1,720,982 research outputs found
Neurophysiological identification of long sensory and motor tracts within the spinal cord
No full text
Letter to the Editor: Electrical activity in limb muscles after spinal cord stimulation is not specific for the corticospinal tract.
No full text[no abstract available
Selective dorsal rhizotomy: functional anatomy of the conus-cauda and essentials of intraoperative neurophysiology
No full textIntroduction: Spasticity is the result of an exaggeration of the monosynaptic muscle stretch reflex due to lesions affecting the central nervous system, in particular an upper motor neuron lesion. Selective dorsal rhizotomy (SDR) is a surgical technique developed to treat spastic diplegia, one of the common forms of cerebral palsy, resulting from the lack of supraspinal inhibitory controls. The aim of SDR is to identify and cut a critical amount of the sensory rootlets, in particular those contributing the most to spasticity, in order to relieve the patient from lower limb spasticity while preserving motor strength and sphincter control. Various surgical techniques to perform SDR have been proposed over time. Similarly, intraoperative neurophysiology (ION)-first introduced by Fasano and colleagues in 1976-is a safe and effective tool to guide the surgeon in the procedure of SDR, but different ION strategies are used by different authors, and the value of ION itself has been questioned. Methods: The purpose of this paper is to review the anatomo-physiological background of SDR, the historical development of the surgical technique, and the essential principles of ION. Results: While some surgeons privilege a single-level approach and others a multi-level approach, nowadays, there are still neither agreement nor guidelines on the percentage of roots to be cut. Rather, a tailored approach based on both the preoperative functional status as well as intraoperative ION findings seems reasonable. ION is considered not essential to decide the percentage of roots to cut, but it assists to distinguish between ventral and dorsal roots, and to preserve sphincterial function, whenever S2 rootlets are included in SDR. Conclusions: To optimize the balance between reduction of spasticity and preservation of motor strength while minimizing the neurological damage remains the main goal of SDR
Chapter 13 - Intraoperative neurophysiology in intramedullary spinal cord tumor surgery
No full textIntramedullary spinal cord tumor (ISCT) surgery is challenged by a significant risk of neurological injury. Indeed, while most ISCT patients arrive to surgery in good neurological condition due to early diagnosis, many experience some degree of postoperative sensorimotor deficit. Thus, intraoperative neuromonitoring (IONM) is invaluable for providing functional information that helps neurosurgeons tailor the surgical strategy to maximize resection while minimizing morbidity. Somatosensory evoked potential (SEP), muscle motor evoked potential (mMEP), and D-wave monitoring are routinely used to continuously assess the functional integrity of the long pathways within the spinal cord. More recently, mapping techniques have been introduced to identify the dorsal columns and the corticospinal tracts. Intraoperative SEP decline is not a sufficient reason to abandon surgery, since SEPs are very sensitive to anesthesia and surgical maneuvers. Yet, a severe proprioceptive deficit may adversely impact daily life, and the value of SEPs should be reconsidered. While mMEPs are good predictors of short-term motor outcome, the D-wave is the strongest predictor of long-term motor outcome, and its preservation during surgery is essential. Mapping techniques are promising but still need validation in large cohorts of patients to determine their impact on clinical outcome. The therapeutic rather than merely diagnostic value of IONM in spine surgery is still debated, but there is emerging evidence that IONM provides an essential adjunct in ISCT surgery
Chapter 9 - Cortical and subcortical brain mapping
No full textThis chapter is describing mapping settings for awake surgery as well as for surgery under general anesthesia. It describes different stimulation paradigms and the value of different stimulation probes. Besides cortical mapping, it focuses on the importance of subcortical brain-mapping techniques. It also discusses distance estimation from the stimulation site to the corticospinal tract
Intraoperative identification of the corticospinal tract and dorsal column of the spinal cord by electrical stimulation.
No full textOBJECTIVES
Anatomical identification of the corticospinal tract (CT) and the dorsal column (DC) of the exposed spinal cord is difficult when anatomical landmarks are distorted by tumour growth. Neurophysiological identification is complicated by the fact that direct stimulation of the DC may result in muscle motor responses due to the centrally activated H-reflex. This study aims to provide a technique for intraoperative neurophysiological differentiation between CT and DC in the exposed spinal cord.
METHODS
Recordings were obtained from 32 consecutive patients undergoing spinal cord tumour surgery from July 2015 to March 2017. A double train stimulation paradigm with an intertrain interval of 60 ms was devised with recording of responses from limb muscles.
RESULTS
In non-spastic patients (55% of cohort) an identical second response was noted following the first CT response, but the second response was absent after DC stimulation. In patients with pre-existing spasticity (45%), CT stimulation again resulted in two identical responses, whereas DC stimulation generated a second response that differed substantially from the first one. The recovery times of interneurons in the spinal cord grey matter were much shorter for the CT than those for the DC. Therefore, when a second stimulus train was applied 60 ms after the first, the CT-fibre interneurons had already recovered ready to generate a second response, whereas the DC interneurons were still in the refractory period.
CONCLUSIONS
Mapping of the spinal cord using double train stimulation allows neurophysiological distinction of CT from DC pathways during spinal cord surgery in patients with and without pre-existing spasticity
Chapter 23 - Continuous dynamic mapping during surgery of large vestibular schwannoma
No full textContinuous dynamic mapping using an electrified surgical suction device might be a valuable additional tool to classical intraoperative neurophysiology methods in surgery of large vestibular schwannomas. It provides real-time feedback indicating the presence of the facial nerve depending on stimulation intensity and may help to avoid accidental injury to the nerve
- …
