Experience on the use of Vagus Nerve Stimulation during pregnancy

OBJECTIVE

Vagus Nerve Stimulation (VNS) is a neuromodulation device approved for the treatment of medically refractory epilepsy. Worldwide, only 35 cases of pregnancies that has been described. This study aims to continue to increase the limited knowledge of the use of VNS during pregnancy.

METHODS

We interrogated the database of the Epilepsy program at Western University (1998-2018), and identified those patients who were implanted with VNS and became pregnant.

RESULTS

From 114 patients implanted with VNS in our centre, four patients had a total of seven pregnancies. This is the first report with one woman implanted with VNS having three pregnancies. Three patients had genetic generalized epilepsy and one focal epilepsy due to periventricular nodular heterotopia. The median duration since implantation was 3.17 years (IQR: 1.33-4.33) and the output was 2.75 mA (IQR: 1.5-3.5). No modifications in stimulation settings were made in any patient during pregnancy. Three patients had obstetric complications, requiring c-sections. All babies were healthy, except one with intellectual disabilities of unclear severity.

CONCLUSION

Our small sample suggests VNS could increase the obstetrical complications, but is likely safe for the fetus. However, a larger sample size should be collected to determine safety and potential teratogenicity of VNS.

The CanPain SCI Clinical Practice Guidelines for Rehabilitation Management of Neuropathic Pain after Spinal Cord: introduction, methodology and recommendation overview

STUDY DESIGN

Clinical practice guidelines.

OBJECTIVES

The objective was to develop the first Canadian clinical practice guidelines for the management of neuropathic pain in people with spinal cord injury (SCI).

SETTING

The guidelines are relevant for inpatient and outpatient SCI rehabilitation settings in Canada.

METHODS

The guidelines were developed in accordance with the Appraisal of Guidelines for Research and Evaluation II tool. A Steering Committee and Working Group reviewed the relevant evidence on neuropathic pain management (encompassing screening and diagnosis, treatment and models of care) after SCI. The quality of evidence was scored using Grading of Recommendations Assessment, Development and Evaluation (GRADE). A consensus process was followed to achieve agreement on recommendations and clinical considerations.

RESULTS

The Working Group developed 12 recommendations for screening and diagnosis, 12 recommendations for treatment and 5 recommendations for models of care. Important clinical considerations accompany each recommendation.

CONCLUSIONS

The Working Group recommendations for the management of neuropathic pain after SCI should be used to inform practice.

Fusion and visualization of intraoperative cortical images with preoperative models for epilepsy surgical planning and guidance

OBJECTIVE

During epilepsy surgery it is important for the surgeon to correlate the preoperative cortical morphology (from preoperative images) with the intraoperative environment. Augmented Reality (AR) provides a solution for combining the real environment with virtual models. However, AR usually requires the use of specialized displays, and its effectiveness in the surgery still needs to be evaluated. The objective of this research was to develop an alternative approach to provide enhanced visualization by fusing a direct (photographic) view of the surgical field with the 3D patient model during image guided epilepsy surgery.

MATERIALS AND METHODS

We correlated the preoperative plan with the intraoperative surgical scene, first by a manual landmark-based registration and then by an intensity-based perspective 3D-2D registration for camera pose estimation. The 2D photographic image was then texture-mapped onto the 3D preoperative model using the solved camera pose. In the proposed method, we employ direct volume rendering to obtain a perspective view of the brain image using GPU-accelerated ray-casting. The algorithm was validated by a phantom study and also in the clinical environment with a neuronavigation system.

RESULTS

In the phantom experiment, the 3D Mean Registration Error (MRE) was 2.43 ± 0.32 mm with a success rate of 100%. In the clinical experiment, the 3D MRE was 5.15 ± 0.49 mm with 2D in-plane error of 3.30 ± 1.41 mm. A clinical application of our fusion method for enhanced and augmented visualization for integrated image and functional guidance during neurosurgery is also presented.

CONCLUSIONS

This paper presents an alternative approach to a sophisticated AR environment for assisting in epilepsy surgery, whereby a real intraoperative scene is mapped onto the surface model of the brain. In contrast to the AR approach, this method needs no specialized display equipment. Moreover, it requires minimal changes to existing systems and workflow, and is therefore well suited to the OR environment. In the phantom and in vivo clinical experiments, we demonstrate that the fusion method can achieve a level of accuracy sufficient for the requirements of epilepsy surgery.

Cortical reorganization following anterior temporal lobectomy in patients with temporal lobe epilepsy

BACKGROUND

Functional MRI was used to study the impact of temporal lobe epilepsy (TLE) and anterior temporal lobectomy (ATL) on the cortical language network in patients with medically refractory TLE.

METHODS

Nineteen patients with medically refractory TLE and 11 healthy control subjects were enrolled in this study. Ten patients underwent left ATL (mean age 35.2 +/- 3.8 years), and 9 underwent right ATL (mean age 35.9 +/- 2.6 years). The subjects silently generated verbs in response to a series of visually presented nouns inside the scanner. Correlation analysis was performed between the subjects' performance on the clinical language tests and their neural response in the a priori cortical regions.

RESULTS

Preoperative data revealed that the patients with TLE showed increased neural activity in the right inferior frontal gyri (IFG) and middle frontal gyri (MFG). The right TLE patients demonstrated strong correlation between their language performance and the level of cortical activation within the typical language areas. However, such a correlation was absent in the left TLE patients. After the ATL surgery, the left TLE patients showed reduced activation in the left MFG and right IFG, whereas no difference was observed in the right TLE patients. In the right TLE patients, the correlation between language performance and neural response shifted from the typical language areas to the anterior cingulate cortex.

CONCLUSION

This study demonstrates that the cortical language network is affected differently by the left and right temporal lobe epilepsy and is reorganized after anterior temporal lobectomy.

Endoscopically guided fenestration of the choroidal fissure for treatment of trapped temporal horn

In recent years endoscopic procedures have been used more frequently to treat loculated hydrocephalus. The trapped temporal horn, a specific type of loculation, has traditionally been treated by means of ventricular shunt placement. By opening up loculations, however, this procedure can be simplified or, in some cases, even avoided. In this report the author discusses a case of trapped temporal horn that was caused by fungal meningitis and treated using endoscopically guided fenestration of the choroidal fissure, leading to clinical and radiographic resolution of the syndrome. Using this simple procedure allows the surgeon to take advantage of normal temporal horn anatomy and landmarks, avoiding the scarred and distorted region of ventricular obstruction.

Stereotactic surgery for temporal lobe epilepsy

In light of the recent resurgence of interest in stereotactic functional procedures, the authors have reviewed the role of stereotactic ablative surgery in the treatment of temporal lobe epilepsy. Literature pertaining to stereotactic amygdalotomy, hippocampotomy and fornicotomy is reviewed and summarized. However, the results presented in those early studies are difficult to interpret given the surgical techniques and outcome assessment used. Modern stereotactic ablative surgery using current image-guided technology offers the opportunity to revisit some of these techniques. In recent studies of stereotactic amygdalohippocampotomy, outcomes are not as favorable as those obtained with standard temporal resections. However, these relatively discrete ablative techniques may shed light on the anatomical substrate underlying temporal lobe epilepsy.

Cognitive outcome following pallidotomy: the influence of side of surgery and age of patient at disease onset

OBJECT

The authors studied the neuropsychological correlates of stereotactically guided lesioning of the right and left posteroventral globus pallidus internus (GPi) in a prospective series of patients suffering from Parkinson's disease (PD).

METHODS

Eighteen patients with PD who underwent stereotactically guided lesioning of the GPi (left side in 10 patients and right side in eight) completed neuropsychological evaluations before and after surgery. Patients served as their own controls. Multiple two-by-two repeated-measures analyses of variance were used to assess neuropsychological changes as a function of the side in which lesioning was performed (lesioning on the left side compared with that on the right) and surgery (presurgery compared with postsurgery). Relationships between cognitive variables and patient age at disease onset, age at surgery, and disease duration were examined using a linear regression model. The most striking findings were evident from results of a phonemic word fluency test in which patients in whom a left-sided pallidotomy had been performed achieved a mean performance score that was lower than the score of patients in whom a right-sided pallidotomy had been performed; this score declined even more as a result of surgery. Change in performance on the word fluency test across pre- and postoperative assessments was also related to patient age at onset of PD in those who had undergone left-sided pallidotomy, with patients of an older age at disease onset showing the greatest decline in performance.

CONCLUSIONS

These preliminary findings indicate that the side on which surgery was performed and patient age at onset of PD are important in the prediction of postoperative cognitive outcome. The findings also indicate that stereotactically guided lesioning of the GPi presents a relatively mild cognitive risk.

Stereotactic radiofrequency ablation for the treatment of gelastic seizures associated with hypothalamic hamartoma. Case report

The author presents the case of a patient with gelastic seizures associated with a hypothalamic hamartoma, in whom partial resection of the hamartoma followed by temporal lobectomy and orbitofrontal corticectomy failed to reduce the seizures. Subsequent stereotactic radiofrequency ablation of the hamartoma resulted in progressive improvement in the seizure disorder during a 28-month follow-up period. There is support in the literature for the concept that gelastic seizures originate directly from the hamartoma; however, direct surgical approaches to these lesions pose significant risks. It is proposed that the technique of radiofrequency ablation provides a minimally invasive, low-risk approach for the treatment of hypothalamic hamartomas.

Stereotactic amygdalohippocampotomy for the treatment of medial temporal lobe epilepsy

PURPOSE

This study was carried out to assess the safety and efficacy of stereotactic ablation of the amygdala and hippocampus for the treatment of medial temporal lobe epilepsy.

METHODS

Twenty-two stereotactic amygdalohippocampotomies were performed in 19 patients with unilateral temporal lobe seizures by using magnetic resonance imaging (MRI) localization for target planning and radiofrequency techniques for lesion production. Seizure frequency was assessed at 3-monthly follow-up visits. Two lesion groups were defined. In group I, four to 11 (mean, 6.4) discrete lesions were made, encompassing the amygdala and anterior 13-21 mm (mean, 16.8 mm) of the hippocampus. In group II, a large number of confluent lesions were made (mean, 26.0; range, 12-54) encompassing the amygdala and anterior 15-34 mm (mean, 21.5 mm) of the hippocampus. MRI scanning was carried out 24 h and 6-9 months after surgery.

RESULTS

In five group I patients, one (20%) experienced a favorable seizure outcome. Of 15 group II patients, one of whom had previously undergone limited lesioning and was also analyzed as part of group I, nine (60%) experienced a favorable seizure outcome, with two seizure free. MRI scans at 6- to 9-months' follow-up disclosed discrete areas of atrophy in the amygdala and hippocampus, interspersed with preserved brain in the group I patients. More uniform and complete destruction of amygdala and hippocampus was evident in group II patients. All lesions were confined to the amygdala and hippocampus, sparing the parahippocampal gyrus (PHG).

CONCLUSIONS

The extensive amygdalohippocampal ablation in group II patients improved seizure outcome compared with more limited ablation in group I, but these results were not so good as those from temporal lobectomy in a similar patient group. When considered together with the results of selective amygdalohippocampectomy, and temporal resections that spare hippocampus or amygdala (all producing similar outcomes, and all involving resection of the entorhinal cortex), this study suggests a pivotal role of the entorhinal cortex in temporal epileptogenesis.

MR in temporal lobe epilepsy: analysis with pathologic confirmation

PURPOSE

We evaluated the MR findings in patients with temporal lobe epilepsy to determine the predictive value of MR imaging in assessing patient outcome.

METHODS

MR studies from 186 of 274 consecutive patients who underwent temporal lobectomy for intractable epilepsy were reviewed retrospectively. Images were interpreted by an experienced neuroradiologist, who was blinded to the side of seizure activity and to pathologic findings.

RESULTS

MR imaging exhibited 93% sensitivity and 83% specificity in detecting hippocampal/amygdalar abnormalities (n = 121), and 97% sensitivity and 97% specificity in detecting abnormalities in the rest of the temporal lobe (n = 60). Abnormal high signal of the hippocampus on T2-weighted images had a sensitivity of 93% and specificity of 74% in predicting mesial temporal sclerosis (n = 115). The presence of hippocampal atrophy on MR correlated with the duration of seizures. Sensitivity and specificity of MR imaging in detecting temporal lobe tumors (n = 42) were 83% and 97%, respectively, based on abnormal signal and mass effect. After surgery, 63% of patients were seizure free and 28% had a significant reduction of seizure frequency at an average of 24 months (range, 12 to 78 months) after surgery. Patients with a single lesion in the anterior temporal lobe or hippocampus/amygdala had a better outcome than patients with multiple lesions (n = 22). Interrater agreement varied from 0.4 to 0.93, with best agreement for tumors or abnormal hippocampal signal on T2-weighted images.

CONCLUSION

MR imaging is highly sensitive in detecting and locating abnormalities in the temporal lobe and the hippocampus/amygdala in patients with temporal lobe epilepsy. Hippocampal atrophy appears to correspond to the duration of seizure disorder.

Stereotactic amygdalohippocampotomy and mesial temporal spikes

PURPOSE

To investigate the mechanism of mesial temporal spike generation, we sought to determine whether amygdalohippocampotomy by radiofrequency lesions altered spike rates in patients with medically intractable temporal lobe epilepsy.

METHODS

The subjects were 14 patients whose ictal semiology, ictal and interictal EEGs, and neuropsychological profile were compatible with seizure origin from MRI-demonstrated unilateral mesial temporal sclerosis. Mesial temporal spikes were recorded by a multicontact electrode line stereotactically placed in the temporal horn of the lateral ventricle. A recording and lesioning electrode was also stereotactically advanced to multiple amygdala and hippocampal targets. Several confluent (9 patients) or discrete (5 patients) radiofrequency lesions were made in the amygdala and anterior hippocampus. Scalp and invasive recordings were performed before lesioning, between each lesioning process, and for 48 postoperative h.

RESULTS

As compared to prelesion recordings, no consistent change in anterior and total mesial temporal spike rates occurred intraoperatively or postoperatively. Postlesion: prelesion spike ratios failed to correlate with effectiveness of lesionectomy for seizure control. In contrast, complex partial seizures improved in 13 of 14 patients.

CONCLUSIONS

Amygdala and hippocampal destructive lesions had no consistent effect on meisal temporal spike quantity, but reduced temporal lobe CPS in 13 of 14 patients. This dichotomy suggests that CPS may result from concerted epileptogenesis of the hippocampus, entorhinal cortex, and possibly the amygdala, while the entorhinal cortex alone can produce interictal spikes.

Propofol sedation during awake craniotomy for seizures: electrocorticographic and epileptogenic effects

This prospective study evaluated the effects of propofol sedation on the incidence of intraoperative seizures and the adequacy of electrocorticographic (ECoG) recordings during awake craniotomy performed for the management of refractory epilepsy. Thirty patients scheduled for temporal or frontal lobectomy for epilepsy under bupivacaine scalp block were randomized to receive patient-controlled propofol sedation (PCS) combined with a basal infusion of propofol (n = 15) or neurolept analgesia using an initial bolus dose of fentanyl (0.7 microg/kg) and droperidol (0.04 mg/kg) followed by a fentanyl infusion (n = 15). Propofol administration was suspended 15 min before ECoG recording in the PCS group. The occurrence of inappropriate intraoperative seizures was noted and, based on blind review, the adequacy of ECoG recordings was compared. A higher incidence of intraoperative seizures was noted among the neurolept patients (6 vs 0, P = 0.008). Intraoperatively, ECoG recordings were adequate to proceed with resection in both groups. Evidence of low spike activity on ECoG did not correlate with the type of sedation administered. Higher frequency background ECoG activity was noted among patients who received propofol, but this did not interfere with ECoG interpretation. The use of propofol sedation does not appear to interfere with ECoG during epilepsy surgery, provided administration is suspended at least 15 min before recording.

Propofol sedation during awake craniotomy for seizures: patient-controlled administration versus neurolept analgesia

This prospective study evaluated the safety and efficacy of patient-controlled sedation (PCS) using propofol during awake seizure surgery performed under bupivacaine scalp blocks. Thirty-seven patients were randomized to receive either propofol PCS combined with a basal infusion of propofol (n = 20) or neurolept analgesia using an initial bolus dose of fentanyl and droperidol followed by a fentanyl infusion (n = 17). Both groups received supplemental fentanyl and dimenhydrinate for intraoperative pain and nausea, respectively. Comparisons were made between groups for sedation, memory, and cognitive function, patient satisfaction, and incidence of complications. Levels of intraoperative sedation and patient satisfaction were similar between groups. Memory and cognitive function were well preserved in both groups. The incidence of transient episodes of ventilatory rate depression (<8 bpm) was more frequent among the propofol patients (5 vs 0, P = 0.04), particularly after supplemental doses of opioid. Intraoperative seizures were more common among the neurolept patients (7 vs 0, P = 0.002). PCS using propofol represents an effective alternative to neurolept analgesia during awake seizure surgery performed in a monitored care environment.

Complications of CT-guided stereotactic biopsy of intra-axial brain lesions

A series of 300 consecutive stereotactic biopsies for intra-axial brain lesions performed by one neurosurgeon was critically analyzed regarding complications of the procedure. Complications were incurred by a total of 19 patients (6.3%). Five patients (1.7%) died following the procedure, all due to intracranial hypertension: one from subarachnoid hemorrhage, one from intracerebral hemorrhage, and three from increased edema without hemorrhage. The three patients who died without hemorrhage all had marked intracranial hypertension at the time of biopsy. All five patients who died harbored a glioblastoma multiforme. The surviving 14 patients (4.7%) with complications suffered increased neurological deficit due to hemorrhage. In 10 (3.3%), the deficit was mild and/or transient; in the other four (1.3%), a major deficit was incurred which markedly affected the remainder of the patient's life. Therefore, mortality or major morbidity was seen in 3.0% of patients and minor morbidity in 3.3%. Stereotactic biopsy is a very effective procedure with a complication rate significantly lower than that of craniotomy (particularly in the population of patients selected for stereotactic biopsy), but in a small number of patients the outcome is devastating.

Microinjection of lidocaine into human thalamus: a useful tool in stereotactic surgery

A new method was developed to aid in the localization of the optimal site for a permanent lesion in movement disorder patients undergoing stereotactic thalamotomy. The method involved making small injections of a local anesthetic into the thalamus, which was also useful in assessing any possible side effects that could potentially arise from the lesion. Initial results indicate that 0.5 to 2-microliters injections of 2% lidocaine at appropriate sites in the thalamic ventrocaudal or ventrointermedius nucleus can produce a temporary marked suppression of tremor. In most cases the lidocaine induced effects mimicked those produced by high frequency electrical stimulation delivered to the same site. However, lidocaine had no effect at some sites where stimulation arrested tremor. This technique promises to be useful not only in the treatment of motor disorder patients but also in other cases where functional localization prior to lesioning is desirable.

Tremor reduction by microinjection of lidocaine during stereotactic surgery

We report our experience with lidocaine microinjection into the thalamus in 10 patients undergoing stereotactic thalamotomy for the treatment of Parkinsonian or non-Parkinsonian tremor. 18 injection sites in 4 patients with Parkinson's disease and 22 sites in 6 patients with other forms of tremor have been compared with respect to the effect of microstimulation. In over two thirds of cases the test microinjection replicated the effects of microstimulation. Long term follow up will be required to determine whether lesions made on the basis of lidocaine induced tremor suppression will result in a lower rate of tremor recurrence than those based on stimulation induced tremor suppression. In those patients in whom stimulation induced tremor suppression occurs but tremor arrest cannot be produced with lidocaine microinjection, chronic thalamic stimulation may be an alternative for the long term control of tremor in these patients.

Central pain in the absence of functional sensory thalamus

Since the pioneering publication by Dejerine and Roussy, the thalamus has been commonly implicated in the pathogenesis of central pain. It is well known that cerebral lesions that spare the thalamus as well as both small and large ones within that structure produce similar pain syndromes, but could such pain develop if the thalamus were completely destroyed? CT scans of our patients suggested that it could. Moreover, exhaustive physiological explorations of the thalamus with macro- and microstimulation and microelectrode recordings in 2 more patients in whom CT scans suggested thalamic preservation despite massive suprathalamic infarcts, for the purpose of carrying out deep brain stimulation (DBS), revealed no evidence of ascending or descending diencephalic function. Their sensory examinations were similar to those of patients with congenital hemiatrophy who had undergone hemispherectomy. In 1 case, microstimulation of periaqueductal grey-periventricular grey (PAG-PVG) on the unaffected side of the brain induced the spectrum of responses correctly associated with these areas and during acute stimulation nearly abolished the patient's allodynia and hyperpathia. These observations suggest that processes occurring at a subdiencephalic level (or possibly ipsilaterally) may be involved in the generation of pain. Stroke-induced central pain remains a therapeutic dilemma for the pain surgeon, and the mechanisms underlying this pain state remain a mystery.(ABSTRACT TRUNCATED AT 250 WORDS)