Transient Intraluminal Filament Middle Cerebral Artery Occlusion Stroke Model in Rats: A Step-by-Step Guide and Technical Considerations.

OBJECTIVE: Stroke is a leading cause of disability and mortality worldwide. Related research, although already providing significant insights regarding the underlying pathophysiology and potential treatment strategies, has been far from conclusive. Stroke models have been proved of extreme significance for laboratories around the world. In the present report, we have described in detail the most popular to date focal stroke model, the transient intraluminal filament middle cerebral artery occlusion (tifMCAO) model in rats. This model reliably mimics stroke in humans and also approximates endovascular thrombectomy. METHODS: The tifMCAO model was performed using Wistar rats weighing 300-400 g. We have described the surgical technique in a stepwise manner, with figures and/or high-definition video provided for each step. We have also introduced the use of complete arteriotomy of the external carotid artery stump during the procedure. RESULTS: We performed tifMCAO in 65 rats (male and female) involved in various experimental protocols. Although the initial mortality was 48%, practice reduced the rate to 10%. The mean procedural time was 53 minutes (range, 38-85 minutes). In a group of 8 rats ischemia was confirmed in 7 of them, with the stroke induction rate being 87.5%. CONCLUSIONS: The tifMCAO stroke model in rats is the most often used experimental model of focal ischemia because of its clinical relevance. We revisited the procedure and divided it, for instructional purposes, into 15 consecutive and distinct steps.

Deep Brain Stimulation-Related Surgical Site Infections: A Systematic Review and Meta-Analysis.

BACKGROUND: Over the last decades, the increased use of deep brain stimulation (DBS) has raised concerns about the potential adverse health effects of the treatment. Surgical site infections (SSIs) following an elective surgery remain a major challenge for neurosurgeons. Few studies have examined the prevalence and risk factors of DBS-related complications, particularly focusing on SSIs. OBJECTIVES: We systematically searched published literature, up to June 2020, with no language restrictions. MATERIALS AND METHODS: Eligible were studies that examined the prevalence of DBS-related SSIs, as well as studies that examined risk and preventive factors in relation to SSIs. We extracted information on study characteristics, follow-up, exposure and outcome assessment, effect estimate and sample size. Summary odds ratios (sOR) and 95% confidence intervals (CI) were calculated from random-effects meta-analyses; heterogeneity and small-study effects were also assessed. RESULTS: We identified 66 eligible studies that included 12,258 participants from 27 countries. The summary prevalence of SSIs was estimated at 5.0% (95% CI: 4.0%-6.0%) with higher rates for dystonia (6.5%), as well as for newer indications of DBS, such as epilepsy (9.5%), Tourette syndrome (5.9%) and OCD (4.5%). Similar prevalence rates were found between early-onset and late-onset hardware infections. Among risk and preventive factors, the perioperative implementation of intra-wound vancomycin was associated with statistically significantly lower risk of SSIs (sOR: 0.26, 95% CI: 0.09-0.74). Heterogeneity was nonsignificant in most meta-analyses. CONCLUSION: The present study confirms the still high prevalence of SSIs, especially for newer indications of DBS and provides evidence that preventive measures, such as the implementation of topical vancomycin, seem promising in reducing the risk of DBS-related SSIs. Large clinical trials are needed to confirm the efficacy and safety of such measures.

Neuro-inflammatory Sequelae of Minimal Trauma in the Non-traumatized Human Brain: A Microdialysis Study.

Cytokine measurement directly from the brain parenchyma by means of microdialysis has documented the activation of certain procedures in vivo, after brain trauma in humans. However, the intercalation of the micro-catheter insertion with the phenomena triggered by the head trauma renders the assessment of the findings problematic. The present study attempts to elucidate the pure effect of minimal trauma, represented by the insertion of the micro-catheter, on the non-traumatized human brain. Microdialysis catheters were implanted in 12 patients with drug-resistant epilepsy, and subjected to invasive electroencephalography with intracranial electrodes. Samples were collected during the first 5 days of monitoring. The dialysate was analyzed using bead flow cytometry, and the concentrations of interleukin (IL)-1, IL-6, IL-8, IL-10, IL-12, and tumor necrosis factor-α (TNF-α) were measured. The levels of IL-1 and IL-8 were found to be raised until 48 h post-implantation, and thereafter they reached a plateau of presumably baseline values. The temporal profile of the IL-6 variation was different, with the increase being much more prolonged, as its concentration had not returned to baseline levels at the fifth day post-insertion. TNF-α was found to be significantly raised only 2 h after implantation. IL-10 and IL-12 did not have any significant response to micro-trauma. These findings imply that the reaction of the neuro-inflammatory mechanisms of the brain exist even after minimal trauma, and is unexpectedly intense for IL-6. Questions may arise regarding the objectivity of findings attributed by some studies to inflammatory perturbation after head injury.

Telemetric intracranial pressure monitoring: our experience with 22 patients investigated for intracranial hypertension.

INTRODUCTION: We present the application of the Raumedic® P-tel telemetric device that monitors Intracranial Pressure (ICP) over long periods, in 22 patients, with suspected intracranial hypertension. METHODS: A telemetric device (Raumedic®, Neurovent® P-tel) was surgically implanted in 22 patients aged between 21 and 65 years. Among the patients, the inconclusive diagnosis of benign intracranial hypertension was set in 10, the possible diagnosis of postoperative hydrocephalus in 3, and the possible diagnosis of aqueduct stenosis in 2. Additionally, shunt malfunction and Normal Pressure Hydrocephalus (NPH) were investigated in 1 and 3 patients, respectively. Finally, 3 patients presented ventricular dilatation of unknown origin. All the individuals underwent a 3-day ICP recording within the nursing unit. Three more recordings were obtained over a period of 2-6 months at the outpatient base. RESULTS: Analysis of the data excluded the diagnosis of intracranial hypertension in 12 patients. Elevated ICP values were confirmed in 10 patients. Subsequently, 7 of them underwent shunts' implantation, while 2 refused further neurosurgical treatment and 1 was treated with acetazolamide. Additionally, 1 patient who demonstrated normal ICP values, thus confirmed with NPH, underwent VP shunt implantation, while another 2 with similar characteristics refused further surgery. In our series the overall clinical complication rate after P-tel implantation was insignificant. CONCLUSIONS: The telemetric device is safely implanted via a rather simple procedure. In selected patients, it could provide long-term ICP recordings, which are necessary to confirm diagnosis and guide to the appropriate treatment.

Anterior Cervical Discectomy and Fusion combined with thyroid gland surgery, a tailored case and literature review.

BACKGROUND: Nowadays, Anterior Cervical Discectomy and Fusion (ACDF) is considered a routine procedure. However, unexpected difficulties do occasionally arise, especially when anterior neck pathologies or anatomical variations are encountered. In such cases, proactive thinking will allow surgeons to tailor appropriately their approach and eliminate surgical risks. CASE PRESENTATION: We present the case of a 50-year-old male patient suffering from left upper limb radiculopathy that underwent a C7-T1 ACDF combined with a hemithyroidectomy. Excision of the right thyroid lobe was offered to the patient because of a goiter found during the preoperative work-up. Furthermore, the hemithyroidectomy provided a wide surgical field so the ACDF performed without excreting excessive traction to the adjacent neck structures. CONCLUSIONS: The patient had an uncomplicated post-operative. To our knowledge this is the first report of a planned hemithyroidectomy being carried out as the first step towards an ACDF procedure.

Effect of constant-current pallidal deep brain stimulation for primary dystonia on cognition, mood and quality of life: Results from a prospective pilot trial.

OBJECTIVE: Knowledge on the effects of DBS on cognitive functions is limited and no data exists on the effects of constant-current DBS (CC-GPi-DBS), which appears to prevail over constant-voltage stimulation. Our aim was to prospectively assess the effect of Constant-Current-GPi-DBS, using an 8-contact lead, on cognition, mood and quality of life. PATIENTS AND METHODS: Ten patients aged 27-49 underwent prospective neuropsychological assessment using dedicated tests. Various cognitive domains (intelligence, executive functions, memory, attention, visuo-spatial perception, verbal intelligence) as well as emotional state and quality of life were examined preoperatively and 1, 6 and 12 months after continuous constant-current DBS. RESULTS: Patients performed preoperatively below average on information processing speed, phonemic verbal fluency and working memory. At 6-months there was an improvement in phonemic verbal fluency (p < .05), which was retained at 12-months postoperatively (p = .05). Results also showed marginal improvement in the Trail Making-A test (p = .051) and the Stroop colour-word test (p < .05). Despite improvement in Quality of Life (Physical and Mental Component improved by 32.42% and 29.46% respectively), patients showed no discernible change in anxiety and depression status. CONCLUSIONS: CC-GPi-DBS for primary dystonia has no discernible negative impact on cognition and mood. If anything, we noted an improvement of certain cognitive functions.

Spinal synovial cysts. A case series and current treatment options.

Synovial cysts constitute an uncommon degenerative lesion of the spine. They are usually asymptomatic but they may also cause symptoms of variable severity. The authors present three cases of such cysts, two in the lumbar region of a 55-year-old female and a 66 year old female and one in the cervical region of a 56-year-old male patient. All patients presented with radiculopathy. Magnetic Resonance Images revealed a cystic lesion at the L4/5 level in the first case, at L5/S1 level in the second case and at the C7/T1 junction level in the third case. Treatment has been microsurgical resection of all cysts with no post-operative complications and an excellent outcome. A discussion of current management options for this unusual disease is presented and a decision making flow chart is proposed.

Intrathecal Baclofen Therapy for Painful Muscle Spasms in a Patient with Friedreich's Ataxia.

Friedreich's ataxia (FA) is the most frequent hereditary ataxia syndrome, while painful muscle spasms and spasticity have been reported in 11-15% of FA patients. This report describes the successful management of painful spasms in a 65-year-old woman with FA via intrathecal baclofen (ITB) therapy following unsuccessful medical treatments. To our knowledge, this is the third reported case in the literature. Unfortunately, the pathophysiological characteristics of muscle spasms in FA are not well explored and understood while the therapeutic mechanisms of the different treatments are rather vague. Taking into consideration the suggested spinal atrophy in FA, the clinical resemblance of FA and chronic spinal injury muscle spasms, together with the rapid ITB therapy effectiveness in alleviating FA muscle spasms, we attempted to suggest a putative pathophysiological mechanism acting at the spinal level and possibly explained by the presence of independent spinal locomotor systems producing muscle spasms. Specifically, overexcitement of these centers, due to loss of normal regulation from upper CNS levels, may result in the uncontrolled firing of secondary motor neurons and may be the key to producing muscle spasms. However, further research under experimental and clinical settings seems to be necessary.

A giant pseudoaneurysm of the occipital artery.

BACKGROUND: Pseudoaneurysms of the occipital artery (OA) are extremely rare and can occur following head trauma or iatrogenic injury; OA anatomy seems to play a crucial role in their pathogenesis. CASE DESCRIPTION: This report describes the case of a 76-year-old patient with a giant OA pseudoaneurysm secondary to a head injury the patient had sustained 1 month earlier. After radiological confirmation via ultrasonography (US) and computed tomography angiography (CTA), the patient underwent surgery for resection of the lesion. An uneventful postoperative course with no recurrence was confirmed at 1 and 2-month follow-up visits. CONCLUSIONS: Despite their rarity, pseudoaneurysms of the OA should be considered in the differential diagnosis of patients presenting with an occipital pulsatile mass. Prompt management reduces the risk of a serious hemorrhage. In our case, considering the size of the lesion, surgical resection seemed to be the only reasonable option.

Epidemiology of First Epileptic Seizures in the Northern Aegean Island of Lesvos, Greece.

We aimed at establishing the epidemiologic profile of first epileptic seizures (FES) in the Greek island of Lesvos. During a 1-year period (01/06/2010 to 31/05/2011), cases of FES admitted to the Lesvos General Hospital/addressed by general practitioners/private neurologists were prospectively identified. A total of 45 cases (30 males and 15 females; mean age ± SD of 59.4 ± 28.4 and 58.9 ± 26.8 years, respectively), were collected. The FES incidence rate was 52.1 (95% CI 37-67) per 105 persons. Provoked and unprovoked FES had an incidence of, 16.2 and 35.9 cases per 105 persons, respectively. Following age-adjustment to the 2000 US census population, incidence rates of FES (all types combined) were, 40.5 (95% CI 28-56) per 105 persons. Cerebrovascular disease (CVD) was the most prevalent etiologic factor. The present findings indicate a low-ranking incidence of FES in the studied population and highlight CVD as a leading causative factor.

Approaching the Atrium Through the Intraparietal Sulcus: Mapping the Sulcal Morphology and Correlating the Surgical Corridor to Underlying Fiber Tracts.

BACKROUND: Although the operative corridor used during the intraparietal transsulcal approach to the atrium has been previously investigated, most anatomical studies focus on its relationship to the optic radiations. OBJECTIVE: To study the intraparietal sulcus (IPS) morphology and to explore the subcortical anatomy with regard to the surgical trajectory used during the intraparietal transsulcal tranventricular approach. METHODS: Twenty-five adult, formalin fixed, cerebral hemispheres were investigated. Fifteen underwent the Klingler procedure and were dissected in a lateromedial direction using the fiber microdissection technique. The trajectory of the dissection resembled that of real operative settings. The remaining 10 hemispheres were cut along the longitudinal axis of the sulcus in order to correlate its surface anatomy to corresponding parts of the ventricular system. RESULTS: IPS demonstrated an interrupted course in 36% of the specimens while its branching pattern was variable. The sulcus anterior half was found to overly the atrium in all occasions. Four discrete, consecutive white matter layers were identified en route to the atrium, ie, the arcuate fibers, the arcuate segment of the superior longitudinal fasciculus, the corona radiata and tapetum, with the arcuate segment being near to the dissection trajectory. CONCLUSION: Given the angle of brain transgression during the intraparietal approach, we found the optimal dissection area to be the very middle of the sulcus. The IPS-postcentral sulcus meeting point, in contrast to previous thought, proved to risk potential injury to the arcuate segment of the superior longitudinal fasciculus, thus affecting surgical outcome.

Constant-Current Deep Brain Stimulation of the Globus Pallidus Internus in the Treatment of Primary Dystonia by a Novel 8-Contact (Octrode) Lead.

OBJECTIVE: To evaluate bilateral constant-current globus pallidus internus (GPi) deep brain stimulation using an 8-contact lead. METHODS: This prospective, open-label, single-center pilot study of 10 patients assessed the feasibility of delivering bilaterally constant-current GPi deep brain stimulation with a novel 8-channel lead to treat primary dystonia using standard scales as outcome measures. RESULTS: Patients included 4 men and 6 women with a mean age of 35.8 years ± 9.2 (range, 27-49 years). Mean age of onset was 18.5 years ± 9.1 (range, 8-35 years), and mean disease duration was 17.3 years (range, 7-27 years). All had primary dystonia (8 generalized dystonia, 1 segmental dystonia, 1 focal dystonia). The primary variable was determined as 50% reduction in dystonia symptoms from baseline to the 6-month follow-up, as defined by the Burke-Fahn-Marsden Dystonia Rating Scale. Six patients (60.0%) achieved >50% reduction in Burke-Fahn-Marsden Dystonia Rating Scale score and were classified as responders at the 6-month follow-up. Five of these 6 responders (83.3%) sustained that response through the assessment at the end of the first year. Constant-current stimulation was associated with significant improvement in pain and quality of life in all patients. Nearly 84% of the overall improvement occurred by the end of first month after stimulation onset, documenting an early response to treatment. Axial symptoms responded the best. CONCLUSIONS: Constant-current GPi deep brain stimulation proved safe and efficacious for treatment of primary dystonia. Motor scores improved by 54%, mostly within the first month. No phenotype-specific stimulation could be achieved, despite the capability of the new lead to stimulate specific loci within the GPi.

The Insertion of Electrodes in the Brain for Electrophysiological Recording or Chronic Stimulation Is Not Associated With Any Biochemically Detectable Neuronal Injury.

OBJECTIVE: The aim of this study was to evaluate the degree of brain tissue injury that could be potentially induced by the introduction of a) microrecording electrodes, b) macrostimulation electrodes, or c) chronic stimulation electrodes. We aimed to evaluate whether the use of five simultaneous microrecording tracks is associated with any brain injury not detectable by conventional imaging such as CT or MRI. MATERIALS AND METHODS: The study included 61 patients who underwent surgery for implantation of 121 DBS leads. In all cases, five simultaneous tracts were utilized for microelectrode recordings. All patients underwent measurements of serum S-100b at specific time points as follows: a) prior to the operation, and b) intraoperatively at specific stages of the procedure: 1) after opening the burr hole, 2) after the insertion of microrecording electrodes, 3) during macrostimulation, 4) at the end of the operation, and 5) on the first postoperative day. RESULTS: The levels of serum S-100B protein remained within the normal range during the entire period of investigation in all patients with the exception of two cases. In both patients, the procedure was complicated by intraparenchymal hemorrhage visible in neuro-imaging. The first patient developed a small intraparenchymal hemorrhage, visible on the postoperative MRI, with no neurological deficit. The second patient experienced a focal epileptic seizure after the insertion of the right DBS chronic lead and the postoperative CT scan revealed a right frontal lobe hemorrhage. CONCLUSION: These results strongly indicate that the insertion of either multiple recording electrodes or the implantation of chronic electrodes in DBS does not increase the risk of brain hemorrhage or of other intracranial complications, and furthermore it does not cause any biochemically detectable brain tissue damage.

Algorithmic design of a noise-resistant and efficient closed-loop deep brain stimulation system: A computational approach.

Advances in the field of closed-loop neuromodulation call for analysis and modeling approaches capable of confronting challenges related to the complex neuronal response to stimulation and the presence of strong internal and measurement noise in neural recordings. Here we elaborate on the algorithmic aspects of a noise-resistant closed-loop subthalamic nucleus deep brain stimulation system for advanced Parkinson's disease and treatment-refractory obsessive-compulsive disorder, ensuring remarkable performance in terms of both efficiency and selectivity of stimulation, as well as in terms of computational speed. First, we propose an efficient method drawn from dynamical systems theory, for the reliable assessment of significant nonlinear coupling between beta and high-frequency subthalamic neuronal activity, as a biomarker for feedback control. Further, we present a model-based strategy through which optimal parameters of stimulation for minimum energy desynchronizing control of neuronal activity are being identified. The strategy integrates stochastic modeling and derivative-free optimization of neural dynamics based on quadratic modeling. On the basis of numerical simulations, we demonstrate the potential of the presented modeling approach to identify, at a relatively low computational cost, stimulation settings potentially associated with a significantly higher degree of efficiency and selectivity compared with stimulation settings determined post-operatively. Our data reinforce the hypothesis that model-based control strategies are crucial for the design of novel stimulation protocols at the backstage of clinical applications.

Possible common neurological breakdowns for alexithymia and humour appreciation deficit: A case study.

This brief work is an attempt to point to the possible common neurological breakdowns in giving rise to alexithymia, and impaired appreciation of humour. In particular, we present the case of a patient who lost the ability to enjoy humour after the surgical removal of a frontal groove meningioma, although he was still able to detect it, while at the same time was diagnosed with organic alexithymia. Our results indicate that problems in the affective appreciation of humour and in emotionalizing (alexithymic symptoms) may be the result of damage to the ventral-rostral portions of the ACG/mPFC, which prevent the patient from assessing the salience of emotion and motivational information, and generating emotional reactions; as a result he has trouble experiencing emotions, knowing how he and others feel, and enjoy humour.

Efficacy, complications and cost of surgical interventions for idiopathic intracranial hypertension: a systematic review of the literature.

BACKGROUND: To define the efficacy, complication profile and cost of surgical options for treating idiopathic intracranial hypertension (IIH) with respect to the following endpoints: vision and headache improvement, normal CSF pressure restoration, papilloedema resolution, relapse rate, operative complications, cost of intervention and quality of life. METHODS: A systematic review of the surgical treatment of IIH was carried out. Cochrane Library, MEDLINE and EMBASE databases were systematically searched from 1985 to 2014 to identify all relevant manuscripts written in English. Additional studies were identified by searching the references of retrieved papers and relative narrative reviews. RESULTS: Forty-one (41) studies were included (36 case series and 5 case reports), totalling 728 patients. Three hundred forty-one patients were treated with optic nerve sheath fenestration (ONSF), 128 patients with lumboperitoneal shunting (LPS), 72 patients with ventriculoperitoneal shunting (VPS), 155 patients with venous sinus stenting and 32 patients with bariatric surgery. ONSF showed considerable efficacy in vision improvement, while CSF shunting had a superior headache response. Venous sinus stenting demonstrated satisfactory results in both vision and headache improvement along with the best complication profile and low relapse rate, but longer follow-up periods are needed. The complication rate of bariatric surgery was high when compared to other interventions and visual outcomes have not been reported adequately. ONSF had the lowest cost. CONCLUSIONS: No surgical modality proved to be clearly superior to any other in IIH management. However, in certain contexts, a given approach appears more justified. Therefore, a treatment algorithm has been formulated, based on the extracted evidence of this review. The traditional treatment paradigm may need to be re-examined with sinus stenting as a first-line treatment modality.

Preoperative neuropsychological presentation of patients with refractory frontal lobe epilepsy.

BACKGROUND: This study investigated whether certain cognitive deficits are associated with frontal lobe epilepsy (FLE) aiming to contribute with localization data to the preoperative assessment of epilepsy surgery candidates. METHODS: We evaluated 34 patients with refractory FLE, 37 patients with refractory medial temporal lobe epilepsy (MTLE), and 22 healthy individuals in attention, psychomotor speed, motor function, verbal memory span, verbal fluency, response inhibition/interference, concept formation and set shifting, anticipation and planning, global memory. RESULTS: Neuropsychological performances of FLE and MTLE were similar, with the only exception the WCST-number of categories index, measuring mental flexibility, in which MTLE patients performed significantly worse than FLE patients. Left-FLE patients presented more perseverative responding compared to both other patient groups and healthy controls (HCs), while left-MTLE patients showed worse sorting abilities than the other epilepsy groups. CONCLUSIONS: Our findings suggest a weak cognitive differentiation between FLE and MTLE, probably attributed to the intricate nature of fronto-temporal connectivity frequently resulting in overlapping deficits as well as the confounding effects of seizure-related variables. In clinical practice, a highly individualized (idiographic) neuropsychological approach along with the inclusion of concurrent EEG recordings (e.g., interictal coupling) may be of help for neuropsychologists in identifying FLE patients from those with medial temporal pathology presenting frontal dysfunction as a secondary cognitive symptom.

Dominant efficiency of nonregular patterns of subthalamic nucleus deep brain stimulation for Parkinson's disease and obsessive-compulsive disorder in a data-driven computational model.

OBJECTIVE: Almost 30 years after the start of the modern era of deep brain stimulation (DBS), the subthalamic nucleus (STN) still constitutes a standard stimulation target for advanced Parkinson's disease (PD), but the use of STN-DBS is also now supported by level I clinical evidence for treatment-refractory obsessive-compulsive disorder (OCD). Disruption of neural synchronization in the STN has been suggested as one of the possible mechanisms of action of standard and alternative patterns of STN-DBS at a local level. Meanwhile, recent experimental and computational modeling evidence has signified the efficiency of alternative patterns of stimulation; however, no indications exist for treatment-refractory OCD. Here, we comparatively simulate the desynchronizing effect of standard (regular at 130 Hz) versus temporally alternative (in terms of frequency, temporal variability and the existence of bursts or pauses) patterns of STN-DBS for PD and OCD, by means of a stochastic dynamical model and two microelectrode recording (MER) datasets. APPROACH: The stochastic model is fitted to subthalamic MERs acquired during eight surgical interventions for PD and eight surgical interventions for OCD. For each dynamical system simulated, we comparatively assess the invariant density (steady-state phase distribution) as a measure inversely related to the desynchronizing effect yielded by the applied patterns of stimulation. MAIN RESULTS: We demonstrate that high (130 Hz)-and low (80 Hz)-frequency irregular patterns of stimulation, and low-frequency periodic stimulation interrupted by bursts of pulses, yield in both pathologic conditions a significantly stronger desynchronizing effect compared with standard STN-DBS, and distinct alternative patterns of stimulation. In PD, values of the invariant density measure are proven to be optimal at the dorsolateral oscillatory region of the STN including sites with the optimal therapeutic window. SIGNIFICANCE: In addition to providing novel insights into the efficiency of low-frequency nonregular patterns of STN-DBS for advanced PD and treatment-refractory OCD, this work points to a possible correlation of a model-based outcome measure with clinical effectiveness of stimulation and may have significant implications for an energy- and therapeutically-efficient configuration of a closed-loop neuromodulation system.

A Laboratory Manual for Stepwise Cerebral White Matter Fiber Dissection.

OBJECTIVE: White matter fiber dissection is an important method in acquiring a thorough neuroanatomic knowledge for surgical practice. Previous studies have definitely improved our understanding of intrinsic brain anatomy and emphasized on the significance of this technique in modern neurosurgery. However, current literature lacks a complete and concentrated laboratory guide about the entire dissection procedure. Hence, our primary objective is to introduce a detailed laboratory manual for cerebral white matter dissection by highlighting consecutive dissection steps, and to stress important technical comments facilitating this complex procedure. METHODS: Twenty adult, formalin-fixed cerebral hemispheres were included in the study. Ten specimens were dissected in the lateromedial and 10 in the mediolateral direction, respectively, using the fiber dissection technique and the microscope. RESULTS: Eleven and 8 consecutive and distinctive dissection steps are recommended for the lateromedial and mediolateral dissection procedures, respectively. Photographs highlighting various anatomic landmarks accompany every step. Technical recommendations, facilitating the dissection process, are also indicated. CONCLUSIONS: The fiber dissection technique, although complex and time consuming, offers a three-dimensional knowledge of intrinsic brain anatomy and architecture, thus improving both the quality of microneurosurgery and the patient's standard of care. The present anatomic study provides a thorough dissection manual to those who study brain anatomy using this technique.