Neck atonia with a focal stimulation-induced seizure arising from the SMA: pathophysiological considerations.

A 28-year-old patient with pharmacoresistant non-lesional right frontal epilepsy underwent extra-operative intracranial EEG recordings and electrical cortical stimulation (ECS) to map eloquent cortex. Right supplementary motor area (SMA) ECS induced a brief seizure with habitual symptoms involving neck tingling followed by asymmetric tonic posturing. An additional feature was neck atonia. During atonia and sensory aura, discharges were seen in the mesial frontal electrodes and precentral gyrus. Besides motor signs, atonia, although rare and not described in the neck muscles, and sensations have been reported with SMA stimulation. The mechanisms underlying neck atonia in seizures arising from the SMA can be explained by supplementary negative motor area (SNMA) - though this was not mapped in electrodes overlying the ictal onset zone in our patient - or primary sensorimotor cortex activation through rapid propagation. Given the broad spectrum of signs elicited by SMA stimulation and rapid spread of seizures arising from the SMA, caution should be taken to not diagnose these as non-epileptic, as had previously occurred in this patient

Stability, Structure and Scale: Improvements in Multi-modal Vessel Extraction for SEEG Trajectory Planning

Purpose Brain vessels are among the most critical landmarks that need to be assessed for mitigating surgical risks in stereo-electroencephalography (SEEG) implantation. Intracranial haemorrhage is the most common complication associated with implantation, carrying signi cant associated morbidity. SEEG planning is done pre-operatively to identify avascular trajectories for the electrodes. In current practice, neurosurgeons have no assistance in the planning of electrode trajectories. There is great interest in developing computer assisted planning systems that can optimise the safety pro le of electrode trajectories, maximising the distance to critical structures. This paper presents a method that integrates the concepts of scale, neighbourhood structure and feature stability with the aim of improving robustness and accuracy of vessel extraction within a SEEG planning system. Methods The developed method accounts for scale and vicinity of a voxel by formulating the problem within a multi-scale tensor voting framework. Feature stability is achieved through a similarity measure that evaluates the multi-modal consistency in vesselness responses. The proposed measurement allows the combination of multiple images modalities into a single image that is used within the planning system to visualise critical vessels. Results Twelve paired datasets from two image modalities available within the planning system were used for evaluation. The mean Dice similarity coe cient was 0.89 ± 0.04, representing a statistically signi cantly improvement when compared to a semi-automated single human rater, single-modality segmentation protocol used in clinical practice (0.80 ±0.03). Conclusions Multi-modal vessel extraction is superior to semi-automated single-modality segmentation, indicating the possibility of safer SEEG planning, with reduced patient morbidity

Primary enucleation for group D retinoblastoma in the era of systemic and targeted chemotherapy: the price of retaining an eye

BACKGROUND: Chemotherapy is increasingly used as primary treatment for group D retinoblastoma, whereas primary enucleation is considered to have a diminishing role. This study aimed to compare the management course, including number of examinations under anaesthesia (EUAs), of group D patients treated by enucleation versus chemotherapy. METHODS: A retrospective analysis of 92 group D patients, of which 40 (37 unilateral) underwent primary enucleation and 52 (17 unilateral) were treated with intravenous chemotherapy. Number of EUAs was compared between the treatment groups with respect to the whole cohort, using univariate and multivariate analysis, and to unilateral cases only. RESULTS: Patients were followed up for a median of 61 months (mean: 66, range: 14-156), in which time primary enucleated patients had on average seven EUAs and chemotherapy-treated patients 21 EUAs (p<0.001). Chemotherapy, young age, bilateral disease, multifocal tumours, familial and germline retinoblastoma were found on univariate analysis to correlate with increased number of EUAs (p≤0.019). On multivariate analysis, however, only treatment type and presentation age were found significant (p≤0.001). On subanalysis of the unilateral cases, patients undergoing primary enucleation had in average seven EUAs, as compared with 16 in the chemotherapy group (p<0.001). Of the 55 unilateral-presenting patients, a new tumour developed in the fellow eye only in a single familial case. CONCLUSION: Group D patients' families should be counselled regarding the significant difference in number of EUAs following primary enucleation versus chemotherapy when deciding on a treatment strategy. In this regard, primary enucleation would be most beneficial for older patients with unilateral disease

Optic radiation tractography and vision in anterior temporal lobe resection.

Anterior temporal lobe resection (ATLR) is an effective treatment for refractory temporal lobe epilepsy but may result in a contralateral superior visual field deficit (VFD) that precludes driving in the seizure-free patient. Diffusion tensor imaging (DTI) tractography can delineate the optic radiation preoperatively and stratify risk. It would be advantageous to incorporate display of tracts into interventional magnetic resonance imaging (MRI) to guide surgery

Memory network plasticity after temporal lobe resection: a longitudinal functional imaging study

Anterior temporal lobe resection can control seizures in up to 80% of patients with temporal lobe epilepsy. Memory decrements are the main neurocognitive complication. Preoperative functional reorganization has been described in memory networks, but less is known of postoperative reorganization. We investigated reorganization of memory-encoding networks preoperatively and 3 and 12 months after surgery. We studied 36 patients with unilateral medial temporal lobe epilepsy (19 right) before and 3 and 12 months after anterior temporal lobe resection. Fifteen healthy control subjects were studied at three equivalent time points. All subjects had neuropsychological testing at each of the three time points. A functional magnetic resonance imaging memory-encoding paradigm of words and faces was performed with subsequent out-of-scanner recognition assessments. Changes in activations across the time points in each patient group were compared to changes in the control group in a single flexible factorial analysis. Postoperative change in memory across the time points was correlated with postoperative activations to investigate the efficiency of reorganized networks. Left temporal lobe epilepsy patients showed increased right anterior hippocampal and frontal activation at both 3 and 12 months after surgery relative to preoperatively, for word and face encoding, with a concomitant reduction in left frontal activation 12 months postoperatively. Right anterior hippocampal activation 12 months postoperatively correlated significantly with improved verbal learning in patients with left temporal lobe epilepsy from preoperatively to 12 months postoperatively. Preoperatively, there was significant left posterior hippocampal activation that was sustained 3 months postoperatively at word encoding, and increased at face encoding. For both word and face encoding this was significantly reduced from 3 to 12 months postoperatively. Patients with right temporal lobe epilepsy showed increased left anterior hippocampal activation on word encoding from 3 to 12 months postoperatively compared to preoperatively. On face encoding, left anterior hippocampal activations were present preoperatively and 12 months postoperatively. Left anterior hippocampal and orbitofrontal cortex activations correlated with improvements in both design and verbal learning 12 months postoperatively. On face encoding, there were significantly increased left posterior hippocampal activations that reduced significantly from 3 to 12 months postoperatively. Postoperative changes occur in the memory-encoding network in both left and right temporal lobe epilepsy patients across both verbal and visual domains. Three months after surgery, compensatory posterior hippocampal reorganization that occurs is transient and inefficient. Engagement of the contralateral hippocampus 12 months after surgery represented efficient reorganization in both patient groups, suggesting that the contralateral hippocampus contributes to memory outcome 12 months after surgery

Cognitive outcomes of temporal lobe epilepsy surgery in older patients

Purpose: To examine the cognitive risks of temporal lobe surgery in patients aged 50 years and older. / Methods: We analysed data from 55 patients who underwent temporal lobe surgery (26 left-sided:29 right sided) from 1988 to 2012 at our centre. Pre-surgical and one year post-operative memory and naming capacity were compared to data obtained from two younger cohorts; 185 aged 18–30 and 220 aged 31–49. / Results: Pre-operative memory impairments were most marked for the oldest cohort and were associated with a longer duration of epilepsy. Naming capacity improved with age and better performance was associated with a later age at epilepsy onset. Post-operative declines were largest in older patients, achieving statistical significance for verbal memory, naming and subjective ratings. Left temporal lobe resections carried the greatest risk of memory and naming decline. Cognitive outcomes were unrelated to seizure outcome, VIQ or mood. / Conclusion: Our findings indicate the cognitive risks of TLE surgery are greater for older patients. Cognitive outcomes need to be considered when assessing the efficacy of epilepsy surgery in older cohorts and pre-operative performance levels need to be taken into account

Memory reorganization following anterior temporal lobe resection: a longitudinal functional MRI study

Anterior temporal lobe resection controls seizures in 50-60% of patients with intractable temporal lobe epilepsy but may impair memory function, typically verbal memory following left, and visual memory following right anterior temporal lobe resection. Functional reorganization can occur within the ipsilateral and contralateral hemispheres. We investigated the reorganization of memory function in patients with temporal lobe epilepsy before and after left or right anterior temporal lobe resection and the efficiency of postoperative memory networks. We studied 46 patients with unilateral medial temporal lobe epilepsy (25/26 left hippocampal sclerosis, 16/20 right hippocampal sclerosis) before and after anterior temporal lobe resection on a 3 T General Electric magnetic resonance imaging scanner. All subjects had neuropsychological testing and performed a functional magnetic resonance imaging memory encoding paradigm for words, pictures and faces, testing verbal and visual memory in a single scanning session, preoperatively and again 4 months after surgery. Event-related analysis revealed that patients with left temporal lobe epilepsy had greater activation in the left posterior medial temporal lobe when successfully encoding words postoperatively than preoperatively. Greater pre- than postoperative activation in the ipsilateral posterior medial temporal lobe for encoding words correlated with better verbal memory outcome after left anterior temporal lobe resection. In contrast, greater postoperative than preoperative activation in the ipsilateral posterior medial temporal lobe correlated with worse postoperative verbal memory performance. These postoperative effects were not observed for visual memory function after right anterior temporal lobe resection. Our findings provide evidence for effective preoperative reorganization of verbal memory function to the ipsilateral posterior medial temporal lobe due to the underlying disease, suggesting that it is the capacity of the posterior remnant of the ipsilateral hippocampus rather than the functional reserve of the contralateral hippocampus that is important for maintaining verbal memory function after anterior temporal lobe resection. Early postoperative reorganization to ipsilateral posterior or contralateral medial temporal lobe structures does not underpin better performance. Additionally our results suggest that visual memory function in right temporal lobe epilepsy is affected differently by right anterior temporal lobe resection than verbal memory in left temporal lobe epilepsy

The impact of epilepsy surgery on the structural connectome and its relation to outcome

BACKGROUND: Temporal lobe surgical resection brings seizure remission in up to 80% of patients, with long-term complete seizure freedom in 41%. However, it is unclear how surgery impacts on the structural white matter network, and how the network changes relate to seizure outcome. METHODS: We used white matter fibre tractography on preoperative diffusion MRI to generate a structural white matter network, and postoperative T1-weighted MRI to retrospectively infer the impact of surgical resection on this network. We then applied graph theory and machine learning to investigate the properties of change between the preoperative and predicted postoperative networks. RESULTS: Temporal lobe surgery had a modest impact on global network efficiency, despite the disruption caused. This was due to alternative shortest paths in the network leading to widespread increases in betweenness centrality post-surgery. Measurements of network change could retrospectively predict seizure outcomes with 79% accuracy and 65% specificity, which is twice as high as the empirical distribution. Fifteen connections which changed due to surgery were identified as useful for prediction of outcome, eight of which connected to the ipsilateral temporal pole. CONCLUSIONS: Our results suggest that the use of network change metrics may have clinical value for predicting seizure outcome. This approach could be used to prospectively predict outcomes given a suggested resection mask using preoperative data only

Comparison of robotic and manual implantation of intracerebral electrodes: a single-centre, single-blinded, randomised controlled trial

There has been a significant rise in robotic trajectory guidance devices that have been utilised for stereotactic neurosurgical procedures. These devices have significant costs and associated learning curves. Previous studies reporting devices usage have not undertaken prospective parallel-group comparisons before their introduction, so the comparative differences are unknown. We study the difference in stereoelectroencephalography electrode implantation time between a robotic trajectory guidance device (iSYS1) and manual frameless implantation (PAD) in patients with drug-refractory focal epilepsy through a single-blinded randomised control parallel-group investigation of SEEG electrode implantation, concordant with CONSORT statement. Thirty-two patients (18 male) completed the trial. The iSYS1 returned significantly shorter median operative time for intracranial bolt insertion, 6.36 min (95% CI 5.72–7.07) versus 9.06 min (95% CI 8.16–10.06), p = 0.0001. The PAD group had a better median target point accuracy 1.58 mm (95% CI 1.38–1.82) versus 1.16 mm (95% CI 1.01–1.33), p = 0.004. The mean electrode implantation angle error was 2.13° for the iSYS1 group and 1.71° for the PAD groups (p = 0.023). There was no statistically significant difference for any other outcome. Health policy and hospital commissioners should consider these differences in the context of the opportunity cost of introducing robotic devices