How we do it? The surgical resection of a medial parietal arteriovenous malformation under multimodal imaging technology-guided hybrid operation.

BACKGROUND: This report described the surgical resection of a challenging medial parietal lobe arteriovenous malformation (AVM) using the hybrid operation theater with a multimodal imaging-guided technology. METHOD: A 29-year-old male was admitted to treat a ruptured medial parietal AVM. The deep and diffusive compartment of the nidus was embolized before resection. Preoperatively and intraoperatively, mixed reality technology with multimodality imaging was utilized for surgical planning and navigation. The nidus was totally resected and confirmed by intraoperative angiography. The patient recovered without sequella. CONCLUSION: We hope this report provides new insights into applying multimodal imaging technology-guided hybrid operation for brain AVM.

A Retrospective Study of Parietal Lobe Epilepsy: Functional Anatomy and Surgical Treatment.

Context: Parietal lobe epilepsy (PLE) accounts for approximately 5% of all focal epilepsies worldwide,1 and few PLE patients have undergone epilepsy surgery in the past. With the introduction of functional neuroimaging methods, such as interictal fluorodeoxyglucose-positron emission tomography (FDG-PET), stereotactic electroencephalograms (SEEGs), and high-resolution magnetic resonance imaging (MRI), more patients with intractable neocortical epilepsy have been considered for surgical treatment. Objective: The study intended to characterize the clinical features, aura, and presurgical evaluations of patients with PLE, by investigating their demographic and clinical characteristics, and to evaluate the prognostic value of the four diagnostic modalities-MRI, FDG-PET, scalp EEG, and SEEG-in terms of the localization of epileptogenic area. Design: The research team performed a retrospective analysis of outcomes for PLE patients who underwent resistive brain surgery. Setting: The study took place in the Neurosurgery Department of Epilepsy at the Second Hospital of Hebei Medical University in Shijiazhuang, China. Participants: Participants were 9 PLE patients, 4 males and 5 females, who underwent epilepsy surgery at the hospital between 2017 and 2019. Outcome Measures: The measures included demographic data, seizure data, electroencephalogram (EEG) recordings, magnetic resonance imaging (MRI) of the brain, positron emission tomography (PET), and stereotactic electroencephalogram (SEEG). The pathological findings were reviewed. Results: The five participants who had a PET all had positive results. Eight participants who had parietal lobe lesions had an MRI, and four had a stereotactic electroencephalogram (SEEG) that localized the epileptogenic zone. The interictal scalp EEG recordings for seven participants showed an abnormality, and six participants who had ictal surface EEG recordings showed parietal ictal EEG onset. Conclusions: Surgical excision of epileptogenic foci is the main treatment for drug-resistant PLE. Parietal functional anatomy is the basis for understanding and diagnosing PLE. Aura, semiology, interictal EEG, and PET are an important foundation for evaluation of PLE patients, and the SEEG is the most valuable tool, allowing localization of the epileptogenic zone.

Parietal interhemispheric transfalcine transtentorial approach for posterior incisural space lesions: from the lab to the operative room.

The operative approach to the posterior incisural space is challenging because of its deep location, the surrounding eloquent areas, and the intimate relationship with the deep veins. Several approaches have been proposed to manage the lesions in this region: supratentorial, infratentorial and a combination of them. Brain retraction, injury to the occipital lobe and corpus callosum, and venous bleeding are the principle drawbacks of these routes. We performed anatomical dissection study using 10 embalmed human cadaver specimens injected with colored latex exploring a different route, parietal interhemispheric transfalcine transtentorial (PITT). Then we used a PITT approach on two patients with posterior incisural space (PIS) lesions. The PITT approach led to successful and safe complete removal of PIS lesions in our cases. No complications were reported. The present approach could be a valuable option in case of PIS lesions, especially those associated with downward displacement of the deep venous complex; thanks to the gravity it reduce the complications related to the occipital lobe retraction and manipulation. Moreover, cutting the superior-anterior edge of the tentorium, the sub-tentorial space could be reached.

Stereotactic MRI-guided laser interstitial thermal therapy for extratemporal lobe epilepsy.

OBJECTIVE: Magnetic resonance imaging (MRI)-guided laser interstitial thermal therapy (MRg-LITT) is an alternative to open epilepsy surgery. We assess safety and effectiveness of MRg-LITT for extratemporal lobe epilepsy (ETLE) in patients who are considered less favorable for open resection. METHODS: We retrospectively reviewed sequential cases of patients with focal ETLE who underwent MRg-LITT between 2012 and 2019. Epileptogenic zones were determined from standard clinical and imaging data ± stereoelectroencephalography (SEEG). Standard stereotactic techniques, MRI thermometry, and a commercial laser thermal therapy system were used for ablations. Anatomic MRI was used to calculate ablation volumes. Clinical outcomes were determined longitudinally. RESULTS: Thirty-five patients with mean epilepsy duration of 21.3 ± 12.2 years underwent MRg-LITT for focal ETLE at a mean age 36.4 ± 12.7 years. A mean 2.59 ± 1.45 trajectories per patient were used to obtain ablation volumes of 8.8 ± 7.5 cm3 . Mean follow-up was 27.3 ± 19.5 months. Of 32 patients with >12 months of follow-up, 17 (53%) achieved good outcomes (Engel class I + II) of whom 14 (44%) were Engel class I. Subgroup analysis revealed better outcomes for patients with lesional ETLE than for those who were nonlesional, multifocal, or who had failed prior interventions (P = .02). Of 13 patients showing favorable seizure-onset patterns (localized low voltage fast activity or rhythmic spiking on SEEG) prior to ablation, 9 (69%) achieved good outcomes, whereas only 3 of 11 (27%) who show other slower onset patterns achieved good outcomes. Minor adverse events included six patients with transient sensorimotor neurologic deficits and four patients with asymptomatic hemorrhages along the fiber tract. Major adverse events included one patient with a brain abscess that required stereotactic drainage and one patient with persistent hypothalamic obesity. Three deaths-two seizure-associated and one suicide-were unrelated to surgical procedures. SIGNIFICANCE: MRI-guided laser interstitial thermal therapy (or MRg-LITT) was well-tolerated and yielded good outcomes in a heterogeneous group of ETLE patients. Lesional epilepsy and favorable seizure-onset patterns on SEEG predicted higher likelihoods of success.

Distinctive epileptogenic networks for parietal operculum seizures.

OBJECTIVE: The present study investigated the electroclinical features and epileptogenic networks of parietal operculum seizures (POS) by using stereoelectroencephalography (SEEG) intracerebral recordings. METHODS: Comprehensive presurgical evaluation data of seven patients with drug-resistant epilepsy with POS were analyzed retrospectively. Stereoelectroencephalography-recorded seizures were processed visually and quantitatively by using epileptogenicity mapping (EM), which has been proposed to ergonomically quantify the epileptogenicity of brain structures with a neuroimaging approach. RESULTS: Six patients reported initial somatosensory or viscerosensitive symptoms. Ictal clinical signs comprised frequently nocturnal hypermotor seizures and contralateral focal motor seizures, including tonic, tonic-clonic, or dystonic seizures of the face and limbs. Interictal and ictal scalp EEG provided information regarding lateralization in the majority of patients, but the discharges were widely distributed over perisylvian or "rolandic-like" regions and the vertex. Furthermore, two subgroups of epileptogenic network organization were identified within POS by SEEG, visually and quantitatively, using an EM approach: group 1 (mesial frontal/cingulate networks) was observed in three patients who mainly exhibited hypermotor seizures; group 2 (perisylvian networks) was observed in four patients who mainly exhibited contralateral focal motor seizures. CONCLUSION: This study indicated that POS could be characterized by initial specific somatosensory sensations, followed by either frequently nocturnal hypermotor seizures or contralateral focal motor seizures. The distinctive seizure semiology depended on the organization of two primary epileptogenic networks. This article is part of the Special Issue "Individualized Epilepsy Management: Medicines, Surgery and Beyond.

Cerebral pleomorphic liposarcoma: Clinicopathologic findings.

Pleomorphic liposarcoma is the rarest subtype of liposarcoma. Involvement of the central nervous system by pleomorphic liposarcoma is exceptional. We present a 62-year-old woman with an intraparenchymal mass involving the left frontoparietal lobes. Histologic examination demonstrated a mesenchymal neoplasm with a dense reticulin network and pleomorphic lipoblasts. Immunohistochemical stain for adipophilin highlighted intracytoplasmic vacuoles. MDM2 immunostain was negative. A diagnosis of pleomorphic liposarcoma was made. There was no evidence of an extracranial primary neoplasm by imaging or physical exam. Pleomorphic liposarcoma may rarely present as a solitary intracranial mass, an entity that must be entertained in the differential diagnosis of pleomorphic tumors involving the brain.
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Microsurgical anatomy of the sagittal stratum.

BACKGROUND: The sagittal stratum (SS) is a critical neural crossroad traversed by several white matter tracts that connect multiple areas of the ipsilateral hemisphere. Scant information about the anatomical organization of this structure is available in literature. The goal of this study was to provide a detailed anatomical description of the SS and to discuss the functional implications of the findings when a surgical approach through this structure is planned. METHODS: Five formalin-fixed human brains were dissected under the operating microscope by using the fiber dissection technique originally described by Ludwig and Klingler. RESULTS: The SS is a polygonal crossroad of associational fibers situated deep on the lateral surface of the hemisphere, medial to the arcuate/superior longitudinal fascicle complex, and laterally to the tapetal fibers of the atrium. It is organized in three layers: a superficial layer formed by the middle and inferior longitudinal fascicles, a middle layer corresponding to the inferior fronto-occipital fascicle, and a deep layer formed by the optic radiation, intermingled with fibers of the anterior commissure. It originates posteroinferiorly to the inferior limiting sulcus of the insula, contiguous with the fibers of the temporal stem, and ends into the posterior temporo-occipito-parietal cortex. CONCLUSION: The white matter fiber dissection reveals the tridimensional architecture of the SS and the relationship between its fibers. A detailed understanding of the anatomy of the SS is essential to decrease the operative risks when a surgical approach within this area is undertaken.

The Surgical Treatment of a Large Cortical Atherosclerotic Middle Cerebral Artery Aneurysm Presenting With Parietal Lobe Infarction.

Distal MCA aneurysms are rarely seen in daily neurosurgical practice and they are, more commonly associated with infectious processes. Here, the authors present a 65-year-old, patient who had an atherosclerotic M4 segment located aneurysm. It was confirmed, that the aneurysm was not related with any infectious process. The patient had, presented clinically by a parietal infarction and she had been successfully operated. The neuronavigation system for this particular case aided us for a precise localization of the aneurysm and gave a chance for a smaller craniotomy.

Mapping visuospatial and self-motion perception functions in the left parietal lobe.

Parietal lobe functions include somesthesia, language, calculation, self-motion perception, and visuospatial awareness. In this video, the authors show the intraoperative mapping of a left parietal lobe for a low-grade glioma resection. Standard sensory and language mapping were performed. Interestingly, by using the "Line Bisection" task, subcortical stimulation of the gyrus angularis was repeatedly associated with ipsilateral spatial neglect, often described in the right parietal lobe. In a similar way, subcortical stimulation in a more posterior point elicited episodes of vertigo, probably due to stimulation of the superior longitudinal fasciculus. Both findings were useful to define the functional limit of the resection. The video can be found here: https://youtu.be/qgGDRW_6u0A .

Awake craniotomy for right inferior lobule glioma.

Awake craniotomy is a method usually used for brain tumors near or within language and/or sensorimotor areas. Preservation of these important neurological functions, however, may not be enough for a normal life. The authors present a case of a 45-year-old woman with an inferior parietal lobule low-grade glioma who underwent an awake craniotomy with sensorimotor and spatial cognition mapping. The video can be found here: https://youtu.be/HMA_pZYg3Ms .

Precuneal epilepsy: Clinical features and surgical outcome.

OBJECTIVE: The precuneus is a complex and highly connected structure located in the medial portion of the superior parietal lobule. The clinical presentation of precuneal epilepsy is poorly characterized, mostly because these patients have seldom been distinguished from those with other types of parietal lobe epilepsy. The present study aims to improve the understanding of precuneal epilepsy by detailing its clinical features and surgical outcomes. METHODS: Six previously unreported cases of drug-resistant precuneal epilepsy investigated between 2002 and 2014 were retrospectively studied. Seizure focus was confirmed by presence of a lesion, intracranial monitoring, or post-operative seizure control when applicable. RESULTS: Seizures arising from the precuneus have heterogeneous presentations, including body movement sensation, visual auras, eye movements, vestibular manifestations, and complex motor behaviors. Two patients with an anterior precuneus lesion described body movement sensations whereas two others with a posterior precuneus lesion experienced visual symptoms. Two of the five patients who underwent epilepsy surgery achieved good seizure control (Engel IA). One patient underwent gamma knife surgery with an Engel IV outcome. Surgical complications included contralateral visual field impairment, limb hypoesthesia and hemispatial neglect. One patient developed late-onset epilepsia partialis continua from a Rolandic subdural grid-related contusion. SIGNIFICANCE: In absence of a clear precuneal epileptogenic lesion, recognition of a precuneal focus is challenging. Magnetoencephalography may sometimes localize the generator but invasive EEG remains in well-selected cases necessary to identify the seizure focus. Surgical failures may be explained by the widespread connectivity of the precuneus with distant and adjacent structures. Different ictal manifestations of precuneal epilepsy in this series provide a clinical correlate to the described functional subdivisions of the precuneus.

MEG language lateralization in partial epilepsy using dSPM of auditory event-related fields.

OBJECTIVE: Methods employed to determine hemispheric language dominance using magnetoencephalography (MEG) have differed significantly across studies in the choice of language-task, the nature of the physiological response studied, recording hardware, and source modeling methods. Our goal was to determine whether an analysis based on distributed source modeling can replicate the results of prior studies that have used dipole-modeling of event-related fields (ERFs) generated by an auditory word-recognition task to determine language dominance in patients with epilepsy. METHODS: We analyzed data from 45 adult patients with drug-resistant partial epilepsy who performed an auditory word-recognition task during MEG recording and also completed a language fMRI study as part of their evaluation for epilepsy surgery. Source imaging of auditory ERFs was performed using dynamic statistical parametric mapping (dSPM). Language laterality indices (LIs) were calculated for four regions of interest (ROIs) by counting above-threshold activations within a 300-600ms time window after stimulus onset. Language laterality (LL) classifications based on these LIs were compared to the results from fMRI. RESULTS: The most lateralized MEG responses to language stimuli were observed in a parietal region that included the angular and supramarginal gyri (AngSmg). In this region, using a half-maximal threshold, source activations were left dominant in 32 (71%) patients, right dominant in 8 (18%), and symmetric in 5 patients (11%). The best agreement between MEG and fMRI on the ternary classification of regional language dominance into left, right, or symmetric groups was also found at the AngSmg ROI (69%). This was followed by the whole-hemisphere and temporal ROIs (both 62%). The frontal ROI showed the least agreement with fMRI (51%). Gross discordances between MEG and FMRI findings were disproportionately of the type where MEG favored atypical right-hemispheric language in a patient with right-hemispheric seizure origin (p<0.05 at three of the four ROIs). SIGNIFICANCE: In a parietal region that includes the angular and supramarginal gyri, language laterality estimates based on dSPM of ERFs during auditory word-recognition shows a degree of MEG-fMRI concordance that is comparable to previously published estimates for MEG-Wada concordance using dipole counting methods and the same task. Our data also suggest that MEG language laterality estimates based on this task may be influenced by the laterality of epileptic networks in some patients. This has not been reported previously and deserves further study.

Reconstruction of a Marjolin Ulcer Defect of the Scalp Invading Brain and Causing Brain Abscess Formation Using Free Latissimus Dorsi Flap.

Marjolin ulcers are known as aggressive malignant tumors that mostly arise over chronic wounds and cutaneous scars. Brain abscess is a serious medical condition that requires surgical drainage along with antibiotic treatment. Here, we report a case with a Marjolin ulcer located over the right parietal bone with intracranial abscess formation along with tumor invasion into brain parenchyma. This patient was a 64-year-old man and had a 4 × 4 cm open wound on his scalp from which a purulent discharge was coming. This wound required surgical excision with security margins, resection of bone, evacuation of the cystic cavity, and excision of the walls of the cystic cavity, which were invaded by the tumor. Duraplasty and reconstruction of the defect with a free lattisimus dorsi flap are performed. To the best of our knowledge, the case reported here is unique because of the formation of brain abscess in the background of a long-lasting Marjolin ulcer invading brain parenchyma. It must be remembered that on the background of cutaneous scars located over the scalp, a Marjolin ulcer may develop, and if left untreated, tumor cells may invade even the brain parenchyma. Long-term asymptomatic brain infections may also accompany the given scenario, and complicate differential diagnosis.

Intracranial multiple myeloma may imitate subdural hemorrhage: How to overcome diagnostic limitations and avoid errors in treatment.

BACKGROUND: Although the diagnosis of subdural hematoma is usually straightforward, occasionally it may be erroneous, leading to mistakes in the treatment. For example, leptomeningeal malignancies, even in the absence of bleeding, may clinically and radiologically mimic subdural hemorrhage. OBJECTIVE: To stress the importance of not only intuitive thinking but also in analytic thinking in appropriate and accurate treatment strategies. METHODS AND ILLUSTRATIVE CASE: In this report, the clinical and radiological pitfalls in differentiating malignant leptomeningeal infiltration and subdural hematomas are discussed. A sample case of an intracranial extra-osseous manifestation of a multiple myeloma that is atypical with regard to its location and clinical presentation is presented for illustration. CONCLUSIONS: The variability of intracranial presentation and the wide spectrum of leptomeningeal malignancies necessitate careful preoperative evaluation of the patient's individual history as well as radiological images to avoid misdiagnosis. A clinician who has become familiar with the pitfalls in the differential diagnosis between leptomeningeal infiltrations and subdural hematoma will act more analytically to solve the patient's problems properly and avoid potential complications for the patient.

Seizures with tonic posturing: Semiologic difference between supplementary sensorimotor area (SSMA) origin and extra-SSMA origin.

In seizures with tonic posturing, differentiation of seizures originating in SSMA from seizures originating in cortices other than SSMA and spreading to SSMA has not been previously attempted. Twenty-two patients were studied with intractable focal epilepsy with tonic limb posturing as the most prominent semiology, who underwent resective surgery and obtained favorable postoperative seizure outcomes. These 22 patients were divided into an SSMA group (N = 12) and an extra-SSMA group (N = 10), according to the location of resection. Resection area in the extra-SSMA group was located in the dorsolateral frontal or prefrontal area in four patients, the frontal operculum (insula) in two, the parietal cortex in three, and the temporoparietal cortex in one patient. Video-recorded seizures were carefully reviewed. Tonic posturing characteristics and the presence or absence of accompanying symptoms were compared between groups. Incidence of preservation of consciousness was significantly higher in the SSMA group (p < 0.001). Patients in the SSMA group demonstrated a propensity for having unilateral or bilateral asymmetrical tonic limb posturing. In contrast, patients in the extra-SSMA group had a statistically significantly higher incidence of bilateral symmetrical tonic limb posturing (p < 0.05). These findings may be helpful in identifying seizure origin.

Comparison of the accuracy and proximal shunt failure rate of freehand placement versus intraoperative guidance in parietooccipital ventricular catheter placement.

OBJECTIVE The aim of this paper is to compare the accuracy of the freehand technique versus the use of intraoperative guidance (either ultrasound guidance or frameless stereotaxy) for placement of parietooccipital ventricular catheters and to determine factors associated with reduced proximal shunt failure. METHODS This retrospective cohort study included all patients from 2 institutions who underwent a ventricular cerebrospinal fluid (CSF) shunting procedure in which a new parietooccipital ventricular catheter was placed between January 2005 and December 2013. Data abstracted for each patient included age, sex, method of ventricular catheter placement, side of ventricular catheter placement, Evans ratio, and bifrontal ventricular span. Postoperative radiographic studies were reviewed for accuracy of ventricular catheter placement. Medical records were also reviewed for evidence of shunt failure requiring revision. Standard statistical methods were used for analysis. RESULTS A total of 257 patients were included in the study: 134 from the University of Michigan and 123 from Washington University in St. Louis. Accurate ventricular catheter placement was achieved in 81.2% of cases in which intraoperative guidance was used versus 67.3% when the freehand technique was used. Increasing age reduced the likelihood of accurate catheter placement (OR 0.983, 95% CI 0.971-0.995; p = 0.005), while the use of intraoperative guidance significantly increased the likelihood (OR 2.809, 95% CI 1.406-5.618; p = 0.016). During the study period, 108 patients (42.0%) experienced shunt failure, 79 patients (30.7%) had failure involving the proximal catheter, and 53 patients (20.6%) had distal failure (valve or distal catheter). Increasing age reduced the likelihood of being free from proximal shunt failure (OR 0.983, 95% CI 0.970-0.995; p = 0.008), while both the use of intraoperative guidance (OR 2.385, 95% CI 1.227-5.032; p = 0.011), and accurate ventricular catheter placement (OR 3.424, 95% CI 1.796-6.524; p = 0.009) increased the likelihood. CONCLUSIONS The use of intraoperative guidance during parietooccipital ventricular catheter placement as part of a CSF shunt system significantly increases the likelihood of accurate catheter placement and subsequently reduces the rate of proximal shunt failure.

Gelastic seizures: incidence, clinical and EEG features in adult patients undergoing video-EEG telemetry.

This study aimed to determine clinical features of adult patients with gelastic seizures recorded on video -electroencephalography (EEG) over a 5-year period. We screened video-EEG telemetry reports for the occurrence of the term "gelastic" seizures, and assessed the semiology, EEG features, and duration of those seizures. Gelastic seizures were identified in 19 (0.8%) of 2,446 admissions. The presumed epileptogenic zone was in the hypothalamus in one third of the cases, temporal lobe epilepsy was diagnosed in another third, and the remainder of the cases presenting with gelastic seizures were classified as frontal, parietal lobe epilepsy or remained undetermined or were multifocal. Gelastic seizures were embedded in a semiology, with part of the seizure showing features of automotor seizures. A small proportion of patients underwent epilepsy surgery. Outcome of epilepsy surgery was related to the underlying pathology; two patients with hippocampal sclerosis had good outcomes following temporal lobe resection and one of four patients with hypothalamic hamartomas undergoing gamma knife surgery had a good outcome.

Clipping of bilateral MCA aneurysms and a coiled ACOM aneurysm through a modified lateral supraorbital craniotomy.

We showcase the microsurgical clipping of a left middle cerebral artery (MCA) aneurysm-(B) done through a modified right lateral supraorbital craniotomy, as well as clipping of a previously coiled anterior communicating (ACOM) artery aneurysm-(C) and a bilobed right MCA aneurysm-(A). Splitting of the right sylvian fissure is initially performed following which a subfrontal approach is used to expose and dissect the contralateral sylvian fissure. The left MCA aneurysm is identified and clipped. The ACOM aneurysm is then clipped following multiple clip repositioning based on flow measurements. The right MCA aneurysm is then identified and each lobe is clipped separately. The first picture showcased in this video is a side to side right and left ICA injection in AP projection. In this picture, (A) points to the bilobed right MCA aneurysm, (B) to the left middle cerebral artery (MCA) aneurysm, and (C) to the previously coiled anterior communicating (ACOM) artery aneurysm. The red dotted line shows that both MCA aneurysms lie within the same plane which makes it easier to clip both of them, through one small craniotomy. The video can be found here: http://youtu.be/4cQC7nHsL5I .

Intraoperative functional mapping of calculation in parietal surgery. New insights and clinical implications.

BACKGROUND: Parietal areas play a crucial role in calculation processing. The purpose of this study is to report our experience in the assessment of calculation processing during awake surgery in parietal areas, focusing on clinical implications and new insights provided by this approach. METHODS: We retrospectively reviewed clinical and surgical data of 13 patients who underwent parietal surgery with calculation mapping. Cortical and sub-cortical areas (in 13 and five patients, respectively) involved in single-digit multiplications and additions were identified using bipolar electro-stimulation. RESULTS: Cortical stimulation data showed that the inferior parietal lobule and the intraparietal sulcus were specifically related to calculation in all cases, regardless of the side (100% of cases, in both sides). Conversely, the superior parietal lobule was inconstantly involved in calculation processing (40% of cases in the left and 75% in the right side), whereas the somatosensory area was never involved. Sub-cortical stimulation was able to detect functional areas for calculation in all patients: in 90% of cases the sub-cortical sites positive for calculation were in close anatomical connection with the cortical sites mapping for the same function. The intraoperative preservation (-or damaging-) of functional sites correlated with the absence (- or occurrence-) of post-operative calculation processing impairment. CONCLUSIONS: Our findings support the specificity of the reported technique in the intraoperative identification of sites functional for calculation. Our data show the bilateral involvement of parietal cortex, especially of the inferior lobule, in calculation processing. Furthermore, our study suggests the existence of a sub-cortical pathway specific for calculation, whose better understanding might be crucial for the clinical outcome of patients.

[Granulomatous inflammation in the bed of resected cerebral cavernoma in a child, caused by a hemostatic agent].

OBJECTIVE: The study presents a clinical observation of foreign body granuloma, which is rare productive inflammation, developed on treatment with a hemostatic material upon removal of cerebral cavernoma. MATERIAL AND METHODS: A 4-year-old boy operated on for left parietal lobe cavernoma was diagnosed with a mass lesion during a follow-up MRI examination 4 months after surgery. The patient was re-operated in connection with suspected abscess formation. The pathological tissue was subjected to the histological and immunohistochemical examination. RESULTS: Inflammation was accompanied by the formation of foreign body granulomas, and, in some areas, had immune nature with signs of focal destructive vasculitis, delayed maturation of the granulation tissue, and disturbance of the current organization and encapsulation processes. It is worth noting that granulomatous inflammation around a hemostatic material in the brain has no specific features during introscopy and mimics an abscess or tumor recurrence. CONCLUSION: The use of hemostatic materials upon resection of cerebral cavernous malformations may cause formation of granuloma mimicking disease relapse or abscess in the long term period. To prevent granulomatous inflammation, removal of a hemostatic material, if possible, from the surgical field is recommended when reliable hemostasis is achieved.