Despite long-term and widespread use of deep brain stimulation (DBS) in a variety of neurological conditions, the underlying mechanisms of action have been elusive. Growing evidence suggests that DBS acts through multimodal mechanisms that are not limited to inhibition and excitation of basal ganglia circuits. DBS also seems to act over variable time spans - for example, the effects on tremor are immediate, whereas the effects on dystonia emerge over several weeks - suggesting that large networks are targeted. Studies reviewing the use of DBS in pain and obsessive-compulsive disorder have demonstrated direct involvement of axonal fibres rather than grey matter. In this Review, we draw on clinical and experimental data to examine the various hypotheses that have been put forward to explain the effects of DBS. In agreement with several other experts, we suggest that the term 'deep brain stimulation' warrants modification. A potentially more accurate term is 'deep brain neuromodulation', as the mode of action spans an array of therapeutic effects over a variable period of time, and is not just limited to 'stimulation' of the basal ganglia brain centres. Terms such as 'electrical neuro-network modulation' may be useful for applications in which deep brain structures are not the primary target.

Background Surgery is the main modality of cure for solid cancers and was prioritised to continue during COVID-19 outbreaks. This study aimed to identify immediate areas for system strengthening by comparing the delivery of elective cancer surgery during the COVID-19 pandemic in periods of lockdown versus light restriction. Methods This international, prospective, cohort study enrolled 20 006 adult (≥18 years) patients from 466 hospitals in 61 countries with 15 cancer types, who had a decision for curative surgery during the COVID-19 pandemic and were followed up until the point of surgery or cessation of follow-up (Aug 31, 2020). Average national Oxford COVID-19 Stringency Index scores were calculated to define the government response to COVID-19 for each patient for the period they awaited surgery, and classified into light restrictions (index <20), moderate lockdowns (20–60), and full lockdowns (>60). The primary outcome was the non-operation rate (defined as the proportion of patients who did not undergo planned surgery). Cox proportional-hazards regression models were used to explore the associations between lockdowns and non-operation. Intervals from diagnosis to surgery were compared across COVID-19 government response index groups. This study was registered at ClinicalTrials.gov , NCT04384926 . Findings Of eligible patients awaiting surgery, 2003 (10·0%) of 20 006 did not receive surgery after a median follow-up of 23 weeks (IQR 16–30), all of whom had a COVID-19-related reason given for non-operation. Light restrictions were associated with a 0·6% non-operation rate (26 of 4521), moderate lockdowns with a 5·5% rate (201 of 3646; adjusted hazard ratio [HR] 0·81, 95% CI 0·77–0·84; p<0·0001), and full lockdowns with a 15·0% rate (1775 of 11 827; HR 0·51, 0·50–0·53; p<0·0001). In sensitivity analyses, including adjustment for SARS-CoV-2 case notification rates, moderate lockdowns (HR 0·84, 95% CI 0·80–0·88; p<0·001), and full lockdowns (0·57, 0·54–0·60; p<0·001), remained independently associated with non-operation. Surgery beyond 12 weeks from diagnosis in patients without neoadjuvant therapy increased during lockdowns (374 [9·1%] of 4521 in light restrictions, 317 [10·4%] of 3646 in moderate lockdowns, 2001 [23·8%] of 11 827 in full lockdowns), although there were no differences in resectability rates observed with longer delays. Interpretation Cancer surgery systems worldwide were fragile to lockdowns, with one in seven patients who were in regions with full lockdowns not undergoing planned surgery and experiencing longer preoperative delays. Although short-term oncological outcomes were not compromised in those selected for surgery, delays and non-operations might lead to long-term reductions in survival. During current and future periods of societal restriction, the resilience of elective surgery systems requires strengthening, which might include...

Cortical and thalamic stimulation appear to be effective and well tolerated in children with refractory epilepsy. SCS can be used to identify the focus and predict the effects of resective surgery or chronic cortical stimulation. Further larger studies are necessary.

Cerebral abscess is an emergency requiring urgent drainage via craniotomy or burrhole aspiration. We examine whether initial method of drainage affects outcome and important characteristics in patients with cerebral abscess. This is a retrospective analysis of 62 patients operated on in our unit with a loculated infected cerebral collection in the years 2003-2007 inclusive. Full statistical analysis was performed using data appropriate tests. Burrhole and craniotomy groups were evenly matched with no difference in any demographic factors. Surgical method made no difference to rate of re-operation (p = 0.276), antibiotic duration (p = 0.648), discharge GCS (p = 0.509), length of stay (p = 0.647) or GOS (p = 0.968). There was a trend to worsened outcome with delay to surgery (p = 0.132) with delayed patients requiring longer hospital stays (p< or = 0.005). Patients requiring a longer antibiotic duration had worse outcomes (p < or = 0.005). Surgical method did not have a significant effect on outcome, so burrhole aspiration with its advantages in terms of speed and scale of surgery should be strongly considered. Delay had an adverse affect, so operation should be as expeditious as possible whenever the differential diagnosis includes abscess, diagnosis of which may be aided by advanced magnetic resonance imaging techniques.

Epilepsia partialis continua (EPC), defined as a syndrome of continuous focal jerking, is a rare form of focal status epilepticus that usually affects a distal limb, and when prolonged, can produce long-lasting deficits in limb function. Substantial electrophysiologic evidence links the origin of EPC to the motor cortex; thus surgical resection carries the risk of significant handicap. We present two patients with focal, drug-resistant EPC, who were admitted for intracranial video-electroencephalography monitoring to elucidate the location of the epileptogenic focus and identification of eloquent motor cortex with functional mapping. In both cases, the focus resided at or near eloquent motor cortex and therefore precluded resective surgery. Chronic cortical stimulation delivered through subdural strips at the seizure focus (continuous stimulation at 60-130 Hz, 2-3 mA) resulted in >90% reduction in seizures and abolition of the EPC after a follow-up of 22 months in both patients. Following permanent implantation of cortical stimulators, no adverse effects were noted. EPC restarted when intensity was reduced or batteries depleted. Battery replacement restored previous improvement. This two-case report opens up avenues for the treatment of this debilitating condition.

SDR in comparison to ITB in this subgroup is cheaper, less intrusive by avoiding refills/replacement and found to be more effective than ITB in reducing spasticity and providing ease for nursing care. We therefore suggest that consideration should be given to SDR as an alternative in patients previously implanted with ITB systems complicated by infection or nearing end of battery life.

MRI has a vital role in the assessment of intracranial lesions. Conventional MRI has limited specificity and multiparametric MRI using diffusion-weighted imaging, perfusion-weighted imaging and magnetic resonance spectroscopy allows more accurate assessment of the tissue microenvironment. The purpose of this educational pictorial review is to demonstrate the role of multiparametric MRI for diagnosis, treatment planning and for assessing treatment response, as well as providing a practical approach for performing and interpreting multiparametric MRI in the clinical setting. A variety of cases are presented to demonstrate how multiparametric MRI can help differentiate neoplastic from non-neoplastic lesions compared to conventional MRI alone.

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