Evaluation of Selective Tibial Neurotomy for the Spastic Foot Treatment Using a Personal Goal-Centered Approach: A 1-Year Cohort Study.

BACKGROUND: Selective tibial neurotomy (STN) has already demonstrated its effectiveness to reduce foot deformities and spasticity, but assessment according to a goal-centered approach is missing. OBJECTIVE: To evaluate the effectiveness of STN associated with a postoperative rehabilitation program for the treatment of the spastic foot, according to a goal-centered approach. METHODS: Interventional study (before-after STN and rehabilitation program) with observational design including consecutive adult patients with spastic foot, who received STN followed by a rehabilitation program, was performed. The primary outcome measure was the achievement of individual goals at the 1-year follow-up using the Goal Attainment Scaling methodology (with T-score). The secondary outcomes measures were the Modified Ashworth Scale and the modified Rankin Score. RESULTS: A total of 104 patients were included. At the 1-year follow-up, 228/252 (90.5%) goals were achieved: 62/252 (24.6%) were achieved as initially expected, 86/252 (34.1%) were achieved better than initially expected, and 80 (31.7%) were achieved much better than initially expected. The mean T-score was significantly increased at the 1-year follow-up (61.5 ± 10.5) compared with the preoperative period (38.1 ± 2.9, P < .00001), and 95/104 (91.3%) patients had a T-score ≥50, meaning that these patients have achieved their goals. At follow-up, spastic deformities were all significantly decreased ( P < .0001), the Modified Ashworth Scale was significantly lower for each muscle targeted ( P < .0001), and the modified Rankin Score was significantly decreased ( P < .0001) allowing the patient population to improve from a moderate to a slight disability status. CONCLUSION: This study showed that STN, associated with a postoperative rehabilitation program, successfully achieve personal goals in patients with spastic foot.

Stimulation of the motor cerebral cortex in chronic neuropathic pain: the role of electrode localization over motor somatotopy.

BACKGROUND: Previous studies have reported the pain-relieving effect of chronic electrical motor cortex stimulation (eMCS) in various types of neuropathic pain. The study aimed to explore the potential relationship between the clinical efficacy of eMCS for the treatment of chronic neuropathic pain and the precise localization of the contacts over the motor cortex somatotopic representation of the painful area. METHODS: A total of 22 patients with neuropathic pain were implanted with eMCS electrodes. Implantation of the electrodes was performed using intraoperative 1) anatomical identification by neuronavigation software using 3D-MRI; 2) monitoring of somesthetic evoked potentials to check the potential reverse over the central sulcus; and 3) electrical stimulations through the dura to identify the motor responses and its somatotopy. Image fusion of postoperative 3D-CT and preoperative MRI images allowed postoperative location of the electrodes. RESULTS: Analgesic effects were obtained in 18 (81.81%) out of 22 patients. Postoperative 3D-CT analysis showed a correspondence between localization of the contacts and the motor cerebral cortex somatotopy in the patients with postoperative good analgesic effects. No correspondence was found between localization of the contacts and the motor cerebral cortex somatotopy in the four patients with no analgesic effects. In three out of these four patients, analgesic effects were obtained after new surgery allowed repositioning of the electrode over the motor cortex somatotopy of the painful area. CONCLUSIONS: The findings of this study suggest that eMCS provides analgesic effects when the stimulated cortex corresponds to the somatotopy of the painful area.

Insular gliomas: a surgical reappraisal based on a systematic review of the literature.

INTRODUCTION: Insular gliomas are heterogeneous lesions whose management presents multiple challenges for their tendency to affect young patients in good neurological and cognitive conditions, their deep anatomic location and proximity with critical functional and vascular structures. The appropriate management of insular gliomas requires a multidisciplinary evidence-centred teamwork grounded on the best anatomic, neurophysiological and oncological knowledge. The present study provides a reappraisal of the management of insular gliomas based on a systematic review of the literature with the aim of guiding clinicians in the management of such tumors. EVIDENCE ACQUISITION: A systematic review of the literature from the Medline, Embase and Cochrane Central databases was performed. From 2006 to 2016, all articles meeting specific inclusion criteria were included. EVIDENCE SYNTHESIS: The present work summarizes the most relevant evidence about insular gliomas management. The anatomy and physiology of the insula, the new WHO 2016 classification and clinico-radiological presentation of insular gliomas are reviewed. Surgical pearls of insular gliomas resection as well as oncologic and functional outcomes after insular gliomas treatment are discussed. CONCLUSIONS: Management of insular gliomas remains challenging despite improvement in surgical and oncological techniques. However, the literature review supports a growing evidence that recent developments in the multidisciplinary care account for constant improvements of survival and quality of life.

Development of the sensorimotor cortex in the human fetus: a morphological description.

Twenty-one human fetal brains from 13 to 28 gestational weeks were studied macroscopically to describe the morphological stages of sulcal and gyral development in the sensorimotor cortex. In particular, the morphological appearance of the pericentral lateral cortex (sensorimotor cortex) and opercula was noted, as well as the vascularization of these regions. The central cerebral sulci were the first macroscopical structures to be identified on the lateral surface of the human cerebral hemisphere. Four chronological stages of sensorimotor cortex development were defined: stage 1: appearance at 18-19 gestational weeks (GWs) of the inferior part of the central cerebral sulcus; stage 2: development of the pericentral lateral regions and the beginning of opercularization at 20-22 GWs; stage 3: development of parietal and temporal cortices and the covering of the postcentral insular region at 24-26 GWs; and finally stage 4: maturation of the central cerebral regions at 27-28 GWs. These observations indicate the concomitance in the initiation of maturation of the pericentral cerebral cortices.

Is Life better after motor cortex stimulation for pain control? Results at long-term and their prediction by preoperative rTMS.

BACKGROUND: A positive effect of motor cortex stimulation (MCS) (defined as subjective estimations of pain relief ≥ 30%) has been reported in 55 - 64% of patients. Repetitive magnetic cortical stimulation (rTMS) is considered a predictor of MCS effect. These figures are, however, mostly based on subjective reports of pain intensity, and have not been confirmed in the long-term. OBJECTIVES: This study assessed long-term pain relief (2 - 9 years) after epidural motor cortex stimulation and its pre-operative prediction by rTMS, using both intensity and Quality of Life (QoL) scales. STUDY DESIGN: Analysis of the long-term evolution of pain patients treated by epidural motor cortex stimulation, and predictive value of preoperative response to rTMS. SETTING: University Neurological Hospital Pain Center. PATIENTS: Twenty patients suffering chronic pharmaco-resistant neuropathic pain. INTERVENTION: All patients received first randomized sham vs. active 20 Hz-rTMS, before being submitted to MCS surgery. MEASUREMENT: Postoperative pain relief was evaluated at 6 months and then up to 9 years post-MCS (average 6.1 ± 2.6 y) using (i) pain numerical rating scores (NRS); (ii) a combined assessment (CPA) including NRS, drug intake, and subjective quality of life; and (iii) a short questionnaire (HowRu) exploring discomfort, distress, disability, and dependence. RESULTS: Pain scores were significantly reduced by active (but not sham) rTMS and by subsequent MCS. Ten out of 20 patients kept a long-term benefit from MCS, both on raw pain scores and on CPA. The CPA results were strictly comparable when obtained by the surgeon or by a third-party on telephonic survey (r = 0.9). CPA scores following rTMS and long-term MCS were significantly associated (Fisher P = 0.02), with 90% positive predictive value and 67% negative predictive value of preoperative rTMS over long-term MCS results. On the HowRu questionnaire, long-term MCS-related improvement concerned "discomfort" (physical pain) and "dependence" (autonomy for daily activities), whereas "disability" (work, home, and leisure activities) and "distress" (anxiety, stress, depression) did not significantly improve. LIMITATIONS: Limited cohort of patients with inhomogeneous pain etiology. Subjectivity of the reported items by the patient after a variable and long delay after surgery. Predictive evaluation based on a single rTMS session compared to chronic MCS. CONCLUSIONS: Half of the patients still retain a significant benefit after 2 - 9 years of continuous MCS, and this can be reasonably predicted by preoperative rTMS. Adding drug intake and QoL estimates to raw pain scores allows a more realistic assessment of long-term benefits and enhance the rTMS predictive value. The aims of this study and its design were approved by the local ethics committee (University Hospitals St Etienne and Lyon, France).

Morphometry and localization of the temporal transverse Heschl's gyrus in magnetic resonance imaging: a guide for cortical stimulation of chronic tinnitus.

PURPOSE: Subjective tinnitus is considered a phantom auditory phenomenon. Recent studies show that electrical or magnetic stimulation of the cortex can alleviate some tinnitus. The usual target of the stimulation is the primary auditory cortex (PAC) on Heschl's gyrus (HG). The objective of this study was to specify the anatomy of HG by magnetic resonance imaging (MRI). METHODS: Cerebral MRI of 60 patients with chronic tinnitus, carried out before neuronavigated repetitive transcranial magnetic stimulation targeting the auditory cortex, were included. 3D-T1 MRI was reformatted in Talairach-Tournoux's stereotactic space, then the following steps were performed: morphometry of HG, localization of the probabilistic center of the PAC (pcPAC) chosen at the junction between the medial third and the lateral two-thirds of HG, relative to external and cortical landmarks, and identification of its coordinates relative to the bicommissural line (AC-PC). RESULTS: In relation to external landmarks, the pcPAC was identified around 5 cm above the root of the helix of the ear in the direction of a point on the vertex located 4 cm behind the coronal suture, for both sides. In Talairach-Tournoux's stereotactic space with the anterior commissure as the origin, the pcPAC coordinates were x = 43, y = -20, z = 6.8 on the right side, and x = -42.5, y = -21.5, and z = 6.5 on the left. Probabilistic maps of the presence of HG pointed to a relative contraction of data in space, despite inter- and intraindividual differences. CONCLUSION: The choice of our stimulation target was established in the middle of the theoretical position of the PAC. MRI allows a reliable identification of the target structure.

Definition of a stereotactic 3-dimensional magnetic resonance imaging template of the human insula.

BACKGROUND: This study proposes a 3-dimensional (3-D) template of the insula in the bicommissural reference system with posterior commissure (PC) as the center of coordinates. OBJECTIVE: Using the bicommissural anterior commissure (AC)-PC reference system, this study aimed to define a template and design a method for the 3-D reconstruction of the human insula that may be used at an individual level during stereotactic surgery. METHODS: Magnetic resonance imaging (MRI)-based morphometric analysis was performed on 100 cerebral cortices with normal insulae based on a 3-step procedure: Step 1: AC-PC reference system-based reconstruction of the insula from the 1-mm thick 3-D T1-weighted MRI slices. Step 2: Digitalization and superposition of the data obtained in the 3 spatial planes. Step 3: Representation of pixels as colors on a scale corresponding to the probability of localization of each insular anatomic component. RESULTS: The morphometric analysis of the insula confirmed our previously reported findings of a more complex shape delimited by 4 peri-insular sulci. A very significant correlation between the coordinates of the main insular structures and the length of AC-PC was demonstrated. This close correlation allowed us to develop a method that allows the 3-D reconstruction of the insula from MRI slices and only requires the localization of AC and PC. This process defines an area deemed to contain insula with 100% probability. CONCLUSION: This 3-D reconstruction of the insula should be useful to improve its localization and other cortical areas and allow the differentiation of insular cortex from opercular cortex.

Anatomofunctional organization of the insular cortex: a study using intracerebral electrical stimulation in epileptic patients.

PURPOSE: Different lines of evidence suggest that the insular cortex has many important functional roles. Direct electrical stimulation (ES) of the human insular cortex during surgical procedures for epilepsy, functional imaging techniques, and lesion studies also occasionally induces clinical responses. METHODS: In this study, we evaluated 25 patients with drug-refractory focal epilepsy by stereotactically implanting at least one electrode into the insular cortex using an oblique approach (transfrontal or transparietal). One hundred twenty-eight insular sites (each situated between two contiguous contacts within the same electrode) were examined within the gyral substructures. We located each stimulation site by fusing preimplantation three-dimensional (3D) magnetic resonance imaging (MRI) images with the postimplantation 3D computed tomography (CT) scans that revealed the electrode contacts. RESULTS: Sixty-seven stimulations induced at least one clinical response. Stimulation from within the insular cortex evoked 83 responses, without evidence of afterdischarge in the insular or extrainsular regions. We classified the principal responses as sensory (paresthesias and localized warm sensations), motor, pain, auditory, oropharyngeal, speech disturbances (including speech arrest and reduced voice intensity) and neurovegetative phenomena, such as facial reddening, generalized sensations of warmth or cold, hypogastric sensations, anxiety attacks, respiratory accelerations, sensations of rotation, and nausea. CONCLUSIONS: These findings may indicate a functional specificity for the insular gyri and show the need for exploring this structure during invasive presurgical evaluation of epileptic patients according to seizure manifestations.

Middle short gyrus of the insula implicated in speech production: intracerebral electric stimulation of patients with epilepsy.

PURPOSE: Different lines of evidence have suggested an involvement of the insular cortex in speech production. These have included results from lesion studies, functional imaging techniques, and electrical stimulation of the human insular cortex during invasive evaluation of epileptic patients. METHODS: We evaluated 25 patients who had drug refractory focal epilepsy with at least one electrode stereotactically implanted in the insular cortex. RESULTS: Eight responses to insular cortex electrical stimulation were reported by five patients as speech arrest (five responses) and a lowering of voice intensity (three responses). CONCLUSIONS: Data from this study implicate the middle short gyrus of the insula in the production of speech and show the importance of intrainsular electrode implantation during invasive pre-resection evaluation by stereo-electroencephalography (SEEG) when speech arrest occurs early in seizure semiology.

Description of sulcal organization of the insular cortex.

PURPOSE: To study the morphology of the gyri and sulci of the insular region. MATERIALS AND METHODS: This study examined 20 formalin-fixed cerebral hemispheres (10 right and 10 left). Observations described: the peri-insular sulci, anatomical variations in the insular sulci and gyri, and the relationships between the central insular sulcus and the central cerebral sulcus and the anatomy of the insular arteries. RESULTS: Each insula had a trapezoid shape, surrounded by four peri-insular sulci (anterior, superior, posterior, and inferior). We differentiated the posterior peri-insular sulcus from the inferior peri-insular sulcus. These two sulci have two different axes separated by a clear angle. The central insular sulcus divides the insula into two parts. The anterior insula includes three short gyri and the anterior insular pole. The posterior insula includes two long gyri and the posterior insular pole. This structure defines two intra-insular opercula. In 60% of cases, the superior extremity of the central insular sulcus is in direct continuity with the inferior extremity of the cerebral central sulcus. The superior branch of the middle cerebral artery supplies the majority of the anterior insular gyri, and the inferior branch supplies the majority of the posterior insular gyri. CONCLUSIONS: This study details the morphology of each insular structure (gyri, sulci and poles), data which could facilitate surgical access to this deep cortical area and assist in future work correlating anatomy with function.

MRI-based definition of a stereotactic two-dimensional template of the human insula.

OBJECTIVE: This study aimed to create a stereotactic two-dimensional description of the human insula based on accurate radiological morphometric studies. METHODS: Seventy-five normal cerebral MRIs were selected and drawings of the insula then obtained from serial sagittal slices. These drawings were digitalized before superimposing the anterior (AC) and posterior (PC) commissures as references. This allowed us to quantify interindividual anatomical variations in a large cohort of subjects. RESULTS: The morphometric analysis of the insula revealed a more complex shape than previously described. This structure is delimited by four peri-insular sulci (anterior, superior, posterior and inferior) instead of the three sulci classically mentioned. Males have a statistically larger surface area than females, according to a correlated index. Precise measurements of the different insular components allowed us to quantify their potential interindividual anatomical variations and to define their average shapes and stereotactic locations. CONCLUSION: These data create a two-dimensional template of the human insula, with regard to the classical AC-PC stereotactic reference system. They furthermore allow us to quantify the probability that a given element of this structure is located at a predefined position. This should be useful in functional neuroimaging studies and in insular surgery for diagnostic and therapeutic goals.

Safety and usefulness of insular depth electrodes implanted via an oblique approach in patients with epilepsy.

OBJECTIVE: This study investigates the feasibility, safety, and usefulness of depth electrodes stereotactically implanted within the insular cortex. METHODS: Thirty patients with suspected insular involvement during epileptic seizure underwent presurgical stereotactic electroencephalographic recordings using 10 to 16 depth electrodes per patient. Among these, one or two electrodes were implanted via an oblique approach to widely sample the insular cortex. RESULTS: Thirty-five insular electrodes were implanted in the 30 patients without morbidity. A total of 226 recording contacts (mean, 7.5 contacts/patient) explored the insular cortex. Stereotactic electroencephalographic recordings of seizures allowed the differentiation into groups: Group 1, 10 patients with no insular involvement; Group 2, 15 patients with secondary insular involvement; and Group 3, five patients with an initial insular involvement. In temporal epilepsy (n = 17), the insula was never involved at the seizure onset but was frequently involved during the seizures (11 out of 17). In frontotemporal or frontal epilepsy, the insula was involved at the onset of seizure in five out of 13 patients. All patients in Groups 1 and 2 underwent surgery, with a seizure-free outcome in 76.2% of patients. In Group 3, only two of the five patients underwent surgery, with a poor outcome. In temporal lobe epilepsy, surgical outcome tended to be better in Group 1 compared with Group 2 in this small series: results were good in 83.3% (Engel I) versus 72.7%. CONCLUSION: Insula can be safely explored with oblique electrodes. In temporal lobe epilepsy, insular involvement does not significantly modify the short-term postoperative outcome. Future larger studies are necessary to clarify the long-term prognostic value of insular spread.

Middle short gyrus of the insula implicated in pain processing.

Different lines of evidence have suggested an involvement of the insular cortex in pain processing. Direct electrical stimulation (ES) of the human insular cortex during surgical procedure sometimes induces painful sensations and painful stimuli induce activation of the insular cortex as shown by functional neuroimaging. Invasive evaluation of epileptic patients by deep brain stereotactically implanted electrodes provides an opportunity to analyze responses induced by ES of the insular cortex in awake and fully conscious patients. For this study, we included 25 patients suffering from drug refractory focal epilepsy with at least one electrode stereotactically implanted in the insular cortex using an oblique approach (transfrontal or transparietal). Out of the 83 responses induced by insular ES, eight (9.6%) were reported by five patients as painful sensations. Four were restricted to the cephalic region and four were felt on the ipsilateral or bilateral upper limbs, the shoulders and the trunk (pinprick sensations). The eight stimulation sites were anatomically localized via image fusion between pre-implantation 3D MRI and post-implantation 3D CT scans revealing the electrode contacts. All sites inducing painful sensations were restricted to the upper portion of the middle short gyrus of the insula. The findings of this study suggest that middle short gyrus is involved in the processing of pain-producing stimuli.