Methyl palmitate modulates the nicotine-induced increase in basilar arterial blood flow.

Methyl palmitate (MP) is a fatty acid methyl ester. Our recent study indicated that adrenergic nerve-dependent functional sympathetic-sensory nerve interactions were abolished by MP in mesenteric arteries. However, the effect of MP on perivascular nerves and cerebral blood flow remains unclear. In this study, the increase in basilar arterial blood flow (BABF) after the topical application of nicotinic acetylcholine receptor agonists was measured using laser Doppler flowmetry in anesthetized rats. The choline (a selective α7-nicotinic acetylcholine receptor agonist)-induced increase in BABF was abolished by tetrodotoxin (a neurotoxin), NG -nitro-L-arginine (a nonselective NO synthase inhibitor), α-bungarotoxin (a selective α7-nicotinic acetylcholine receptor inhibitor), and chronic sympathetic denervation. In addition, the nicotine (a nicotinic acetylcholine receptor agonist)-induced increase in BABF was inhibited by MP in a concentration-dependent manner. The acetylcholine-induced increase in BABF was not affected by MP. The myography results revealed that nicotine-induced vasorelaxation was significantly inhibited by MP, but was reversed by chelerythrine (a protein kinase C inhibitor). MP-induced vasodilation was significantly greater in BA rings without endothelium compared to those with endothelium. Meanwhile, MP did not affect baseline BABF. Our results indicate that MP acts as a neuromodulator in the cerebral circulation where it activates the PKC pathway and causes a diminished nicotine-induced increase in blood flow in the brainstem, and that the vasorelaxation effect of MP may play a minor role.

Mortality in Patients with Brainstem Cavernous Malformations.

OBJECTIVE: Brainstem cavernous malformations (BSCM)-associated mortality has been reported up to 20% in patients managed conservatively, whereas postoperative mortality rates range from 0 to 1.9%. Our aim was to analyze the actual risk and causes of BSCM-associated mortality in patients managed conservatively and surgically based on our own patient cohort and a systematic literature review. METHODS: Observational, retrospective single-center study encompassing all patients with BSCM that presented to our institution between 2006 and 2018. In addition, a systematic review was performed on all studies encompassing patients with BSCM managed conservatively and surgically. RESULTS: Of 118 patients, 54 were treated conservatively (961.0 person years follow-up in total). No BSCM-associated mortality was observed in our conservatively as well as surgically managed patient cohort. Our systematic literature review and analysis revealed an overall BSCM-associated mortality rate of 2.3% (95% CI: 1.6-3.3) in 22 studies comprising 1,251 patients managed conservatively and of 1.3% (95% CI: 0.9-1.7) in 99 studies comprising 3,275 patients with BSCM treated surgically. CONCLUSION: The BSCM-associated mortality rate in patients managed conservatively is almost as low as in patients treated surgically and much lower than in frequently cited reports, most probably due to the good selection nowadays in regard to surgery.

Blood supply to the corticospinal tract: A pictorial review with application to cranial surgery and stroke.

The corticospinal tract (CST) is the main neural pathway responsible for conducting voluntary motor function in the central nervous system. The CST condenses into fiber bundles as it descends from the frontoparietal cortex, traveling down to terminate at the anterior horn of the spinal cord. The CST is at risk of injury from vascular insult from strokes and during neurosurgical procedures. The aim of this article is to identify and describe the vasculature associated with the CST from the cortex to the medulla. Dissection of cadaveric specimens was carried out in a manner, which exposed and preserved the fiber tracts of the CST, as well as the arterial systems that supply them. At the level of the motor cortex, the CST is supplied by terminal branches of the anterior cerebral artery and middle cerebral artery. The white matter tracts of the corona radiata and internal capsule are supplied by small perforators including the lenticulostriate arteries and branches of the anterior choroidal artery. In the brainstem, the CST is supplied by anterior perforating branches from the basilar and vertebral arteries. The caudal portions of the CST in the medulla are supplied by the anterior spinal artery, which branches from the vertebral arteries. The non-anastomotic nature of the vessel systems of the CST highlights the importance of their preservation during neurosurgical procedures. Anatomical knowledge of the CST is paramount to clinical diagnosis and treatment of heterogeneity of neurodegenerative, neuroinflammatory, cerebrovascular, and skull base tumors.

Application of a 3D-Printed Navigation Mold in Puncture Drainage for Brainstem Hemorrhage.

BACKGROUND: Brainstem hemorrhage is an acute and severe neurosurgical disease. Cerebral hemorrhage is surgically treated via hematoma puncture drainage because of its minimally invasive nature. However, the placement of puncture must be extremely accurate due to the special anatomical location of the brainstem and its physiological functions. The present study aimed to evaluate whether the application of a three-dimensional (3D)-printed navigation mold achieved good outcomes in the surgical treatment of brainstem hemorrhage. MATERIAL AND METHODS: The present study included seven patients (three men and four women aged 40-56 y) who underwent 3D print-assisted hematoma puncture drainage between June 2016 and March 2018 at Binzhou Medical University Hospital. The amount of brainstem hemorrhage was 15-47 mL. We analyzed the basic surgical conditions, deviation distance, and postoperative clinical improvement. RESULTS: In all cases, the operation was completed successfully; no patient died or contracted an infection intraoperatively. The end of the puncture tube was located in the hematoma cavity in all cases. The deviation distance ranged from 2.5 to 7.2, and this distance gradually reduced with improvements in the technique. The hematoma drainage achieved satisfactory postoperative outcomes, with improvements in symptoms such as respiratory failure and hyperthermia. CONCLUSIONS: Use of a 3D-printed navigation mold for puncture drainage of brainstem hemorrhage realized the purpose of individualized and precision medicine, which is important in maintaining the vital signs of patients with severe brainstem hemorrhage.

Early tracheostomy is associated with better prognosis in patients with brainstem hemorrhage.

Brainstem hemorrhage is presumed to be invariably associated with a poor prognosis in people with spontaneous hypertensive cerebral hemorrhage. The optimal timing of tracheostomy placement in brainstem hemorrhage patients, who generally require endotracheal intubation for airway protection, remains uncertain. Our research aim was to analyze the impact of early tracheostomy versus late tracheostomy on brainstem hemorrhage patients related outcomes and prognostic factors at 30 days. We identified early tracheostomy and how it could benefit the patients with brainstem hemorrhage and ameliorate the predictors of functional recovery at 30 days. Data on 136 patients with brainstem hemorrhage and Glasgow Coma Scale score ≤ 8, were retrospectively collected from 2012 to 2019. Patients were divided into the early tracheostomy group and the late tracheostomy group. Patients in the early tracheostomy group had a significantly lower neurosurgical intensive care unit stay (both overall and survival) compared with the late tracheostomy group (15.6 days vs. 19.0 days, P = 0.041, overall and 14.5 vs. 19.5 days, P = 0.023, survival). Also, the good outcomes (modified Rankin Score ≤ 3) were higher in the early tracheostomy group (P = 0.036). Multivariate analysis demonstrated that less hemorrhagic volume, high Glasgow Coma Scale score on admission, young age, and early tracheostomy were significantly associated with a better 30-day functional outcome. In conclusion, an early tracheostomy in patients with brainstem hemorrhage can reduce neurosurgical intensive care unit stay, and in addition to improvements in prognosis at 30 days.

Natural History of Infratentorial Intracerebral Hemorrhages: Two Subgroups with Distinct Presentations and Outcomes.

BACKGROUND/OBJECTIVE: Infratentorial intracerebral hemorrhage (ICH) is associated with worse prognosis than supratentorial ICH; however, infratentorial ICH is often excluded or underrepresented in clinical trials of ICH. We sought to evaluate the natural history of infratentorial ICH stratified by brainstem or cerebellar location using a prospective observational study inclusive of all spontaneous ICH. METHODS: Using a prospective, single center cohort of patients with spontaneous ICH between 2008-2019, we conducted a descriptive analysis of baseline demographics, severity of injury scores, and long-term functional outcomes of infratentorial ICH stratified by cerebellar or brainstem location. RESULTS: Infratentorial ICH occurred in 82 (13%) of 632 patients in our ICH cohort. Among infratentorial ICH, cerebellar ICH occurred in 45 (55%) and brainstem ICH occurred in 37 (45%). Compared to cerebellar ICH, patients with brainstem ICH had significantly worse severity of injury scores, including lower admission Glasgow Coma Scale (median 14 [7.0 - 15.0] versus 4 [3.0 - 8.0], respectively; P < 0.001) and higher ICH Score (median 2 [1.0 - 3.0] versus 3 [2.75 - 4.0], respectively; P =  0.02). Patients with cerebellar ICH were more likely to be discharged home or to acute rehabilitation (OR 4.8, 95% CI 1.8 - 12.8) but there was no difference in in-hospital mortality (OR 0.4, 95% CI 0.1 - 1.1, P =  0.08) or cause of death (P =  0.5). Modified Rankin Scale scores at 3 months were significantly better in patients with cerebellar ICH compared to brainstem ICH (median 3.5 [1.8 - 6.0] versus median 6 [5.0 - 6.0], P =  0.03). CONCLUSIONS: Location of infratentorial ICH is an important determinant of admission severity and clinical outcome in unselected patients with ICH. Patients with cerebellar ICH have less severe symptoms at presentation and more favorable functional outcomes compared to patients with brainstem ICH.

Brainstem iron overload and injury in a rat model of brainstem hemorrhage.

BACKGROUND AND PURPOSE: Brainstem hemorrhage (BSH) is the most devastating subtype of intracerebral hemorrhage (ICH) with the highest mortality ranging from 56 % to 61.2 %. However, there is no effective medical or surgical therapy to improve its outcomes in clinic to date due to lack of understanding of its injury mechanisms. Herein, we explored the brainstem iron overload and injury in a rat model of BSH. METHODS: Neurological scores were examined on day 1, 3, and 7 after modeling, and mortality of the rats was recorded to draft a survival curve. Rats were monitored by MRI using T2 and susceptibility weighted imaging (SWI) before sacrifice for examination of histology and immunofluorescence on day 1, 3, and 7. RESULTS: BSH rats had a high mortality of 56 % and demonstrated the severe neurological deficits mimicking the clinical conditions. SWI showed that the same increasing tendency in change of hypointense area with that in iron deposition by Perls staining from day 1 to 7. Expression of heme oxygenase 1 (HO-1) and generation of reactive oxygen species (ROS) had similar tendency and both peaked on day 3. Neuronal degeneration occurred and stayed elevated from day 1 to 7, while myelin sheath injury was initially observed on day 1 but without significant difference within 7 days. CONCLUSIONS: The time courses of erythrocyte lysis, HO-1 expression, iron deposition and ROS generation are related to each other after BSH. Besides, brainstem injury including neuronal degeneration and myelin damage were observed and discussed.

Increased brainstem perfusion, but no blood-brain barrier disruption, during attacks of migraine with aura.

See Moskowitz (doi:10.1093/brain/awx099) for a scientific commentary on this article.The migraine aura is characterized by transient focal cortical disturbances causing dramatic neurological symptoms that are usually followed by migraine headache. It is currently not understood how the aura symptoms are related to the headache phase of migraine. Animal studies suggest that cortical spreading depression, the likely mechanism of migraine aura, causes disruption of the blood-brain barrier and noxious stimulation of trigeminal afferents leading to activation of brainstem nuclei and triggering of migraine headache. We used the sensitive and validated technique of dynamic contrast-enhanced high-field magnetic resonance imaging to simultaneously investigate blood-brain barrier permeability and tissue perfusion in the brainstem (at the level of the lower pons), visual cortex, and brain areas of the anterior, middle and posterior circulation during spontaneous attacks of migraine with aura. Patients reported to our institution to undergo magnetic resonance imaging during the headache phase after presenting with typical visual aura. Nineteen patients were scanned during attacks and on an attack-free day. The mean time from attack onset to scanning was 7.6 h. We found increased brainstem perfusion bilaterally during migraine with aura attacks. Perfusion also increased in the visual cortex and posterior white matter following migraine aura. We found no increase in blood-brain barrier permeability in any of the investigated regions. There was no correlation between blood-brain barrier permeability, brain perfusion, and time from symptom onset to examination or pain intensity. Our findings demonstrate hyperperfusion in brainstem during the headache phase of migraine with aura, while the blood-brain barrier remains intact during attacks of migraine with aura. These data thus contradict the preclinical hypothesis of cortical spreading depression-induced blood-brain barrier disruption as a possible mechanism linking aura and headache.awx089media15422686892001.

Adult moyamoya disease associated with abundant phosphorylated tau accumulation in the brainstem: Report of a case with autopsy findings.

We report the case of a 72-year-old Japanese woman with moyamoya disease (MMD). She experienced her first intracerebral hemorrhage (ICH) at the age of 32 years, and had nine ICHs and/or intraventricular hemorrhages during the following 40 years. Cerebral angiograms and vascular pathologies at autopsy confirmed that the patient suffered from MMD. Macroscopically, there were brown-colored changes in the subarachnoid space, mainly at the base of the brain and around the cerebellar hemispheres. Microscopically, hemosiderin deposits were observed mainly in the old hemorrhagic lesions and on the surface of the brainstem and cerebellum. Many AT8-immunoreactive neurons and neurites were observed in the pons and midbrain, mainly in the locus ceruleus and reticular formation in the midbrain. Several AT8-immunoreactive neurons and neurites were positive for Gallyas silver staining. A few tiny and short AT8-immunoreactive processes were observed in the molecular, Purkinje cell and granular layers of the cerebellum. There were a few phosphorylated tau accumulations in the cerebrum without senile plaques. Lewy pathologies and transactive response DNA-binding protein 43 kDa proteinopathy were not detected. We suspect that oxidative stress after repeated bleedings with long-term courses in the ventricles and subarachnoid space may accelerate phosphorylated tau accumulation in the brainstem. To our knowledge, this is the first report of MMD with tauopathy in the brainstem.

Bridging veins and veins of the brainstem in microvascular decompression surgery for trigeminal neuralgia and hemifacial spasm.

OBJECTIVE In microvascular decompression surgery for trigeminal neuralgia and hemifacial spasm, the bridging veins are dissected to provide the surgical corridors, and the veins of the brainstem may be mobilized in cases of venous compression. Strategy and technique in dissecting these veins may affect the surgical outcome. The authors investigated solutions for minimizing venous complications and reviewed the outcome for venous decompression. METHODS The authors retrospectively reviewed their surgical series of microvascular decompression for trigeminal neuralgia and hemifacial spasm in patients treated between 2005 and 2017. Surgical strategies included preservation of the superior petrosal vein and its tributaries, thorough dissection of the arachnoid sleeve that enveloped these veins, cutting of the inferior petrosal vein over the lower cranial nerves, and mobilization or cutting of the veins of the brainstem that compressed the nerve roots. The authors summarized the patient characteristics, operative findings, and postoperative outcomes according to the vascular compression types as follows: artery alone, artery and vein, and vein alone. They analyzed the data using chi-square and 1-way ANOVA tests. RESULTS The cohort was composed of 121 patients with trigeminal neuralgia and 205 patients with hemifacial spasm. The superior petrosal vein and its tributaries were preserved with no serious complications in all patients with trigeminal neuralgia. Venous compression alone and arterial and venous compressions were observed in 4% and 22%, respectively, of the patients with trigeminal neuralgia, and in 1% and 2%, respectively, of those with hemifacial spasm (p < 0.0001). In patients with trigeminal neuralgia, 35% of those with artery and venous compressions and 80% of those with venous compression alone had atypical neuralgia (p = 0.015). The surgical cure and recurrence rates of trigeminal neuralgias with venous compression were 60% and 20%, respectively, and with arterial and venous compressions the rates were 92% and 12%, respectively (p < 0.0001, p = 0.04). In patients with hemifacial spasm who had arterial and venous compressions, their recurrence rate was 60%, and that was significantly higher compared to other compression types (p = 0.0008). CONCLUSIONS Dissection of the arachnoid sleeve that envelops the superior petrosal vein may help to reduce venous complications in surgery for trigeminal neuralgia. Venous compression may correlate with worse prognosis even with thorough decompression, in both trigeminal neuralgia and hemifacial spasm.

Response of Cerebral Blood Flow and Blood Pressure to Dynamic Exercise: A Study Using PET.

Dynamic exercise elicits fluctuations in blood pressure (BP) and cerebral blood flow (CBF). This study investigated responses in BP and CBF during cycling exercise and post-exercise hypotension (PEH) using positron emission tomography (PET). CBF was measured using oxygen-15-labeled water (H215O) and PET in 11 human subjects at rest (Rest), at the onset of exercise (Ex1), later in the exercise (Ex2), and during PEH. Global CBF significantly increased by 13% at Ex1 compared with Rest, but was unchanged at Ex2 and during PEH. Compared with at Rest, regional CBF (rCBF) increased at Ex1 (20~42%) in the cerebellar vermis, sensorimotor cortex for the bilateral legs (M1Leg and S1Leg), insular cortex and brain stem, but increased at Ex2 (28~31%) only in the vermis and M1Leg and S1Leg. During PEH, rCBF decreased compared with Rest (8~13%) in the cerebellum, temporal gyrus, piriform lobe, thalamus and pons. The areas showing correlations between rCBF and mean BP during exercise and PEH were consistent with the central autonomic network, including the brain stem, cerebellum, and hypothalamus (R2=0.25-0.64). The present study suggests that higher brain regions are coordinated through reflex centers in the brain stem in order to regulate the cardiovascular response to exercise.

Early Diffusion-Weighted Imaging Brain Stem Score for Acute Basilar Artery Occlusion Treated with Mechanical Thrombectomy.

BACKGROUND: The diffusion-weighted imaging (DWI) brain stem score (BSS) is an easy to use and can predict the clinical outcome of acute basilar artery occlusion (BAO) who underwent endovascular thrombectomy. The purpose of the current study was to validate its performance in Chinese acute BAO patients treated with mechanical thrombectomy. METHODS: Fifty consecutive patients with acute BAO who received early magnetic resonance imaging and treated with mechanical thrombectomy in a single-center were included. Early ischemic damage on DWI was evaluated by applying BSS system. Receiver operating characteristic (ROC) curve analysis was used to evaluate the performance of the score system and multivariate logistic regression analysis was performed to identify predictor of clinical outcome. RESULTS: Favorable outcomes were achieved in 38% patients (19 of 50 patients). Recanalization was successful in 92% patients (46 of 50 patients). Mortality rate was 26% (n = 13/50). In ROC curve analysis, the area under ROC curve of BSS .864 (95% confidence interval [CI], .738-.945) to predict favorable and .769 (95% CI, .628-.877) to predictor mortality. In logistic regression adjusted for age, baseline National Institute of Health Stroke Scale and time to puncture, DWI BSS ≤2 (odds ratio [OR], 12.416; 95% CI, 2.520-61.179; P = .002) and DWI BSS >3 (OR, 7.871; 95% CI, 1.353-45.797; P = .022) were the independent predictor for favorable outcome and mortality at 3 months respectively. CONCLUSIONS: The results of this study suggest that the DWI BSS can be used to predict clinical outcome in patients with acute BAO treated with mechanical thrombectomy at 3 months.

Vascular Anomalies of Posterior Fossa and Their Implications.

Posterior fossa houses very vital and sensitive structures namely midbrain, pons, medulla, and cerebellum. These structures are irrigated by vertebral, posterior inferior cerebellar, anterior inferior cerebellar, and superior cerebellar arteries. Parts of brain located in posterior fossa control important parts of body so any variation pertaining to stenosis, atresia, hypoplasia, fenestration, agenesis, and duplication in the arteries supplying these parts alter the irrigation pattern culminating into various morbid and mortal neurologic disorders. Therefore, a sound understanding and thorough knowledge of posterior circulation vascular variant anatomy builds the foundation for the accurate diagnosis and appropriate management of neurovascular ischemic and hemorrhagic diseases of posterior fossa. To aid in addressing these complex neurologic disorders and neurosurgical treatment to be carried out successfully, updating and consolidating the knowledge of all the variations/insults of these arteries becomes essential. Therefore, review study has been carried out.Literature search was carried out using databases, including Scielo, Scopmed, Medline, PubMed, and Wiley online library. Papers containing original data were selected and secondary references retrieved from bibliographies. Search terms used were posterior fossa, anomalies of vertebral, posterior inferior cerebellar, anterior inferior cerebellar, and superior cerebellar arteries.The study will be of paramount importance to angiographers in interpreting angiographs, neurologists in diagnosis and treatment of neurologic disorders, and neurosurgeons in performing surgery in posterior fossa and craniovertebral region particularly dealing with tumors and vascular malformations.

Flatness of the infratentorial space associated with hemifacial spasm.

BACKGROUND: Whether a difference in morphology of the infratentorial space is associated with hemifacial spasm is not well understood. The aim of this study was to analyze the three-dimensional conformation of the infratentorial space and evaluate any possible contribution of morphological characteristics to the development of neurovascular compression leading to hemifacial spasm. METHODS: We enrolled 25 patients with hemifacial spasm and matched them by age and sex to controls. The extent of the three-dimensional axes and the volume of the infratentorial space were measured using image analysis software for three-dimensional MRI. We evaluated the correlation between a morphological difference in the infratentorial space and changes in vascular configuration in the brain stem. RESULTS: We found no statistical difference in volumetric analyses. The mean aspect ratio on the coronal plane (the ratio of the Z to X extent) of the infratentorial space in patients with hemifacial spasm was significantly lower (p < 0.01) than that in controls, as was the mean aspect ratio on the sagittal plane (the ratio of Z to Y extent, p < 0.01). A smaller sagittal aspect ratio was correlated (p < 0.05) with greater lateral deviation of the basilar artery. CONCLUSIONS: Our results suggest that flatness of the superior-inferior dimension of the infratentorial space is an anatomical feature that characterizes patients with hemifacial spasm. We hypothesize that this unique structural variation may exaggerate the lateral deviation of the vertebrobasilar arteries due to arteriosclerosis and exacerbate the space competition among vessels and cranial nerves.

Neural correlates of temporal summation of second pain in the human brainstem and spinal cord.

Temporal summation of second pain (TSSP) occurs when painful stimuli are presented repetitively (≥ 0.33 Hz) and results from a C-fibre evoked enhancement (or "wind-up") of the dorsal horn neurons. Based on electrophysiological studies in intact animals, windup is considered a purely central phenomenon. With advancements in functional MRI (fMRI), we can now probe the central mechanisms of this pain response in humans. The aim of this study is to characterize the fMRI responses in the healthy human brainstem and spinal cord that correspond to TSSP. Functional MRI of healthy female adults (N = 15) was conducted while brief, repetitive heat pain stimuli were applied to the right thenar eminence (C6 dermatome), and TSSP (0.33 Hz) and control (0.17 Hz) heat pain paradigms were employed. The stimulus intensity was adjusted to each participant's heat pain sensitivity. Data were analyzed by means of a general linear model, and region-of-interest analyses. As predicted, participants demonstrated significant behavioural summation of pain in the TSSP condition. FMRI results identified enhanced activity in the spinal cord dorsal horn at C6 in response to the TSSP condition. Additionally, multiple areas of the brainstem (RVM and PAG) showed greater responses with the TSSP condition. These results suggest that, in humans, increased pain perception in the TSSP condition is reflected by greater responses in the dorsal horn and in regions known to play a role in the descending modulation of pain, which may modulate the spinal cord response.

Susceptibility-weighted imaging of the venous networks around the brain stem.

INTRODUCTION: The venous network of the brainstem is complex and significant. Susceptibility-weighted imaging (SWI) is a practical technique which is sensitive to veins, especially tiny veins. Our purpose of this study was to evaluate the visualization of the venous network of brainstem by using SWI at 3.0 T. METHODS: The occurrence rate of each superficial veins of brainstem was evaluated by using SWI on a 3 T MR imaging system in 60 volunteers. The diameter of the lateral mesencephalic vein and peduncular vein were measured by SWI using the reconstructed mIP images in the sagittal view. And the outflow of the veins of brainstem were studied and described according to the reconstructed images. RESULTS: The median anterior pontomesencephalic vein, median anterior medullary vein, peduncular vein, right vein of the pontomesencephalic sulcus, and right lateral anterior pontomesencephalic vein were detected in all the subjects (100%). The outer diameter of peduncular vein was 1.38 ± 0.26 mm (range 0.8-1.8 mm). The lateral mesencephalic vein was found in 75% of the subjects and the mean outer diameter was 0.81 ± 0.2 mm (range 0.5-1.2 mm). The inner veins of mesencephalon were found by using SWI. CONCLUSION: The venous networks around the brain stem can be visualized by SWI clearly. This result can not only provide data for anatomical study, but also may be available for the surgical planning in the infratentorial region.

Is there a place for microsurgical vascular decompression of the brainstem for apparent essential blood hypertension? a review.

There are anatomical and physiological evidences that the ventrolateral (VL) region of the medulla plays an important role in blood pressure regulation and that dysfunction at this level may generate hypertension (HT). Vascular compression by a megadolicho-artery from the vertebrobasilar arterial system at the root entry/exit zone (REZ) of the glossopharyngeal (IXth) and vagal (Xth) cranial nerves (CNs) and the adjacent VL aspect of the medulla has been postulated as a causal factor for HT from neurogenic origin. The first attempts at microvascular decompression (MVD) of the IX-Xth CNs together with the neighbouring VL brainstem was revealed promising. These surgical attempts, as well as the numerous MRI studies, with the goal to detect and identify likely responsible neurovascular conflicts (NVC), are reviewed. Established criteria for indication of MVD as an aetiological treatment of apparent essential HT are still needed.

[Cervical spinal dural arteriovenous fistula with rapidly progressive brainstem dysfunction due to venous congestion: a case report].

Spinal dural arteriovenous fistulas(S-dAVFs)are rare vascular malformations of the spine. We experienced a case that presented with rapidly progressive brainstem dysfunction due to venous congestion of cervical dAVFs. A 56-year-old man diagnosed with cervical dAVF four years prior presented with gait disturbance and abnormal thermal nociception on his right side. In addition to the high-intensity lesion from the lower pons to the medulla oblongata on T2-weighted magnetic resonance imaging, diffusion-weighted imaging demonstrated cerebral infarction of the left ventrolateral medulla oblongata. Left vertebral angiography revealed that a feeding artery supplied by the radicular artery at the C4 level formed a fistula with the dilated ascending anterior perimedullary vein. We made a diagnosis of venous congestion due to cervical dAVFs. Numbness on the left upper limb occurred five days after the first symptom. Subsequently, hemiparesis on the left upper limb and swallowing disturbance occurred two weeks after the first symptom. The patient underwent surgical ligation of the dilated abnormal vein, with gradual improvement of his symptoms. Myelopathy due to venous congestion of S-dAVFs usually progresses slowly for several years. However, this case report warns about the possibility that some cases of S-dAVF with rapidly exacerbated symptoms may require prompt therapy.

The thalamus and brainstem act as key hubs in alterations of human brain network connectivity induced by mild propofol sedation.

Despite their routine use during surgical procedures, no consensus has yet been reached on the precise mechanisms by which hypnotic anesthetic agents produce their effects. Molecular, animal and human studies have suggested disruption of thalamocortical communication as a key component of anesthetic action at the brain systems level. Here, we used the anesthetic agent, propofol, to modulate consciousness and to evaluate differences in the interactions of remote neural networks during altered consciousness. We investigated the effects of propofol, at a dose that produced mild sedation without loss of consciousness, on spontaneous cerebral activity of 15 healthy volunteers using functional magnetic resonance imaging (fMRI), exploiting oscillations (<0.1 Hz) in blood oxygenation level-dependent signal across functionally connected brain regions. We considered the data as a graph, or complex network of nodes and links, and used eigenvector centrality (EC) to characterize brain network properties. The EC mapping of fMRI data in healthy humans under propofol mild sedation demonstrated a decrease of centrality of the thalamus versus an increase of centrality within the pons of the brainstem, highlighting the important role of these two structures in regulating consciousness. Specifically, the decrease of thalamus centrality results from its disconnection from a widespread set of cortical and subcortical regions, while the increase of brainstem centrality may be a consequence of its increased influence, in the mildly sedated state, over a few highly central cortical regions key to the default mode network such as the posterior and anterior cingulate cortices.

Preoperative assessment of hemifacial spasm by the coronal heavily T2-weighted MR cisternography.

BACKGROUND: Microvascular decompression (MVD) has become a well-established surgical procedure for hemifacial spasm (HFS). Before surgery, it is essential to evaluate any possible deformity of the brainstem and establish the precise location of the offending vessels. In the present study of HFS patients we examined coronal sections taken by heavily T2-weighted MR cisternography in addition to routine axial sections, and assessed the usefulness of these images through comparison with intraoperative findings. METHODS: Eighty patients with HFS underwent preoperative coronal heavily T2-weighted MR cisternography before microvascular decompression surgery. Three neurosurgeons examined the preoperative axial and coronal MR images and evaluated vessel invagination into the brainstem. The usefulness of coronal sections was assessed statistically by the Mann-Whitney U test. RESULTS: Invagination of the offending vessel into the brainstem was observed in 24 cases (30.0%). In 19 patients, it was predicted preoperatively that compression of the flocculus and brainstem would be required in order to approach the offending vessels. Coronal MR cisternography was significantly more useful in cases with vessel invagination into the brainstem than in cases without invagination. CONCLUSIONS: Coronal sections obtained by MR cisternography are able to demonstrate the severity of vessel invagination into the brainstem as well as revealing the presence of the offending vessel. This information is helpful for planning a suitable approach to the root exit zone.