Acute intralesional recording in hypothalamic hamartoma: description of 4 cases

Hypothalamic hamartomas (HHs) are intrinsically epileptogenic lesions associated to medically intractable focal epilepsy mainly characterized by gelastic and focal seizures. Intralesional recording with deep electrodes has documented the presence of ictal discharge arising from inside the lesion. Nevertheless interictal and ictal scalp EEG is poorly informative and non-localizing in a great deal of cases. HH disconnection leads to seizure remission in most cases. To describe the intralesional EEG recordings and to compare them with concomitant scalp EEG and with previous cases reported in literature. We reviewed the medical records of 17 children affected by drug-resistant focal epilepsy associated to HH. We recorded intralesional electrical activity during stereo-endoscopic disconnection in three cases and during deep brain stimulation implantation in one. We also correlated it with the simultaneous scalp-EEG recording. Acute intralesional recordings in our cases confirmed the presence of epileptiform abnormalities intermingled with low-voltage activity, mostly on the same side of the HH attachment. Paroxysmal activity recorded inside the HH was always evident. Mapping of HH epileptogenic activity could be useful to confirm the usefulness of disconnection procedure. This should consider on-site recording from the HH and if abnormalities are detected safely proceed to disconnection of the HH.

Towards a functional atlas of human white matter

OBJECTIVES

Although diffusion tensor imaging (DTI) and postmortem dissections improved the knowledge of white matter (WM) anatomy, functional information is lacking. Our aims are: to provide a subcortical atlas of human brain functions; to elucidate the functional roles of different bundles; to provide a probabilistic resection map of WM.

EXPERIMENTAL DESIGN

We studied 130 patients who underwent awake surgery for gliomas (82 left; 48 right) with electrostimulation mapping at cortical and subcortical levels. Different aspects of language, sensori-motor, spatial cognition, and visual functions were monitored. 339 regions of interest (ROIs) including the functional response errors collected during stimulation were co-registered in the MNI space, as well as the resections' areas and residual tumors. Functional response errors and resection areas were matched with DTI and cortical atlases. Subcortical maps for each function and a probability map of resection were computed.

PRINCIPAL OBSERVATIONS

The medial part of dorsal stream (arcuate fasciculus) subserves phonological processing; its lateral part [indirect anterior portion of the superior longitudinal fascicle (SLF)] subserves speech planning. The ventral stream subserves language semantics and matches with the inferior fronto-occipital fascicle. Reading deficits match with the inferior longitudinal fascicle. Anomias match with the indirect posterior portion of the SLF. Frontal WM underpins motor planning and execution. Right parietal WM subserves spatial cognition. Sensori-motor and visual fibers were the most preserved bundles.

CONCLUSIONS

We report the first anatomo-functional atlas of WM connectivity in humans by correlating cognitive data, electrostimulation, and DTI. We provide a valuable tool for cognitive neurosciences and clinical applications.

The course and the anatomo-functional relationships of the optic radiation: a combined study with 'post mortem' dissections and 'in vivo' direct electrical mapping

Even if different dissection, tractographic and connectivity studies provided pure anatomical evidences about the optic radiations (ORs), descriptions of both the anatomical structure and the anatomo-functional relationships of the ORs with the adjacent bundles were not reported. We propose a detailed anatomical and functional study with 'post mortem' dissections and 'in vivo' direct electrical stimulation (DES) of the OR, demonstrating also the relationships with the adjacent eloquent bundles in a neurosurgical 'connectomic' perspective. Six human hemispheres (three left, three right) were dissected after a modified Klingler's preparation. The anatomy of the white matter was analysed according to systematic and topographical surgical perspectives. The anatomical results were correlated to the functional responses collected during three resections of tumours guided by cortico-subcortical DES during awake procedures. We identified two groups of fibres forming the OR. The superior component runs along the lateral wall of the occipital horn, the trigone and the supero-medial wall of the temporal horn. The inferior component covers inferiorly the occipital horn and the trigone, the lateral wall of the temporal horn and arches antero-medially to form the Meyer's Loop. The inferior fronto-occipital fascicle (IFOF) covers completely the superior OR along its entire course, as confirmed by the subcortical DES. The inferior longitudinal fascicle runs in a postero-anterior and inferior direction, covering the superior OR posteriorly and the inferior OR anteriorly. The IFOF identification allows the preservation of the superior OR in the anterior temporal resection, avoiding post-operative complete hemianopia. The identification of the superior OR during the posterior temporal, inferior parietal and occipital resections leads to the preservation of the IFOF and of the eloquent functions it subserves. The accurate knowledge of the OR course and the relationships with the adjacent bundles is crucial to optimize quality of resection and functional outcome.

Pallidotomy for medically refractory status dystonicus in childhood

AIM

Status dystonicus is a rare and potentially fatal condition of continuous and generalized muscle contraction that can complicate dystonia. As status dystonicus is usually refractory to traditional pharmacological therapy, alternative and invasive strategies have been developed, but so far there are no guidelines on status dystonicus management. Pallidotomy has shown good results in status dystonicus treatment.

METHOD

We report indications, surgical strategy, and outcome of bilateral pallidotomy in four pediatric patients (four males; mean age at surgery 11y 5mo) with secondary dystonia, who developed refractory status dystonicus. Pallidotomy was performed in the area corresponding to the mid portion of the globus pallidus internus.

RESULTS

This procedure allowed patients to recover the pre-status dystonicus condition, controlling dystonic postures and movements of trunk and limbs. Moreover oromandibular dystonia, which is resistant to conservative approaches and deep brain stimulation, was significantly reduced. No postoperative complications were registered.

INTERPRETATION

Our study suggests pallidotomy as a feasible treatment in patients with secondary dystonia complicated by status dystonicus.

Anatomo-functional study of the temporo-parieto-occipital region: dissection, tractographic and brain mapping evidence from a neurosurgical perspective

The temporo-parieto-occipital (TPO) junction is a complex brain territory heavily involved in several high-level neurological functions, such as language, visuo-spatial recognition, writing, reading, symbol processing, calculation, self-processing, working memory, musical memory, and face and object recognition. Recent studies indicate that this area is covered by a thick network of white matter (WM) connections, which provide efficient and multimodal integration of information between both local and distant cortical nodes. It is important for neurosurgeons to have good knowledge of the three-dimensional subcortical organisation of this highly connected region to minimise post-operative permanent deficits. The aim of this dissection study was to highlight the subcortical functional anatomy from a topographical surgical perspective. Eight human hemispheres (four left, four right) obtained from four human cadavers were dissected according to Klingler's technique. Proceeding latero-medially, the authors describe the anatomical courses of and the relationships between the main pathways crossing the TPO. The results obtained from dissection were first integrated with diffusion tensor imaging reconstructions and subsequently with functional data obtained from three surgical cases, all resection of infiltrating glial tumours using direct electrical mapping in awake patients. The subcortical limits for performing safe lesionectomies within the TPO region are as follows: within the parietal region, the anterior horizontal part of the superior longitudinal fasciculus and, more deeply, the arcuate fasciculus; dorsally, the vertical projective thalamo-cortical fibres. For lesions located within the temporal and occipital lobes, the resection should be tailored according to the orientation of the horizontal associative pathways (the inferior fronto-occipital fascicle, inferior longitudinal fascicle and optic radiation). The relationships between the WM tracts and the ventricle system were also examined. These results indicate that a detailed anatomo-functional awareness of the WM architecture within the TPO area is mandatory when approaching intrinsic brain lesions to optimise surgical results and to minimise post-operative morbidity.

Lhermitte-Duclos disease. A case report

Lhermitte-Duclos disease is a rare pathologic condition consisting of a dysplastic gangliocytoma of the cerebellum. Its association with phacomatosis and an autosomal dominant neoplastic syndrome, Cowden's syndrome is also known. Modern neuroimaging contributes to a correct diagnosis and pre- and postoperative evaluation. Here we describe the morphologic and metabolic aspects of the disease as shown by conventional MRI, diffusion imaging and spectroscopy in a 31-year-old woman. In addition, the specific neuroradiologic characteristics are presented and discussed in the light of the main pathologic and clinical features, such as hypertrophy of the cerebellar folia associated with white matter atrophy.

Morphological and chemical analysis of a deep brain stimulation electrode explanted from a dystonic patient

Deep brain stimulation is an effective treatment for different types of dystonia; nevertheless dystonic movements could provoke hardware-related complications, including fractures or electrodes displacement. This study focuses on a morphological and structural analysis of a malfunctioning electrode removed from a dystonic patient. In this case, high impedance values and worsening of symptoms were observed. Scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) were performed on the explanted electrode. The qualitative and quantitative data collected from the damaged electrode were compared with a new electrode, used as a control. The SEM analysis of the damaged electrode revealed fissurations and crack-like forms of the outer jacket tubing, degeneration of the internal core and wires stretching. The EDX analysis permitted to appreciate an increase of chemical elements, especially sodium, suggesting an alteration of the electrode-brain interface. This study shows the qualitative and quantitative alterations of a malfunctioning electrode and, to reduce the rate of hardware-related complications, it suggests the development of more reliable polymers.

Early-stage microvascular alterations of a new model of controlled cortical traumatic brain injury: 3D morphological analysis using scanning electron microscopy and corrosion casting

Object

This study was performed to study the microvascular changes that occur during the first 12 hours after traumatic brain injury (TBI) using the corrosion casting technique.

Methods

The authors performed a qualitative and quantitative morphological study of the changes in cerebral vessels at acute (3 hours) and subacute (12 hours) stages after experimental TBI. They used a model of controlled cortical impact (CCI) injury induced by a recently developed electromagnetic device (impactor), focusing their observations mainly on the microvascular alterations responsible for the formation and maintenance of tissue edema and consequent brain swelling during the first hours after TBI. They used corrosion casting, scanning electron microscopy (SEM), light microscopy, and transmission electron microscopy (TEM) to obtain a morphological qualitative map with both 2D and 3D details.

Results

Scanning electron microscopy analysis of vascular casts documented in 3 dimensions the typical injuries occurring after a TBI: subdural, subarachnoid, and intraparenchymal hemorrhages, along with alterations of the morphological characteristics and architecture of both medium-sized and capillary vessels, including ectasia of pial vessels, sphincter constrictions at the origin of the perforating vessels, focal swelling of perforating vessels, widening of intercellular junctions, and some indirect evidence of structural impairment of endothelial cells. All of these vascular alterations were confirmed in 2D analyses using light microscopy and TEM.

Conclusions

The corrosion casting–SEM technique applied to a CCI experimental model proved to be a reliable method for studying the pathophysiology of the vascular alterations occurring at acute and subacute stages after CCI injury. It was also possible to obtain topographical localization of the vascular and cellular events that usually lead to hyperemia, edema, and brain swelling. Moreover, by applying informatic software to anatomical images it was possible to perform quantification and statistical analysis of the observed events.

Involvement of the right inferior longitudinal fascicle in visual hemiagnosia: a brain stimulation mapping study

Neural foundations underlying visual agnosia are poorly understood. The authors present the case of a patient who underwent awake surgery for a right basal temporooccipital low-grade glioma in which direct electrostimulation was used both at the cortical and subcortical level. Brain mapping over the inferior longitudinal fascicle generated contralateral visual hemiagnosia. These original findings are in agreement with recent tractography data that have confirmed the existence of an occipitotemporal pathway connecting occipital visual input to higher-level processing in temporal lobe structures. This is the first report of a true transient visual hemiagnosia elicited through electrostimulation, supporting the crucial role of inferior longitudinal fascicle in visual recognition.

Awake mapping for resection of cavernous angioma and surrounding gliosis in the left dominant hemisphere: surgical technique and functional results: clinical article

OBJECT

Maximal resection of symptomatic cavernous angioma (CA), including its surrounding gliosis if possible, has been recommended to minimize the risk of seizures or (re)bleeding. However, despite recent neurosurgical advances, such extensive CA removal is still a challenge in eloquent areas. The authors report a consecutive series of patients who underwent awake surgery for CA within the left dominant hemisphere in which intraoperative cortical-subcortical electrical stimulation was used.

METHODS

Nine patients harboring a CA that was revealed by seizures in 6 cases and bleeding in 3 cases underwent resection. All CAs were located in the left dominant hemisphere: 3 temporal, 2 insular, 2 parietal, and 2 in the parietotemporal region. Awake mapping was performed in all cases by using intraoperative cortical-subcortical electrical stimulation and ultrasonography (except in 1 insular CA in which a neuronavigation system was used).

RESULTS

Total removal of the CA was achieved in all patients, with identification and preservation of language and sensory-motor structures. In addition, the pericavernomatous gliosis was removed in 7 cases, according to the functional boundaries provided by intraoperative subcortical stimulation. In 2 cases, subcortical mapping revealed eloquent areas within the surrounding gliosis, which was voluntarily avoided. There was no postsurgical permanent deficit, no rebleeding, and no epilepsy in 7 cases (2 patients had rare seizures in the 1st year or two after surgery, and then complete arrest), with a mean follow-up of 28.5 months (range 3-64 months).

CONCLUSIONS

These results suggest that intraoperative cortical-subcortical stimulation in awake patients represents a valuable adjunct to image-guided surgery with the aim of selecting the safer surgical approach for CAs involving eloquent areas. Moreover, such online mapping can be helpful when removing the pericavernomatous gliosis while preserving functional structures, which can persist within the hemosiderin rim. Thus, the authors propose that awake surgery be routinely considered, both to optimize the resection and to improve the quality of life through seizure control and avoidance of (re)bleeding for CAs located in the left dominant hemisphere.

Subcortical surgical anatomy of the lateral frontal region: human white matter dissection and correlations with functional insights provided by intraoperative direct brain stimulation: laboratory investigation

OBJECT

Recent neuroimaging and surgical results support the crucial role of white matter in mediating motor and higher-level processing within the frontal lobe, while suggesting the limited compensatory capacity after damage to subcortical structures. Consequently, an accurate knowledge of the anatomofunctional organization of the pathways running within this region is mandatory for planning safe and effective surgical approaches to different diseases. The aim of this dissection study was to improve the neurosurgeon's awareness of the subcortical anatomofunctional architecture for a lateral approach to the frontal region, to optimize both resection and postoperative outcome.

METHODS

Ten human hemispheres (5 left, 5 right) were dissected according to the Klingler technique. Proceeding lateromedially, the main association and projection tracts as well as the deeper basal structures were identified. The authors describe the anatomy and the relationships among the exposed structures in both a systematic and topographical surgical perspective. Structural results were also correlated to the functional responses obtained during resections of infiltrative frontal tumors guided by direct cortico-subcortical electrostimulation with patients in the awake condition.

RESULTS

The eloquent boundaries crucial for a safe frontal lobectomy or an extensive lesionectomy are as follows: 1) the motor cortex; 2) the pyramidal tract and premotor fibers in the posterior and posteromedial part of the surgical field; 3) the inferior frontooccipital fascicle and the superior longitudinal fascicle posterolaterally; and 4) underneath the inferior frontal gyrus, the head of the caudate nucleus, and the tip of the frontal horn of the lateral ventricle in the depth.

CONCLUSIONS

Optimization of results following brain surgery, especially within the frontal lobe, requires a perfect knowledge of functional anatomy, not only at the cortical level but also with regard to subcortical white matter connectivity.

Ruptured dissecting vertebrobasilar aneurysm in childhood: what is the therapeutic strategy?

BACKGROUND/AIMS

Pediatric aneurysms are rare, accounting for 0.5-4.6% of all intracranial aneurysms. Dissecting vertebrobasilar aneurysms (DVBA) are more frequently observed among children than adults. Cases acutely presenting with subarachnoid hemorrhage need a prompt treatment because of the higher mortality related to untreated cases. Options for an active DVBA management depend on the features of the malformation and include endovascular and surgical approaches.

METHODS

We refer to an 8-year-old healthy female, who presented with a sudden severe headache and vomit, followed by a half-hour loss of consciousness. A CT scan revealed subarachnoid hemorrhage, and brain MR angiography showed a lesion with mass effect on bulbar structures, suggestive of an aneurysm of the vertebrobasilar junction. The intracranial angiography confirmed this diagnosis and showed a relevant revascularization coming from the anterior cerebral circulation.

RESULTS

Endovascular treatment was considered as a suitable option and occlusion of both vertebral arteries, saving the left posterior inferior cerebellar artery, was performed. No neurological deficits appeared after embolization, and the patient was clinically stable at 18 months of follow-up.

CONCLUSION

In the 'stent era', parent vessel deconstruction throughout endovascular balloon or coil occlusion could be considered in patients with a sound collateral circulation and when cerebellar hemisphere and encephalic trunk feeding is not compromised.

Frontal terminations for the inferior fronto-occipital fascicle: anatomical dissection, DTI study and functional considerations on a multi-component bundle

The anatomy and functional role of the inferior fronto-occipital fascicle (IFOF) remain poorly known. We accurately analyze its course and the anatomical distribution of its frontal terminations. We propose a classification of the IFOF in different subcomponents. Ten hemispheres (5 left, 5 right) were dissected with Klingler's technique. In addition to the IFOF dissection, we performed a 4-T diffusion tensor imaging study on a single healthy subject. We identified two layers of IFOF. The first one is superficial and antero-superiorly directed, terminating in the inferior frontal gyrus. The second is deeper and consists of three portions: posterior, middle and anterior. The posterior component terminates in the middle frontal gyrus (MFG) and dorso-lateral prefrontal cortex. The middle component terminates in the MFG and lateral orbito-frontal cortex. The anterior one is directed to the orbito-frontal cortex and frontal pole. In vivo tractography study confirmed these anatomical findings. We suggest that the distribution of IFOF fibers within the frontal lobe corresponds to a fine functional segmentation. IFOF can be considered as a "multi-function" bundle, with each anatomical subcomponent subserving different brain processing. The superficial layer and the posterior component of the deep layer, which connects the occipital extrastriate, temporo-basal and inferior frontal cortices, might subserve semantic processing. The middle component of the deep layer could play a role in a multimodal sensory-motor integration. Finally, the anterior component of the deep layer might be involved in emotional and behavioral aspects.

Brain Hodotopy: From Esoteric Concept to Practical Surgical Applications

BACKGROUND:

The traditional neurosurgical approach to cerebral lesions is based on the classic view of a rigid brain organization in fixed “eloquent” areas. However, this method is brought into discussion by the conceptual and methodological advances in neurosciences that provide a more dynamic representation of the anatomo-functional distribution of the human central nervous system (CNS).

OBJECTIVE AND METHODS:

We review the relevant literature concerning the main features of the modern CNS representation and their implications in neurosurgical practice.

RESULTS:

The CNS is an integrated, wide, plastic network made up of cortical functional epicenters, “topic organization,” connected by both short-local and large-scale white matter fibers, ie, “hodological organization.” According to this model, called hodotopic, brain function results from parallel streams of information dynamically modulated within an interactive, multimodal, and widely distributed circuit. The application of this framework, which can be studied by combining preoperative, intraoperative, and postoperative mapping techniques, enables the neurosurgeon exploration of the individual anatomo-functional architecture, including neurocognitive and emotional aspects. Thus, it is possible to adapt the surgical approach specifically to each patient and to each lesion according to the individual organization. Several experiences demonstrate the possibility of removing regions traditionally considered inoperable without inducing permanent deficits and the potential use of these areas as a safe passage to deeper territories.

CONCLUSION:

We advocate the more systematic integration of a hodotopical view of the CNS to improve the surgical indications and planning for brain lesions, with the goal of optimizing both the extent of resection and functional outcome.

Awake Mapping Optimizes the Extent of Resection for Low-Grade Gliomas in Eloquent Areas

BACKGROUND

Awake craniotomy with intraoperative electrical mapping is a reliable method to minimize the risk of permanent deficit during surgery for low-grade glioma located within eloquent areas classically considered inoperable. However, it could be argued that preservation of functional sites might lead to a lesser degree of tumor removal. To the best of our knowledge, the extent of resection has never been directly compared between traditional and awake procedures.

OBJECTIVE

We report for the first time a series of patients who underwent 2 consecutive surgeries without and with awake mapping.

METHODS

Nine patients underwent surgery for a low-grade glioma in functional sites under general anesthesia in other institutions. The resection was subtotal in 3 cases and partial in 6 cases. There was a postoperative worsening in 3 cases. We performed a second surgery in the awake condition with intraoperative electrostimulation. The resection was performed according to functional boundaries at both the cortical and subcortical levels.

RESULTS

Postoperative magnetic resonance imaging showed that the resection was complete in 5 cases and subtotal in 4 cases (no partial removal) and that it was improved in all cases compared with the first surgery (P = .04). There was no permanent neurological worsening. Three patients improved compared with the presurgical status. All patients returned to normal professional and social lives.

CONCLUSION

Our results demonstrate that awake surgery, known to preserve the quality of life in patients with low-grade glioma, is also able to significantly improve the extent of resection for lesions located in functional regions.

Awake mapping optimizes the extent of resection for low-grade gliomas in eloquent areas

BACKGROUND

Awake craniotomy with intraoperative electrical mapping is a reliable method to minimize the risk of permanent deficit during surgery for low-grade glioma located within eloquent areas classically considered inoperable. However, it could be argued that preservation of functional sites might lead to a lesser degree of tumor removal. To the best of our knowledge, the extent of resection has never been directly compared between traditional and awake procedures.

OBJECTIVE

We report for the first time a series of patients who underwent 2 consecutive surgeries without and with awake mapping.

METHODS

Nine patients underwent surgery for a low-grade glioma in functional sites under general anesthesia in other institutions. The resection was subtotal in 3 cases and partial in 6 cases. There was a postoperative worsening in 3 cases. We performed a second surgery in the awake condition with intraoperative electrostimulation. The resection was performed according to functional boundaries at both the cortical and subcortical levels.

RESULTS

Postoperative magnetic resonance imaging showed that the resection was complete in 5 cases and subtotal in 4 cases (no partial removal) and that it was improved in all cases compared with the first surgery (P = .04). There was no permanent neurological worsening. Three patients improved compared with the presurgical status. All patients returned to normal professional and social lives.

CONCLUSION

Our results demonstrate that awake surgery, known to preserve the quality of life in patients with low-grade glioma, is also able to significantly improve the extent of resection for lesions located in functional regions.