Jeffrey G. Ojemann
Alexey V. Dimov, Ajay Gupta, Brian H. Kopell and Yi Wang
Faithful depiction of the subthalamic nucleus (STN) is critical for planning deep brain stimulation (DBS) surgery in patients with Parkinson’s disease (PD). Quantitative susceptibility mapping (QSM) has been shown to be superior to traditional T2-weighted spin echo imaging (T2w). The aim of the study was to describe submillimeter QSM for preoperative imaging of the STN in planning of DBS.
Seven healthy volunteers were included in this study. T2w and QSM were obtained for all healthy volunteers, and images of different resolutions were reconstructed. Image quality and visibility of STN anatomical features were analyzed by a radiologist using a 5-point scale, and contrast properties of the STN and surrounding tissue were calculated. Additionally, data from 10 retrospectively and randomly selected PD patients who underwent 3-T MRI for DBS were analyzed for STN size and susceptibility gradient measurements.
Higher contrast-to-noise ratio (CNR) values were observed in both high-resolution and low-resolution QSM images. Inter-resolution comparison demonstrated improvement in CNR for QSM, but not for T2w images. QSM provided higher inter-quadrant contrast ratios (CR) within the STN, and depicted a gradient in the distribution of susceptibility sources not visible in T2w images.
For 3-T MRI, submillimeter QSM provides accurate delineation of the functional and anatomical STN features for DBS targeting.
Robert A. McGovern, Elia Pestana Knight, Ajay Gupta, Ahsan N. V. Moosa, Elaine Wyllie, William E. Bingaman and Jorge Gonzalez-Martinez
The goal in the study was to describe the clinical outcomes associated with robot-assisted stereoelectroencephalography (SEEG) in children.
The authors performed a retrospective, single-center study in consecutive children with medically refractory epilepsy who were undergoing robot-assisted SEEG. Kaplan-Meier survival analysis was used to calculate the probability of seizure freedom. Both univariate and multivariate methods were used to analyze the preoperative and operative factors associated with seizure freedom.
Fifty-seven children underwent a total of 64 robot-assisted procedures. The patients’ mean age was 12 years, an average of 6.4 antiepileptic drugs (AEDs) per patient had failed prior to implantation, and in 56% of the patients the disease was considered nonlesional. On average, children had 12.4 electrodes placed per implantation, with an implantation time of 9.6 minutes per electrode and a 10-day postoperative stay. SEEG analysis yielded a definable epileptogenic zone in 51 (89%) patients; 42 (74%) patients underwent surgery, half of whom were seizure free at last follow-up, 19.6 months from resection. In a multivariate generalized linear model, resective surgery, older age, and shorter SEEG-related hospital length of stay were associated with seizure freedom. In a Cox proportional hazards model including only the children who underwent resective surgery, older age was the only significant factor associated with seizure freedom. Complications related to bleeding were the major contributors to morbidity. One patient (1.5%) had a symptomatic hemorrhage resulting in a permanent neurological deficit.
The authors report one of the largest pediatric-specific SEEG series demonstrating that the modern surgical management of medically refractory epilepsy in children can lead to seizure freedom in many patients, while also highlighting the challenges posed by this difficult patient population.
Vipul Gupta, Tanvir Rizvi, Ajay Garg, Shailesh B. Gaikwad and N. K. Mishra
✓ The authors report the case of a 30-year-old man who presented with progressive neurological deficits due to a spinal arteriovenous malformation (AVM). There was sudden increase in his neurological deficits after diagnostic angiography was performed. Repeated magnetic resonance imaging and angiography revealed complete thrombosis of the malformation. Stenosis in the draining vein was the most probable cause of this postangiographic occlusion of the AVM. Contrast injection during angiography may have precipitated the thrombosis.
Jeffrey P. Blount
Case report and review of the literature
Tanvir Rizvi, Ajay Garg, Nalini K. Mishra, Shailesh B. Gaikwad and Vipul Gupta
✓ Spinal dural arteriovenous fistulas (DAVFs), the most common of spinal vascular malformations, are AVFs in the dura mater of the nerve root and/or adjacent spinal dura. These fistulas are most often solitary and are fed by a single radicular artery that primarily supplies the dura mater. Multiple spinal DAVFs are rarely reported in the literature. Those that have been documented have been synchronous in their presentation in that they were found during the same examination or were present at the initial examination but missed and only recognized at the second examination. The authors report the case of a patient with two spinal DAVFs occurring at different spinal levels at different points in time (metachronous).
Aditya Gupta, M.Ch., Faiz U. Ahmad, Mehar C. Sharma, Ajay Garg and Veer S. Mehta
✓Meningeal melanocytomas are uncommon intracranial tumors and their occurrence at the cerebellopontine angle (CPA) is extremely rare. The authors describe the case of a 58-year-old woman who presented with a left CPA tumor; on the basis of histopathological studies after resection, a diagnosis of meningeal melanocytoma was reached. The relevant literature is reviewed.
Elia M. Pestana Knight, Tobias Loddenkemper, Deepak Lachhwani, Prakash Kotagal, Elaine Wyllie, William Bingaman and Ajay Gupta
The aim of this study was to identify the reasons for and predictors of no resection of the epileptogenic zone in children with epilepsy who had undergone long-term invasive subdural grid electroencephalography (SDG-EEG) evaluation.
The authors retrospectively reviewed the consecutive medical records of children (< 19 years of age) who had undergone SDG-EEG evaluation over a 7-year period (1997–2004). To determine the predictors of no resection, the authors obtained the clinical characteristics and imaging and EEG findings of children who had no resection after long-term invasive SDG-EEG evaluation and compared these data with those in a group of children who did undergo resection. They describe the indications for SDG-EEG evaluation and the reasons for no resection in these patients.
Of 66 children who underwent SDG-EEG evaluation, 9 (13.6%) did not undergo subsequent resection (no-resection group; 6 males). Of these 9 patients, 6 (66.7%) had normal neurological examinations and 5 (55.6%) had normal findings on brain MR imaging. Scalp video EEG localized epilepsy to the left hemisphere in 6 of the 9 patients and to the right hemisphere in 2; it was nonlocalizable in 1 of the 9 patients. Indications for SDG-EEG in the no-resection group were ictal onset zone (IOZ) localization (9 of 9 patients), motor cortex localization (5 of 9 patients), and language area localization (4 of 9 patients). Reasons for no resection after SDG-EEG evaluation were the lack of a well-defined IOZ in 5 of 9 patients (4 multifocal IOZs and 1 nonlocalizable IOZ) and anticipated new permanent postoperative neurological deficits in 7 of 9 patients (3 motor, 2 language, and 2 motor and language deficits). Comparison with the resection group (57 patients) demonstrated that postictal Todd paralysis in the dominant hand was the only variable seen more commonly (χ2 = 4.781, p = 0.029) in the no-resection group (2 [22.2%] of 9 vs 2 [3.5%] of 57 patients). The no-resection group had a larger number of SDG electrode contacts (mean 126. 5 ± 26.98) as compared with the resection group (100.56 ± 25.52; p = 0.010). There were no significant differences in the demographic data, seizure characteristics, scalp and invasive EEG findings, and imaging variables between the resection and no-resection groups.
Children who did not undergo resection of the epileptogenic zone after SDG-EEG evaluation were likely to have normal neurological examinations without preexisting neurological deficits, a high probability of a new unacceptable permanent neurological deficit following resection, or multifocal or nonlocalizable IOZs. In comparison with the group that underwent resection after SDG-EEG, a history of Todd paralysis in the dominant hand and arm was the only predictor of no resection following SDG-EEG evaluation. Data in this study will help to better select pediatric patients for SDG-EEG and to counsel families prior to epilepsy surgery.
Case report and review of the literature
Ajay Garg, Manish Chugh, Shailesh B. Gaikwad, Sarat P. Chandra, Vipul Gupta, Nalin K. Mishra and Mehar Chand Sharma
✓ The authors report a case of a 13-year-old boy with juvenile pilocytic astrocytoma (JPA) presenting with subarachnoid hemorrhage (SAH). The patient experienced sudden onset of headache, vomiting, and loss of consciousness. Cranial computerized tomography scanning revealed blood within basal cisterns and the third ventricle. Angiography demonstrated normal cerebral vasculature and upward displacement of the bilateral A1 segments of the anterior cerebral artery. Magnetic resonance (MR) imaging revealed a chiasmatic/hypothalamic mass with evidence of hemorrhage. The mass was surgically decompressed. Histopathological examination showed evidence of JPA. In all cases of SAH in which there is blood around the third ventricle and a raised A1 segment on angiography, MR imaging should be performed. The presence of a normal sella turcica, as well as indistinct margins between the tumor and the opticochiasmatic apparatus should raise suspicion about the lesion.
Shaila Gowda, Fortino Salazar, William E. Bingaman, Prakash Kotagal, Deepak L. Lachhwani, Ajay Gupta, Stephen Davis, Julie Niezgoda and Elaine Wyllie
Few data are available concerning efficacy and safety of surgery for catastrophic epilepsy in the first 6 months of life.
The authors retrospectively analyzed epilepsy surgeries in 15 infants ranging in age from 1.5 to 6 months (median 4 months) and weight from 4 to 10 kg (median 7 kg) who underwent anatomical (4 patients) or functional (7 patients) hemispherectomy, or frontal (1 patient), frontoparietal (2 patients), or parietooccipital (1 patient) resection for life-threatening catastrophic epilepsy due to malformation of cortical development.
No patient died. Intraoperative complications included an acute ischemic infarction with hemiparesis in our youngest, smallest infant. The most frequent complication was blood loss requiring transfusion, which was encountered in every case. The estimated blood loss was 3–214% (median 63%) of the total blood volume. At maximum follow-up of 6–121 months (median 60 months), 46% were seizure free.
Epilepsy surgery may be effective in young infants as it is in older children. However, intraoperative blood loss and risk of permanent postoperative neurological deficits present significant challenges.