Feasibility of cerebello-cortical stimulation for intraoperative neurophysiological monitoring of cerebellar mutism

BACKGROUND: Cerebellar mutism can occur in a third of children undergoing cerebellar resections. Recent evidence proposes it may arise from uni- or bilateral damage of cerebellar efferents to the cortex along the cerebello-dento-thalamo-cortical pathway. At present, no neurophysiological procedure is available to monitor this pathway intraoperatively. Here, we specifically aimed at filling this gap.METHODS: We assessed 10 patients undergoing posterior fossa surgery using a conditioning-test stimulus paradigm. Electrical conditioning stimuli (cStim) were delivered to the exposed cerebellar cortex at interstimulus intervals (ISIs) of 8-24 ms prior to transcranial electric stimulation of the motor cortex, which served as test stimulus (tStim). The variation of motor-evoked potentials (MEP) to cStim + tStim compared with tStim alone was taken as a measure of cerebello-cortical connectivity.RESULTS: cStim alone did not produce any MEP. cStim preceding tStim produced a significant inhibition at 8 ms (p < 0.0001) compared with other ISIs when applied to the lobules IV-V-VI in the anterior cerebellum and the lobule VIIB in the posterior cerebellum. Mixed effects of decrease and increase in MEP amplitude were observed in these areas for longer ISIs.CONCLUSIONS: The inhibition exerted by cStim at 8 ms on the motor cortex excitability is likely to be the product of activity along the cerebello-dento-thalamo-cortical pathway. We show that monitoring efferent cerebellar pathways to the motor cortex is feasible in intraoperative settings. This study has promising implications for pediatric posterior fossa surgery with the aim to preserve the cerebello-cortical pathways and thus prevent cerebellar mutism

Long-term motor deficit in brain tumour surgery with preserved intra-operative motor-evoked potentials

Muscle motor-evoked potentials are commonly monitored during brain tumour surgery in motor areas, as these are assumed to reflect the integrity of descending motor pathways, including the corticospinal tract. However, while the loss of muscle motor-evoked potentials at the end of surgery is associated with long-term motor deficits (muscle motor-evoked potential-related deficits), there is increasing evidence that motor deficit can occur despite no change in muscle motor-evoked potentials (muscle motor-evoked potential-unrelated deficits), particularly after surgery of non-primary regions involved in motor control. In this study, we aimed to investigate the incidence of muscle motor-evoked potential-unrelated deficits and to identify the associated brain regions. We retrospectively reviewed 125 consecutive patients who underwent surgery for peri-Rolandic lesions using intra-operative neurophysiological monitoring. Intraoperative changes in muscle motor-evoked potentials were correlated with motor outcome, assessed by the Medical Research Council scale. We performed voxel-lesion-symptom mapping to identify which resected regions were associated with short- and long-term muscle motor-evoked potential-associated motor deficits. Muscle motor-evoked potentials reductions significantly predicted long-term motor deficits. However, in more than half of the patients who experienced long-term deficits (12/22 patients), no muscle motor-evoked potential reduction was reported during surgery. Lesion analysis showed that muscle motor-evoked potential-related long-term motor deficits were associated with direct or ischaemic damage to the corticospinal tract, whereas muscle motor-evoked potential-unrelated deficits occurred when supplementary motor areas were resected in conjunction with dorsal premotor regions and the anterior cingulate. Our results indicate that long-term motor deficits unrelated to the corticospinal tract can occur more often than currently reported. As these deficits cannot be predicted by muscle motor-evoked potentials, a combination of awake and/or novel asleep techniques other than muscle motor-evoked potentials monitoring should be implemented

Updates on Intraoperative Neurophysiology During Surgery for Spinal Dysraphism

Spinal dysraphism is a group of disorders resulting from an embryologic failure of spinal cord development which can lead to a radicular-medullary mechanical stretch that generates vascular compromise and hypoxic-ischemic damage to the nervous structures of the conus-cauda region.Thus, the clinical relevance of the different types of spinal dysraphism is related to the possible neurologic deficits resulting from spinal cord tethering. The clinical presentation is heterogenous: from asymptomatic to very compromised patients. The indications and the time of a detethering surgery are still subject of debate, although there is an agreement on the high standards of treatment that have to be offered by the surgery. Intraoperative neurophysiology (ION) contributes to the safety of tethered cord surgery in reducing the risks of iatrogenic neurological damages

Intraoperative neuromonitoring predicts motor recovery in a long-term hemiplegic patient with a Rolandic metastasis

Letter. [no abstract available

Intra-operative neurophysiological mapping and monitoring during brain tumour surgery in children: an update

Over the past decade, the reluctance to operate in eloquent brain areas has been reconsidered in the light of the advent of new peri-operative functional neuroimaging techniques and new evidence from neuro-oncology. To maximise tumour resection while minimising morbidity should be the goal of brain surgery in children as much as it is in adults, and preservation of brain functions is critical in the light of the increased survival and the expectations in terms of quality of life

Utility of preoperative electrodiagnosis together with peripheral nerve high-resolution ultrasound: a complex case report of Neurofibromatosis type I

Our case report underscores the importance of electroneuromyography (ENMG) combined with peripheral nerve high-resolution ultrasound (HRUS) in the evaluation of neurofibromatosis type 1 (NF1). A 49-year-old woman affected by NF1 came to our attention because of new-onset left arm weakness and atrophy. Debulking of a cervicothoracic C7-T1 neurofibroma had been performed 8 years earlier. On current admission, magnetic resonance imaging disclosed increased lesion volume that was thought to cause the neurologic deficits by compressing the C8 root. Findings from intraoperative neurophysiologic monitoring during repeat debulking suggested that C8 root integrity had been compromised during the first operation and that the new-onset symptoms probably stemmed from peripheral nervous system damage distal to the cervical roots. Postoperative ENMG showed chronic denervation signs in the muscles innervated by C7-C8-T1 roots, moderate carpal tunnel syndrome (CTS), and ulnar nerve conduction block at the elbow. HRUS confirmed the CTS and revealed multiple neurofibromas involving the distal tract of the radial, ulnar, and median nerves. Surgical debulking was considered unnecessary in this case. ENMG combined with nerve and plexus HRUS evaluation may help identify the cause of neurologic deficits and choose the best surgical option in such complex clinical conditions as NF1

Reply to "Intraoperative cortico-cortical evoked potentials for monitoring the arcuate fasciculus: Feasible under general anesthesia?"

No abstract availabl

Very early and early neurophysiological abnormalities in Guillain-Barr\ue9 Syndrome: a 4-year retrospective study

In its initial stages, Guillain Barr\ue9 syndrome (GBS) is difficult to identify because diagnostic criteria may not always be fulfilled. With this retrospective study, we wanted to identify the most common electrophysiological abnormalities seen on neurophysiological examination of GBS patients and its variants in the early phases

Genetic profile of patients with early onset inflammatory bowel disease

Inflammatory Bowel disease (IBD) is a widespread pathological condition with clinical heterogeneity and with different levels of severity. Although IBD usually occurs in young adults, onset in childhood and infancy are described in patients within the 10th and second year of age. By genome-wide association studies and meta-analysis several genetic loci have been identified associated with an increased risk of developing IBD in Western populations with variants that may alter the normal mucosal immunity in the gastrointestinal tract. The clinical complexity and the heterogeneity of the IBD phenotype probably reflect the presence of genetic heterogeneity where different genes or combinations of them may be involved, together with environmental factors. We hypothesized that patients with early onset IBD could have either more severe genetic variants in genes associated with IBD or multiple variants in different genes. Under the multifactorial diseases is crucial to consider the small contribution of a single variant in all not only to other small variations in the same gene but also in different genes belonging to the same pathway. We performed direct gene sequencing looking for 94 variations in NOD2, ATG16L1, IL23R, IL10R, IL10 and XIAP genes previously shown as correlated with IBD both in multifactorial and in Mendelian models. All variants identified are known in literature as being associated with IBD except for three variants in the genes NOD2, IL10 and IL10RB that even though present in online databases have never been involved in association studies on IBD patients. Moreover, we coupled genetic variants identification with an accurate \u201cin silico\u201d analysis to verify their predictive impact on the protein structure and function. The in-silico prediction of these variants results as benign therefore even if they exhibit a very low frequency in control population being benign, they cannot be considered pathogenic as monogenic disease but fall within the multifactorial range. The variants identified in our study partially reflect the association data described in the literature but there are no significant differences with the onset of disease (VEO vs EO-IBD)