging of task-related activity. Language laterality index (LI) was calculated by z-score of dSPM in language-related regions. LI in the region of HS+ and HS- was compared to controls. The correlation between LI and postoperative VM change was assessed in HS+ and HS-. RESULTS: Preoperative LI in supramarginal gyrus showed greater right-shifted lateralization in both HS+ and HS- than in controls. Right-shifted LI in supramarginal gyrus was correlated with postoperative VM increase in HS+ (p = 0.019), but not in HS-. CONCLUSIONS: Right-shifted language lateralization in dSPM of MEG signals may predict favorable VM outcome in HS+ of LMTLE. SIGNIFICANCE: Findings warrant further investigation of the relation between regional language laterality index and postoperative verbal memory changes.

Visualization of the lenticulostriate arteries, long insular arteries, and long medullary arteries on intra-arterial computed tomography angiography with ultrahigh resolution in patients with glioma.

PURPOSE: The anatomical association between the lesion and the perforating arteries supplying the pyramidal tract in insulo-opercular glioma resection should be evaluated. This study reported a novel method combining the intra-arterial administration of contrast medium and ultrahigh-resolution computed tomography angiography (UHR-IA-CTA) for visualizing the lenticulostriate arteries (LSAs), long insular arteries (LIAs), and long medullary arteries (LMAs) that supply the pyramidal tract in two patients with insulo-opercular glioma. METHODS: This method was performed by introducing a catheter to the cervical segment of the internal carotid artery. The infusion rate was set at 3 mL/s for 3 s, and the delay time from injection to scanning was determined based on the time-to-peak on angiography. On 2- and 20-mm-thick UHR-IA-CTA slab images and fusion with magnetic resonance images, the anatomical associations between the perforating arteries and the tumor and pyramidal tract were evaluated. RESULTS: This novel method clearly showed the relationship between the perforators that supply the pyramidal tract and tumor. It showed that LIAs and LMAs were far from the lesion but that the proximal LSAs were involved in both cases. Based on these results, subtotal resection was achieved without complications caused by injury of perforators. CONCLUSION: UHR-IA-CTA can be used to visualize the LSAs, LIAs, and LMAs clearly and provide useful preoperative information for insulo-opercular glioma resection.

Randomized placebo-controlled trial of CL2020, an allogenic muse cell-based product, in subacute ischemic stroke.

Effective treatments for stroke after the acute phase remain elusive. Muse cells are endogenous, pluripotent, immune-privileged stem cells capable of selectively homing to damaged tissue after intravenous injection and replacing damaged/lost cells via differentiation. This randomized, double-blind, placebo-controlled trial enrolled ischemic stroke patients with modified Rankin Scale (mRS) ≥3. Randomized patients received a single intravenous injection of an allogenic Muse cell-based product, CL2020 (n = 25), or placebo (n = 10), without immunosuppressant, 14-28 days after stroke onset. Safety (primary endpoint: week 12) and efficacy (mRS, other stroke-specific measures) were assessed up to 52 weeks. Key efficacy endpoint was response rate (percentage of patients with mRS ≤2 at week 12). To week 12, 96% of patients in the CL2020 group experienced adverse events and 28% experienced adverse reactions (including one Grade 4 status epilepticus), compared with 100% and 10%, respectively, in the placebo group. Response rate was 40.0% (95% CI, 21.1-61.3) in the CL2020 group and 10.0% (0.3-44.5) in the placebo group; the lower CI in the CL2020 group exceeded the preset efficacy threshold (8.7% from registry data). This randomized placebo-controlled trial demonstrated CL2020 is a possible effective treatment for subacute ischemic stroke.Registry information: JAPIC Clinical Trials Information site (JapicCTI-184103, URL: https://www.clinicaltrials.jp/cti-user/trial/ShowDirect.jsp?japicId=JapicCTI-184103).

Referral odyssey plot to visualize causes of surgical delay in mesial temporal lobe epilepsy with hippocampal sclerosis.

The "odyssey plot" was used to visualize referral delays in epilepsy surgery. Participants were 36 patients (19 males; 13-67 years, median 27 years) with mesial temporal lobe epilepsy with hippocampal sclerosis (HS) who underwent resection surgery. The "referral odyssey plot" included five clinical episodes: seizure onset (T1), first visits to a non-epileptologist (T2) and to an epileptologist (T3), first admission to our epilepsy monitoring unit (EMU) (T4), and resection surgery (T5). For each patient, we identified the first seizure type: the physician who first diagnosed focal aware seizure (FAS), focal impaired awareness seizure (FIAS), focal to bilateral tonic-clonic seizure (FBTCS), and radiologically suspected HS. Within the overall delay (T1-T5, median 18 years; interquartile range [IQR] 14), non-epileptologist's delay (T2-T3, 11.5 years; IQR 12.25) was far (p < 0.0001) longer than patient's (T1-T2, 0 year; IQR 2.25), epileptologist's (T3-T4, 1 year; IQR 4), or after-EMU delay (T4-T5, 1 year; IQR 1). FAS onset cases had significantly longer T1-T2 (N = 5, median 7 years; IQR 6) than FIAS (N = 22, 0 year; IQR 1, p < 0.005) or FBTCS onset cases (N = 9, 0 year; IQR 0, p < 0.001). FAS was correctly diagnosed first by non-epileptologists in 17.9%, by out-patient epileptologists in 35.7%, and at the EMU in 46.4%. FIAS was correctly diagnosed first by non-epileptologists in 94.4% and by out-patient epileptologists in 5.6%. Non-epileptologists diagnosed FBTCS in all cases. HS was diagnosed by non-epileptologists in 13.9%, by out-patient epileptologists in 47.2%, and at the EMU in 38.9%. Early referral to epileptologists is most critical for early surgery. Early utilization of the EMU is highly recommended because FAS is often overlooked by outpatient epileptologists. The odyssey plot will be useful to improve the healthcare system for other types of epilepsy.

Causal involvement of medial inferior frontal gyrus of non-dominant hemisphere in higher order auditory perception: A single case study.

The medial side of the operculum is invisible from the lateral surface of cerebral cortex, and its functions remain largely unexplored using direct evidence. Non-invasive and invasive studies have proved functions on peri-sylvian area including the inferior frontal gyrus (IFG) and superior temporal gyrus within the language-dominant hemisphere for semantic processing during verbal communication. However, within the non-dominant hemisphere, there was less evidence of its functions except for pitch or prosody processing. Here we add direct evidence for the functions of the non-dominant hemisphere, the causal involvement of the medial IFG for subjective auditory perception, which is affected by the context of the condition, regarded as a contribution in higher order auditory perception. The phenomenon was clearly distinguished from absolute and invariant pitch perception which is regarded as lower order auditory perception. Electrical stimulation of the medial surface of pars triangularis of IFG in non-dominant hemisphere via depth electrode in an epilepsy patient rapidly and reproducibly elicited perception of pitch changes of auditory input. Pitches were perceived as either higher or lower than those given without stimulation and there was no selectivity for sound type. The patient perceived sounds as higher when she had greater control over the situation when her eyes were open and there were self-cues, and as lower when her eyes were closed and there were investigator-cues. Time-frequency analysis of electrocorticography signals during auditory naming demonstrated medial IFG activation, characterized by low-gamma band augmentation during her own vocal response. The overall evidence provides a neural substrate for altered perception of other vocal tones according to the condition context.

Olfactory Dysfunction, an Often Neglected Symptom of Hydrocephalus: Experience from a Case of Late-Onset Idiopathic Aqueductal Stenosis.

Disturbance of smell is often accompanied with common neurodegenerative diseases such as Parkinson's and Alzheimer's diseases. In addition, patients with head trauma, intracranial tumors, and hydrocephalus can also develop olfactory dysfunction, and some of which can improve with treatment of the underlying disease. In clinical practice, few patients complain of smell disturbances, thus olfactory dysfunction is often overshadowed by visible motor symptoms. Herein, we report a case of late-onset idiopathic aqueductal stenosis, a rare form of adult-onset hydrocephalus in which olfactory dysfunction and gait disturbance was markedly improved after endoscopic ventriculostomy. This case report is expected to make more physicians aware that hydrocephalus can cause olfactory dysfunction and that it can be corrected postoperatively. Furthermore, in addition to motor and neuropsychological function, olfactory function test might be useful for functional assessment before and after surgical treatment of hydrocephalus.

Interhemispheric asymmetrical change in gray matter volume in patients with unilateral hippocampal sclerosis.

Objectives: To clarify the interhemispheric asymmetrical change in gray matter volume (GMV) in unilateral hippocampal sclerosis (HS), we compared changes in GMV relative to normal subjects between the HS and contralateral or non-HS sides. Material and Methods: Forty-five patients with unilateral HS and 30 healthy subjects were enrolled. We quantified changes in GMV in the patients with HS as compared to GMV in the normal subjects by introducing the Z-score (Z-GMV) in each region or region of interest in unilateral HS. Then, we assessed the asymmetrically decreased regions, that is, regions with significantly higher Z-GMV on the HS side than the contralateral or non-HS side. Z-GMV was calculated according to the two templates of 58 regions per hemisphere covering the whole brain by anatomical automatic labeling (AAL) and 78 regions per cerebral hemisphere using the Anatomy Toolbox. Results: Seven and four regions in AAL and 17 and 11 regions in Anatomy Toolbox were asymmetrically decreased in the Left Hand Side (LHS) and Right Hand Side (RHS), respectively. Hippocampus and Caudate in AAL, five subregions of the hippocampus (CA1-3, Dentate Gyrus and hippocampus-amygdala-transition-area and 4 extrahippocampal regions including two subregions in amygdala (CM: Centromedial, SF: Superficial), basal forebrain (BF) (Ch4), and thalamus (temporal) in anatomy toolbox were common among LHS and RHS concerning asymmetrically decreased regions. Conclusion: By introducing Z-GMV, we demonstrated the regions with asymmetrically decreased GMV in LHS and RHS, and found that the hippocampus and extrahippocampal regions, including the BF, were the common asymmetrically decreased regions among LHS and RHS.

Distribution of postictal slowing has an additional yield to interictal epileptiform discharge in predicting surgical outcomes in temporal lobe epilepsy.

OBJECTIVE: To investigate whether the slowing of bilateral postictal scalp electroencephalography (EEG) after focal impaired awareness seizures is associated with poor seizure outcomes after temporal lobe epilepsy (TLE) surgery. METHODS: This retrospective cohort study was conducted in the Department of Epileptology, Tohoku University Hospital from 2010 to 2020. The study included 42 patients with TLE who underwent a detailed presurgical evaluation and sequential resective surgery for the unilateral probable epileptogenic temporal lobe with 1 year or more of follow-up. We reviewed the interictal epileptiform distribution and those of the ictal and postictal epochs of the first focal impaired awareness seizure recorded in presurgical scalp EEG. We classified patients either with postoperative seizure-free status (Engel I) as group A or those with seizure persistence (Engel II-IV) as group B. RESULTS: Of 42 patients, 29 (69%) were classified into group A. Compared with group B, group A had a lower number of bilateral postictal polymorphic delta activity (PPDA) (10.3%: 61.5%) and bilateral interictal epileptiform discharges (IEDs) (13.8%: 69.2%) (P = 0.003, P = 0.001, respectively). A combined analysis of bilateral PPDA and IEDs per individual patient showed significantly more frequent seizure persistence after surgery (P < 0.0001) than a single analysis of bilateral IEDs or PPDA alone (P = 0.001). The regression analysis revealed that bilaterally distributed PPDA or IEDs had 13.50 or 13.72 times higher odds of persisting seizures within 1 year of surgery (95% confidence interval: 1.90-95.88; 2.12-88.87, respectively) (P = 0.009, 0.006). SIGNIFICANCE: The results of this study revealed that the bilateral distribution of PPDA was associated with poor postoperative seizure outcomes in patients with TLE, as well as bilateral IEDs. Additionally, the concomitant bilateral distribution of interictal and postictal changes is a strong indicator of poor surgical outcomes.

Totally Organic Hydrogel-Based Self-Closing Cuff Electrode for Vagus Nerve Stimulation.

An intrinsically soft organic electrode consisting of poly(3,4-ethylenedioxythiophene)-modified polyurethane (PEDOT-PU) is embedded into a bilayer film of polyvinyl alcohol (PVA) hydrogels for developing a self-closing cuff electrode for neuromodulation. The curled form of the PVA hydrogel is prepared by releasing internal stress in the bilayer structure. The inner diameter of the cuff electrode is set to less than 2 mm for immobilization to the vagus nerve (VN) of humans and pigs. The stability of the immobilization is examined, while the pressure applied to a nerve bundle is at a harmless level (≈200 Pa). Since the electrode is totally organic, MRI measurements can be conducted without image artifacts. The large electric capacitance of the PEDOT-PU (≈27 mF cm-2 ) ensures a safe stimulation of living tissues without Faradaic reactions. The practical performance of the cuff electrode for VN stimulation is demonstrated by observation of bradycardia induction in a pig.

Determination of language areas in patients with epilepsy using the super-selective Wada test.

The Wada test is the gold standard for determining language-dominant hemisphere. However, the precise determination of language areas in each patient requires more invasive methods, such as electrocortical stimulation. Some studies have reported the use of anesthetic injection into selective cerebral arteries to predict postoperative function. To assess the function of the anterior and posterior language areas separately, we developed an advanced test named the "super-selective Wada test" (ssWada). The ssWada procedure is as follows: an endovascular neurosurgeon identifies the arterial branches of the middle cerebral artery (MCA) perfusing the anterior language area of the inferior frontal gyrus and the posterior language area of the posterior part of the superior temporal gyrus using angiography. Behavioral neurologists assess language symptoms before and after propofol administration using a microcatheter tip in the selected arterial branch. From 30 serial patients with epilepsy who underwent ssWada test at Tohoku University Hospital, we retrospectively reviewed patients in whom multiple areas in the bilateral MCA region was examined. Eight cases were identified in this study. All eight cases had been considered for resection of the area overlapping the classical language area. Three of the eight cases were left-dominant, and the within-hemisphere distribution was also considered typical. One case was determined to be left-dominant but atypical in the intra-hemispheric functional distribution. Two cases were right-dominant, and the intra-hemispheric functional distribution was considered a mirror image of the typical pattern. The remaining two cases were considered atypical, not only in terms of bilateral language function, but also in terms of anterior-posterior functional distribution. This case series demonstrates the potential utility of ssWada in revealing separate function of the anterior and posterior language areas. The ssWada allows simulation of local surgical brain resection and detailed investigation of language function, which potentially contributes to planning the resection area. Although indications for ssWada are quite limited, it could play a complementary role to noninvasive testing because it provides information related to resection using a different approach.

Methodological assessment of the reduction of dissemination risk and quantification of debris dispersion during dissection with a surgical aspirator.

OBJECTIVE: We developed an actuator-driven pulsed water jet (ADPJ) device to achieve maximal lesion dissection with minimal risk of normal structural damage. Despite the unique dissection characteristics, there is a risk of dissemination of tissue dispersion; however, there is no established method to quantify the dispersion. Hence, this study aimed to assess the factors associated with dispersion and propose a simple experimental method using spectrophotometry to evaluate the degree of dispersion in a wet field. RESULTS: Methylene blue-stained brain phantom gelatin was immersed in a chamber with distilled water solution and dissected with an ADPJ. The dispersed gelatin solution was stirred and warmed to dissolve. The absorbance of the solution was measured spectrophotometrically. First, a reference standard curve was constructed to confirm the relationship between the absorbance and the amount of the dispersed gelatin. A clear proportional correlation was observed, which indicated that absorbance measurements can help evaluate the amount of dispersion. Using this method, we revealed that a high dissection force, insufficient suction, and inappropriate long distance between the nozzle tip and the target were associated with increased dispersion. This method might constitute a versatile and reliable approach to evaluate dispersion and aid in the development of surgical devices.