Population encoding of observed and actual somatosensations in the human posterior parietal cortex.

Cognition relies on transforming sensory inputs into a generalizable understanding of the world. Mirror neurons have been proposed to underlie this process, mapping visual representations of others' actions and sensations onto neurons that mediate our own, providing a conduit for understanding. However, this theory has limitations.

Intraoperative discovery of a radiographically occult subependymoma obstructing the obex in a patient with a Chiari malformation - A rare case.

Background: Chiari (type I) malformations are typically congenital. Occasionally, however, tonsillar herniation can arise secondary to cerebrospinal fluid leakage, posterior fossa or intraventricular mass lesions, or other etiologies. We present the first-ever case of an intramedullary subependymoma at the cervicomedullary junction associated with vertebral bone abnormalities and an acquired secondary Chiari malformation.

Cervicomedullary junction mature teratoma with pulmonary differentiation and diastematomyelia in an adult - A rare case.

Background: Intradural extramedullary teratomas in the cervical or cervicomedullary region are rare in adults.

Case Description: We report a symptomatic, mature teratoma at the cervicomedullary junction in a 52-year-old Hispanic female who also has a type I diastematomyelia in the thoracolumbar spine. The patient underwent surgical resection of the lesion with the resolution of presenting symptoms.

Future directions in psychiatric neurosurgery: Proceedings of the 2022 American Society for Stereotactic and Functional Neurosurgery meeting on surgical neuromodulation for psychiatric disorders.

Objective: Despite advances in the treatment of psychiatric diseases, currently available therapies do not provide sufficient and durable relief for as many as 30-40% of patients. Neuromodulation, including deep brain stimulation (DBS), has emerged as a potential therapy for persistent disabling disease, however it has not yet gained widespread adoption. In 2016, the American Society for Stereotactic and Functional Neurosurgery (ASSFN) convened a meeting with leaders in the field to discuss a roadmap for the path forward.

Linear accelerator-based radiosurgery for trigeminal neuralgia: comparative outcomes of frame-based and mask-based techniques.

Objective: Precise and accurate targeting is critical to optimize outcomes after stereotactic radiosurgery (SRS) for trigeminal neuralgia (TN). The aim of this study was to compare the outcomes after SRS for TN in which two different techniques were used: mask-based 4-mm cone versus frame-based 5-mm cone.

Methods: The authors performed a retrospective review of patients who underwent SRS for TN at their institution between 1996 and 2019.

Neural encoding of actual and imagined touch within human posterior parietal cortex.

In the human posterior parietal cortex (PPC), single units encode high-dimensional information with representations that enable small populations of neurons to encode many variables relevant to movement planning, execution, cognition, and perception. Here, we test whether a PPC neuronal population previously demonstrated to encode visual and motor information is similarly engaged in the somatosensory domain. We recorded neurons within the PPC of a human clinical trial participant during actual touch presentation and during a tactile imagery task.

The human primary somatosensory cortex encodes imagined movement in the absence of sensory information.

Classical systems neuroscience positions primary sensory areas as early feed-forward processing stations for refining incoming sensory information. This view may oversimplify their role given extensive bi-directional connectivity with multimodal cortical and subcortical regions. Here we show that single units in human primary somatosensory cortex encode imagined reaches in a cognitive motor task, but not other sensory-motor variables such as movement plans or imagined arm position.

Deep Brain Electrode Externalization and Risk of Infection: A Systematic Review and Meta-Analysis.

Background: When evaluating deep brain stimulation (DBS) for newer indications, patients may benefit from trial stimulation prior to permanent implantation or for investigatory purposes. Although several case series have evaluated infectious complications among DBS patients who underwent trials with external hardware, outcomes have been inconsistent.

Objective: To determine whether a period of lead externalization is associated with an increased risk of infection.

Effect of Gene Mutation on Seizures in Surgery for Tuberous Sclerosis Complex.

Background: Tuberous sclerosis complex (TSC) is a rare genetic disorder that commonly leads to drug-resistant epilepsy in affected patients. This study aimed to determine whether the underlying genetic mutation (TSC1 vs. TSC2) predicts seizure outcomes following surgical treatments for epilepsy.

Cognition in Sensorimotor Control: Interfacing With the Posterior Parietal Cortex.

Millions of people worldwide are afflicted with paralysis from a disruption of neural pathways between the brain and the muscles. Because their cortical architecture is often preserved, these patients are able to plan movements despite an inability to execute them. In such people, brain machine interfaces have great potential to restore lost function through neuroprosthetic devices, circumventing dysfunctional corticospinal circuitry.

Contralateral functional reorganization of the speech supplementary motor area following neurosurgical tumor resection.

We evaluated plasticity in speech supplemental motor area (SMA) tissue in two patients using functional magnetic resonance imaging (fMRI), following resection of tumors in or associated with the dominant hemisphere speech SMA. Patient A underwent resection of a anaplastic astrocytoma NOS associated with the left speech SMA, experienced SMA syndrome related mutism postoperatively, but experienced full recovery 14 months later. FMRI performed 32 months after surgery demonstrated a migration of speech SMA to homologous contralateral hemispheric regional tissue.

Microsurgical versus endoscopic transsphenoidal resection for acromegaly: a systematic review of outcomes and complications.

Purpose: The aim of this systematic review is to evaluate the long-term endocrine outcomes and postoperative complications following endoscopic vs. microscopic transsphenoidal resection (TSR) for the treatment of acromegaly.

Methods: A literature review was performed, and studies with at least five patients who underwent TSR for acromegaly, reporting biochemical remission criteria and long-term remission outcomes were included.

Diffusion Tensor Imaging-Based Thalamic Segmentation in Deep Brain Stimulation for Chronic Pain Conditions.

Background/aims: Thalamic deep brain stimulation (DBS) for the treatment of medically refractory pain has largely been abandoned on account of its inconsistent and oftentimes poor efficacy. Our aim here was to use diffusion tensor imaging (DTI)-based segmentation to assess the internal thalamic nuclei of patients who have undergone thalamic DBS for intractable pain and retrospectively correlate lead position with clinical outcome.

Methods: DTI-based segmentation was performed on 5 patients who underwent sensory thalamus DBS for chronic pain.

Radiosurgery for Secondary Trigeminal Neuralgia: Revisiting the Treatment Paradigm.

Background: The mechanisms by which surgery and radiation elicit pain relief in trigeminal neuralgia (TN) secondary to mass lesions vary widely. We aimed to evaluate the outcomes of radiation to the nerve rather than to the lesion in the treatment of secondary TN.

Methods: We retrospectively reviewed all patients who underwent radiation at the University of California, Los Angeles for TN secondary to tumors.

From Mystics to Modern Times: A History of Craniotomy & Religion.

Neurosurgical treatment of diseases dates back to prehistoric times and the trephination of skulls for various maladies. Throughout the evolution of trephination, surgery and religion have been intertwined to varying degrees, a relationship that has caused both stagnation and progress. From its mystical origins in prehistoric times to its scientific progress in ancient Egypt and its resurgence as a well-validated surgical technique in modern times, trephination has been a reflection of the cultural and religious times.

Challenging Diagnosis and Surgical Management of a Symptomatic Sellar Spine.

Background: The sellar spine is a rare, bony growth that typically arises from the dorsum sellae. Few cases have been described in the literature thus far, and most are asymptomatic and incidentally found. We describe the case of a 19-year-old female in whom a sellar spine was noted to be associated with pituitary glandular deformation and symptomatic optic apparatus compression.

Radiosurgical target distance from the root entry zone in the treatment of trigeminal neuralgia.

Purpose: Stereotactic radiosurgery (SRS) provides a noninvasive treatment modality for patients with medically refractory trigeminal neuralgia. The root entry zone (REZ) has been proposed to be an ideal stereotactic target because it is partially composed of centrally produced myelin, conferring a theoretical increased sensitivity to irradiation as well as increased susceptibility to neurovascular conflict, making it the site in which nociceptive signals likely arise. The aim of this study is to determine if there is a statistically and clinically significant difference in pain relief or facial hypesthesia following SRS based on distance of the stereotactic isocenter from REZ.

Long-term outcomes of intradural cervical dorsal root rhizotomy for refractory occipital neuralgia.

OBJECT Occipital neuralgia (ON) causes chronic pain in the cutaneous distribution of the greater and lesser occipital nerves. The long-term efficacy of cervical dorsal root rhizotomy (CDR) in the management of ON has not been well described. The authors reviewed their 14-year experience with CDR to assess pain relief and functional outcomes in patients with medically refractory ON.

The Dynamic Gait Index in Evaluating Patients with Normal Pressure Hydrocephalus for Cerebrospinal Fluid Diversion.

Background: Diagnosing normal pressure hydrocephalus (NPH) remains challenging. Most clinical tests currently used to evaluate suspected NPH patients for shunt surgery are invasive, require inpatient admission, and are not without complications. An objective, noninvasive, and low-cost alternative would be ideal.

Infundibular dilations of the posterior communicating arteries: pathogenesis, anatomical variants, aneurysm formation, and subarachnoid hemorrhage.

Background: Cerebrovascular infundibular dilations (IDs) are triangular-shaped widenings less than 3 mm in diameter, which are most commonly found at the posterior communicating artery (PCoA). The aims of this systematic review are to elucidate the natural histories of IDs, determine their risk of progression to significant pathology, and discuss potential management options.

Methods: A comprehensive literature search of PubMed was used to find all case reports and series relating to cerebral IDs.

Spinal and Nucleus Caudalis Dorsal Root Entry Zone Lesioning for Chronic Pain: Efficacy and Outcomes.

Background: The role for nucleus caudalis (NC) and spinal dorsal root entry zone (DREZ) lesioning in the management of chronic pain emanating from increased electrical activity in the dorsal horn of the spinal cord and brainstem remains largely uncharted.

Methods: All patients who underwent NC and spinal DREZ lesioning by a single surgeon were identified and follow-up was obtained by telephone questionnaires. Patient demographics, surgical details, outcomes, and complications were critically reviewed for all patients identified.

Ommaya reservoir with ventricular catheter placement for chemotherapy with frameless and pinless electromagnetic surgical neuronavigation.

Background: Accuracy in Ommaya reservoir catheter placement is critical to chemotherapy infusion. Most frameless image guidance is light emitting diode (LED) based, requiring a direct line of communication between instrument and tracker, limiting freedom of instrument movement within the surgical field. Electromagnetic neuronavigation may overcome this challenge.

Stereotactic radiosurgery for intracranial dural arteriovenous fistulas: a systematic review.

Object: The goal of this study was to evaluate the obliteration rate of intracranial dural arteriovenous fistulas (DAVFs) in patients treated with stereotactic radiosurgery (SRS), and to compare obliteration rates between cavernous sinus (CS) and noncavernous sinus (NCS) DAVFs, and between DAVFs with and without cortical venous drainage (CVD).

Methods: A systematic literature review was performed using PubMed. The CS DAVFs and the NCS DAVFs were categorized using the Barrow and Borden classification systems, respectively.