Brainstem toxicity after proton or photon therapy in children and young adults with localized intracranial ependymoma: A French retrospective study

BACKGROUND AND PURPOSE

Ependymoma is the third most frequent childhood braintumor. Standard treatment is surgery followed by radiation therapy including proton therapy (PBT). Retrospective studies have reported higher rates of brainstem injury after PBT than after photon therapy (XRT). We report a national multicenter study of the incidence of brainstem injury after XRT versus PBT, and their correlations with dosimetric data.

MATERIAL AND METHODS

We included all patients aged < 25 years who were treated with PBT or XRT for intracranial ependymoma at five French pediatric oncology reference centers between 2007 and 2020. We reviewed pre-irradiation MRI, follow-up MRIs over the 12 months post-treatment and clinical data.

RESULTS

Of the 83 patients, 42 were treated with PBT, 37 with XRT, and 4 with both (median dose: 59.4 Gy, range: 53‑60). No new or progressive symptomatic brainstem injury was found. Four patients presented asymptomatic radiographic changes (punctiform brainstem enhancement and FLAIR hypersignal), with median onset at 3.5 months (range: 3.0‑9.4) after radiation therapy, and median offset at 7.6 months (range: 3.7‑7.9). Two had been treated with PBT, one with XRT, and one with mixed XRT-PBT. Prescribed doses were 59.4, 55.8, 59.4 and 54 Gy.

CONCLUSION

Asymptomatic radiographic changes occurred in 4.8% of patients with ependymoma in a large national series. There was no correlation with dose or technique. No symptomatic brainstem injury was identified.

Cerebellar somatotopy of the trigemino-cervical complex during nociception

INTRODUCTION

The somatotopic organization of the human cerebellum processes somato-motoric input. Its role during pain perception for nociceptive input remains ambiguous. A standardized experimental trigeminal nociceptive input in functional imaging might clarify the role of the cerebellum in trigeminal nociception. Also of interest is the greater occipital nerve, which innervates the back of the head, and can influence the trigeminal perception due to functional coupling within the brainstem, forming the so-called trigemino-cervical complex.

METHODS

In our preregistered study (clinicaltrials.gov: NTC03999060), we stimulated the greater occipital as well as the three main branches of the trigeminal nerve during functional magnetic resonance imaging in two independent cohorts of young healthy volunteers without psychiatric, neurological or pain-related disorders to disentangle overlapping somatotopic cerebellar organization of the nerves innervating the human head.

RESULTS

We found a dominant effect of the first trigeminal branch in the cerebellum, underpinning its particular role for headache diseases, and somatotopic representations in bilateral cerebellar lobules I-IV, V, VIIb, VIIIa and Crus I as well as in the brainstem.

SIGNIFICANCE

The study expands the current knowledge on facial and head pain processing by the cerebellum and provides an initial somatotopic map of the trigemino-cervical complex in the human cerebellum with a predominant representation of the first trigeminal branch.

Clinicoradiological features of probable chronic lymphocytic inflammation with pontine perivascular enhancement responsive to steroids (CLIPPERS) syndrome

Chronic lymphocytic inflammation with pontine perivascular enhancement responsive to steroids (CLIPPERS) is a recently described chronic inflammatory central nervous system disease. This case report describes a young female patient presenting with weakness in bilateral upper and lower limbs and tinnitus for 2 months. A neurological examination revealed signs of brainstem and cerebellar involvement. MRI brain showed characteristic features of CLIPPERS, with punctate and nodular enhancement in the pons and cerebellum. Differential diagnoses were systematically considered and excluded. The patient showed significant clinical and radiological improvement with steroid therapy. No clinical or radiological red flags occurred during the follow-up. This case underscores the critical role of integrating clinical and radiological findings to effectively diagnose and manage CLIPPERS. It emphasises the importance of ruling out alternative diagnoses through a thorough evaluation.

Uraemic brainstem encephalopathy mimicking ocular myasthenia: a case report

BACKGROUND

Uraemia causes a generalised encephalopathy as its most common neurological complication. Isolated brainstem uraemic encephalopathy is rare. We report a case of fatigable ptosis and complex ophthalmoplegia in brainstem uraemic encephalopathy.

CASE PRESENTATION

A 22-year-old Sri Lankan man with end stage renal failure presented with acute onset diplopia and drooping of eyelids progressively worsening over one week. The patient had not complied with the prescribed renal replacement therapy which was planned to be initiated 5 months previously. On examination, his Glasgow coma scale score was 15/15, He had a fatigable asymmetrical bilateral ptosis. The ice-pack test was negative. There was a complex ophthalmoplegia with bilateral abduction failure and elevation failure of the right eye. The diplopia did not worsen with prolonged stare. The rest of the neurological examination was normal. Serum creatinine on admission was 21.81 mg/dl. The repetitive nerve stimulation did not show a decremental pattern. Magnetic resonance imaging (MRI) of the brain demonstrated diffuse midbrain and pontine oedema with T2 weighted/FLAIR hyperintensities. The patient was haemodialyzed on alternate days and his neurological deficits completely resolved by the end of the second week of dialysis. The follow up brain MRI done two weeks later demonstrated marked improvement of the brainstem oedema with residual T2 weighted/FLAIR hyperintensities in the midbrain.

CONCLUSIONS

Uraemia may rarely cause an isolated brainstem encephalopathy mimicking ocular myasthenia, which resolves with correction of the uraemia.

Quantitative brainstem and spinal MRI in amyotrophic lateral sclerosis: implications for predicting noninvasive ventilation needs

BACKGROUND

Respiratory complications resulting from motor neurons degeneration are the primary cause of death in amyotrophic lateral sclerosis (ALS). Predicting the need for non-invasive ventilation (NIV) in ALS is important for advance care planning and clinical trial design. The aim of this study was to assess the potential of quantitative MRI at the brainstem and spinal cord levels to predict the need for NIV during the first six months after diagnosis.

METHODS

Forty-one ALS patients underwent MRI and spirometry shortly after diagnosis. The need for NIV was monitored according to French health guidelines for 6 months. The performance of four regression models based on: clinical variables, brainstem structures volumes, cervical spinal measurements, and combined variables were compared to predict the need for NIV within this period.

RESULTS

Both the clinical model (R2 = 0.28, AUC = 0.85, AICc = 42.67, BIC = 49.8) and the brainstem structures' volumes model (R2 = 0.30, AUC = 0.85, AICc = 40.13, BIC = 46.99) demonstrated good predictive performance. In addition, cervical spinal cord measurements model similar performance (R2 = 0.338, AUC = 0.87, AICc = 37.99, BIC = 44.49). Notably, the combined model incorporating predictors from all three models yielded the best performance (R2 = 0.60, AUC = 0.959, AICc = 36.38, BIC = 44.8). These findings are supported by observed positive correlations between brainstem volumes, cervical (C4/C7) cross-sectional area, and spirometry-measured lung volumes.

CONCLUSIONS

Our study shows that brainstem volumes and spinal cord area are promising measures to predict respiratory intervention needs in ALS.

Postoperative disappearance of leptomeningeal enhancement around the brainstem in glioblastoma

PURPOSE

Leptomeningeal enhancement (LME) suggests leptomeningeal dissemination (LMD) of tumor cells, which is a complication of end-stage glioblastoma, and is associated with a poor prognosis. However, magnetic resonance imaging (MRI) occasionally indicates the disappearance of peri-brainstem LME after surgical resection of glioblastoma. Since preoperative LMD may affect treatment indications, we aimed to analyze the clinical significance of preoperative LME of the brainstem in glioblastoma.

METHODS

We retrospectively collected clinical and radiological data from consecutive patients with glioblastoma and preoperative LME of the brainstem, who were treated at our hospital between 2017 and 2020.

RESULTS

Among 112 patients with glioblastoma, nine (8%) showed preoperative LME of the brainstem. In comparison with tumors without LME, tumor size was significantly associated with the preoperative LME of the brainstem (p = 0.016). In addition, there was a trend toward significance for a relationship between deep tumor location and preoperative LME of the brainstem (p = 0.058). Notably, among six patients who underwent surgical resection for glioblastoma with LME of the brainstem, four showed significant radiological disappearance of the LME on postoperative MRI. This suggests that the LME did not result from LMD in these cases. Moreover, these four patients lived longer than would be expected from the presence of LMD. However, this LME disappearance was not observed after biopsy or chemoradiotherapy.

CONCLUSIONS

These findings suggest that preoperative LME does not necessarily indicate the presence of untreatable LMD; moreover, LME may disappear after surgical tumor resection. Thus, transient preoperative LME could be attributed to other mechanisms, including impaired venous flow due to intratumoral arteriovenous shunts, which can be resolved by reducing the tumor burden.

Stereotactic Radiosurgery for Vestibular Schwannoma With Radiographic Brainstem Compression

OBJECTIVE

The safety of single-treatment stereotactic radiosurgery (SRS) for vestibular schwannoma (VS) with radiographic evidence of brainstem compression but without motor deficit is controversial. Data on linear accelerator (linac)-based SRS in this setting are scarce. We address this with an outcomes report from an unselected series of patients with VS with radiographic brainstem compression treated with linac SRS.

METHODS

We included 139 patients with unilateral VS (any size) with radiographic brainstem compression (all without serious brainstem neurological deficits). The SRS prescription dose was 12.5 Gy (single fraction) using 6MV linac-produced photon beams, delivered with a multiple arc technique. Inclusion criteria required at least 1 year of radiographic follow-up with magnetic resonance imaging. The primary endpoint was freedom from serious brainstem toxicity (≥grade 3 Common Terminology Criteria for Adverse Events v5); the secondary was freedom from enlargement (tumor progression or any requiring intervention). We assessed serious cranial nerve complications, excluding hearing loss, defined as Common Terminology Criteria for Adverse Events v5 grade 3 toxicity.

RESULTS

Median magnetic resonance imaging follow-up time was 5 years, and median tumor size was 2.5 cm in greatest axial dimension and 5 ml in volume. The median brainstem D0.03 ml=12.6 Gy and median brainstem V10 Gy=0.4 ml. At 5 years, the actuarial freedom from serious brainstem toxicity was 100%, and freedom from tumor enlargement (requiring surgery and/or due to progression) was 90%. Severe facial nerve damage in patients without tumor enlargement was 0.9%.

CONCLUSION

Linac-based SRS, as delivered in our series for VS with radiographic brainstem compression, is safe and effective.

Altered functional connectivity of brainstem nuclei in new daily persistent headache: Evidence from resting-state functional magnetic resonance imaging

OBJECTIVES

The new daily persistent headache (NDPH) is a rare primary headache disorder. However, the underlying mechanisms of NDPH remain incompletely understood. This study aims to apply seed-based analysis to explore the functional connectivity (FC) of brainstem nuclei in patients with NDPH using resting-state functional magnetic resonance imaging (MRI).

METHODS

The FC analysis from the region of interest (ROI) to whole brain voxels was used to investigate 29 patients with NDPH and 37 well-matched healthy controls (HCs) with 3.0 Tesla MRI. The 76 nuclei in the brainstem atlas were defined as ROIs. Furthermore, we explored the correlations between FC and patients' clinical characteristics and neuropsychological evaluations.

RESULTS

Patients with NDPH exhibited reduced FC in multiple brainstem nuclei compared to HCs (including right inferior medullary reticular formation, right mesencephalic reticular formation, bilateral locus coeruleus, bilateral laterodorsal tegmental nucleus-central gray of the rhombencephalon, median raphe, left medial parabrachial nucleus, periaqueductal gray, and bilateral ventral tegmental area-parabrachial pigmented nucleus complex) and increased FC in periaqueductal gray. No significant correlations were found between the FC of these brain regions and clinical characteristics or neuropsychological evaluations after Bonferroni correction (p > 0.00016).

CONCLUSIONS

Our results demonstrated that patients with NDPH have abnormal FC of brainstem nuclei involved in the perception and regulation of pain and emotions.

Partially Reversible FLAIR Hyperintensity Along the Brainstem Surface in Autoimmune Glial Fibrillary Acidic Protein Astrocytopathy

A 41-year-old woman presented with headache, fever, irritability, and confusion. She developed a coma after admission. MRI of the brain revealed periventricular and deep white matter lesions. Fluid-attenuated inversion recovery (FLAIR) and diffusion-weighted imaging hyperintensity along the brainstem surface was observed (Figure 1), considered a rare but characteristic finding in leptomeningeal carcinomatosis from lung cancer.1,2 However, serum tumor markers, CSF cytopathology, contrast-enhanced high-resolution chest CT, and whole-body PET were negative. Antiglial fibrillary acidic protein antibodies (cell-based assay) were positive in serum and CSF. After receiving intravenous methylprednisolone and immunoglobulin, the symptoms improved significantly. Repeated MRI of the brain showed partial resolution of the lesions (Figure 2). The lesions were possibly induced by immune-mediated intramyelinic edema.

Safety and efficacy of the endoscopic transsphenoidal transclival approach performed using direct cortical stimulation for pontine cavernous malformations

OBJECTIVE

Surgical treatment of brainstem cavernous malformations (CMs) is challenging. Surgery using the endoscopic transsphenoidal transclival approach (eTSTCA) is reported as a useful alternative for ventral brainstem CMs. However, CMs located in the ventral midline of the brainstem are rare, and only a small number of case reports on these CMs treated with the eTSTCA exist. The efficacy and safety of the eTSTCA have not yet been fully examined.

METHODS

A retrospective analysis was performed for 5 consecutive patients who underwent surgery via the eTSTCA for treating ventral pontine CMs.

RESULTS

The average maximum CM diameter was 26.0 mm (18-38 mm). All patients underwent MR-diffusion tensor imaging, which confirmed that the corticospinal tract (CST) deviated posteriorly or laterally to the CM. Direct brainstem cortical stimulation was performed to localize the CST before making the cortical incision. After the excision of the CM, the cavity was filled with artificial CSF to make an aqueous surgical field (wet-field technique) for observing the tumor cavity and confirming complete hemostasis and resection. Total removal was achieved in all patients. The preoperative modified Rankin Scale score was 3 in 3 patients and 4 in 2 patients, whereas it was 1 in 2 patients and 0 in 3 patients 3 months after surgery. Postoperative CSF leakage was observed in 1 patient, and transient abducens nerve palsy was observed in 1 patient. No other intra- or postoperative complications were observed.

CONCLUSIONS

MR-diffusion tensor imaging and direct brainstem cortical stimulation were useful to ascertain the proximity of the CST to the CM. The endoscope provides a clear view even underwater, and it was safe and effective to observe the entire CM cavity and confirm complete hemostasis without additional retraction of the brainstem parenchyma, including the CST. The eTSTCA provides a direct access point to the lesion and may be a safer alternative treatment for patients whose CST deviates laterally or posteriorly to the CM.

Brainstem processing of cough sensory inputs in chronic cough hypersensitivity

BACKGROUND

Chronic cough is a prevalent and difficult to treat condition often accompanied by cough hypersensitivity, characterised by cough triggered from exposure to low level sensory stimuli. The mechanisms underlying cough hypersensitivity may involve alterations in airway sensory nerve responsivity to tussive stimuli which would be accompanied by alterations in stimulus-induced brainstem activation, measurable with functional magnetic resonance imaging (fMRI).

METHODS

We investigated brainstem responses during inhalation of capsaicin and adenosine triphosphate (ATP) in 29 participants with chronic cough and 29 age- and sex-matched controls. Psychophysical testing was performed to evaluate individual sensitivities to inhaled stimuli and fMRI was used to compare neural activation in participants with cough and control participants while inhaling stimulus concentrations that evoked equivalent levels of urge-to-cough sensation.

FINDINGS

Participants with chronic cough were significantly more sensitive to inhaled capsaicin and ATP and showed a change in relationship between urge-to-cough perception and cough induction. When urge-to-cough levels were matched, participants with chronic cough displayed significantly less neural activation in medullary regions known to integrate airway sensory inputs. By contrast, neural activations did not differ significantly between the two groups in cortical brain regions known to encode cough sensations whereas activation in a midbrain region of participants with chronic cough was significantly increased compared to controls.

INTERPRETATION

Cough hypersensitivity in some patients may occur in brain circuits above the level of the medulla, perhaps involving midbrain regions that amplify ascending sensory signals or change the efficacy of central inhibitory control systems that ordinarily serve to filter sensory inputs.

FUNDING

Supported in part by a research grant from Investigator-Initiated Studies Program of Merck Sharp & Dohme Pty Ltd. The opinions expressed in this paper are those of the authors and do not necessarily represent those of Merck Sharp & Dohme (Australia) Pty Ltd.

Role of autonomic, nociceptive, and limbic brainstem nuclei in core autism features

Although multiple theories have speculated about the brainstem reticular formation's involvement in autistic behaviors, the in vivo imaging of brainstem nuclei needed to test these theories has proven technologically challenging. Using methods to improve brainstem imaging in children, this study set out to elucidate the role of the autonomic, nociceptive, and limbic brainstem nuclei in the autism features of 145 children (74 autistic children, 6.0-10.9 years). Participants completed an assessment of core autism features and diffusion- and T1-weighted imaging optimized to improve brainstem images. After data reduction via principal component analysis, correlational analyses examined associations among autism features and the microstructural properties of brainstem clusters. Independent replication was performed in 43 adolescents (24 autistic, 13.0-17.9 years). We found specific nuclei, most robustly the parvicellular reticular formation-alpha (PCRtA) and to a lesser degree the lateral parabrachial nucleus (LPB) and ventral tegmental parabrachial pigmented complex (VTA-PBP), to be associated with autism features. The PCRtA and some of the LPB associations were independently found in the replication sample, but the VTA-PBP associations were not. Consistent with theoretical perspectives, the findings suggest that individual differences in pontine reticular formation nuclei contribute to the prominence of autistic features. Specifically, the PCRtA, a nucleus involved in mastication, digestion, and cardio-respiration in animal models, was associated with social communication in children, while the LPB, a pain-network nucleus, was associated with repetitive behaviors. These findings highlight the contributions of key autonomic brainstem nuclei to the expression of core autism features.

Trans-radial artery microcatheter angiography-assisted juvenile ruptured brainstem arteriovenous malformation resection

BACKGROUND

Due to their crucial functional location, surgical treatment of brainstem arteriovenous malformations (AVMs) has always been challenging. For unruptured AVMs, we can determine whether radiological therapy, interventional treatment, or surgical resection is feasible based on the AVM structure. However, for ruptured AVMs, microsurgical resection and interventional embolization are effective methods to prevent further rupture. In the microsurgical resection of AVMs, we usually use a hybrid operation to confirm the AVM structure and determine if the AVM is completely resected during the surgery.

METHOD

We report a case of juvenile ruptured brainstem AVM resection. The right lateral position and left suboccipital retrosigmoid approach were used. We established an interventional approach via left radial artery and set a microcatheter in the feeding artery. Methylene blue injection via a microcatheter showed the AVM structure, and we totally resected the brainstem AVM under electrophysiological monitoring and navigation. Intraoperative angiography was performed to ensure complete resection without residual nidus.

CONCLUSION

This case demonstrates that the trans-radial approach is convenient and safe for special positions in hybrid operations. Methylene blue injection via a microcatheter in the feeding artery provides clearer visualization of the AVM structure under the microscope.

Eagle jugular syndrome accompanied by de novo brainstem cavernous malformation: a case-based systematic review

BACKGROUND

Eagle jugular syndrome (EJS), recently identified as a cause of cerebrovascular disease (CVD) due to venous obstruction by an elongated styloid process (SP), is reported here alongside a case of concurrent de novo cerebral cavernous malformation (CCM). This study aims to explore the potential causal relationship between EJS and de novo CCM through a comprehensive literature review.

METHOD

Systematic literature reviews, spanning from 1995 to 2023, focused on EJS cases with definitive signs and symptoms and de novo CCM cases with detailed clinical characteristics. Data on the pathophysiology and clinical manifestations of EJS, as well as potential risk factors preceding de novo CCM, were collected to assess the relationship between the two conditions.

RESULT

Among 14 patients from 11 articles on EJS, the most common presentation was increased intracranial hypertension (IIH), observed in 10 patients (71.4%), followed by dural sinus thrombosis in four patients (28.6%). In contrast, 30 patients from 28 articles were identified with de novo CCM, involving 37 lesions. In these cases, 13 patients developed CCM subsequent to developmental venous anomalies (43%), seven following dural arteriovenous fistula (dAVF) (23%), and two after sinus thrombosis (6%). In a specific case of de novo brainstem CCM, the development of an enlarged condylar emissary vein, indicative of venous congestion due to IJV compression by the elongated SP, was noted before the emergence of CCM.

CONCLUSION

This study underscores that venous congestion, a primary result of symptomatic EJS, might lead to the development of de novo CCM. Thus, EJS could potentially be an indicator of CCM development. Further epidemiological and pathophysiological investigations focusing on venous circulation are necessary to clarify the causal relationship between EJS and CCM.

Inflammatory lesions of the brainstem: Keys for the diagnosis by MRI

OBJECTIVE

To describe the magnetic resonance imaging (MRI) findings for the most common inflammatory and immune-mediated diseases that involve the brainstem.

CONCLUSION

Inflammatory lesions involving the brainstem are associated with a wide range of autoimmune, infectious, and paraneoplastic syndromes, making the differential diagnosis complex. Being familiar with these entities, their clinical characteristics, and their manifestations on MRI, especially the number of lesions, their shape and extension, and their appearance in different sequences, is useful for orienting the radiological diagnosis.

Volumetric alteration of brainstem in female migraineurs with and without aura

BACKGROUND AND AIM

Brainstem descending modulatory circuits have been postulated to be involved in migraine. Differences in brainstem volume between migraineurs and healthy controls have been demonstrated in previous research, nevertheless, the effect of migraine aura on brainstem volume is still uncertain. The aim of this study was to investigate the brainstem volume in migraineurs and examine the effect of migraine aura on brainstem volume.

METHODS

Our study included 90 female migraine patients without white matter lesions. (29 migraine patients with aura (MwA) and 61 migraine patients without aura (MwoA) and 32 age-matched female healthy controls (HC). Using the FreeSurfer image analysis suite, the volumes of the entire brainstem and its subfields (medulla, pons, and midbrain) were measured and compared between migraine subgroups (MwA vs. MwoA) and the healthy control group. The possible effects of migraine characteristics (i.e., disease duration and migraine attack frequency) on brainstem volume were also investigated.

RESULTS

Migraineurs had greater medulla volume (MwoA 3552 ± 459 mm3, MwA 3424 ± 448 mm3) than healthy controls (3236 ± 411 mm3). Statistically, MwA vs. HC p = 0.040, MwoA vs. HC p = 0.002, MwA vs. MwoA p = 0.555. A significant positive correlation was found between disease duration and the volume of medulla in the whole migraine group (r = 0.334, p = 0.001). Neither the whole brainstem nor its subfields were significantly different in volume between migraine subgroups.

CONCLUSION

Brainstem volume changes in migraine are mainly localized to the medulla and not specific to the presence of aura.

Coexistence of longitudinally extensive transverse myelitis and diffuse midline glioma in the brainstem in an adolescent boy with acute flaccid paralysis

We present the case of a previously healthy 13-year-old boy who was admitted to the emergency department with acute flaccid paralysis. Magnetic resonance imaging revealed radiological evidence of longitudinally extensive transverse myelitis. Additionally, homogeneous T2 signal increase was observed in the pons and medulla oblongata, initially indicating brainstem encephalitis. Subsequent evaluations confirmed a coexistence of diffuse midline glioma (DMG) in the brain stem alongside acute transverse myelitis (ATM). Children with ATM generally have a more favorable prognosis than adults. However, despite the implementation of advanced treatment methods, the patient's quadriplegia did not improve and resulted in spinal cord sequela atrophy. DMG exhibits an aggressive growth pattern and lacks a known curative treatment. This case represents an exceedingly rare synchronous occurrence of aggressive conditions, underscoring the importance of raising awareness among physicians. Furthermore, we aim to discuss the radiologic differential diagnosis, as this is the first documented instance in the literature.

ProbaStem, a pipeline towards the first high-resolution probabilistic atlas of the whole human brainstem

The brainstem plays an essential role in many vital functions, such as autonomic control, consciousness and sleep, motricity, somatic afferent function, and cognition. Its involvement in several neurological diseases and the definition of brainstem targets for deep brain stimulation (DBS) explain the need for brainstem atlases describing its structural organization and connectivity from several modalities, from histology to ultrahigh field ex vivo MRI. Nonetheless, these atlases are often limited to a subpart of the brainstem or only include a single subject, the brainstem variability being considered low. This paper proposes a pipeline to create a high-resolution multisubject probabilistic atlas of the whole human brainstem based on four ultrahigh field ex vivo MRI datasets. The variability of the brainstem structures appears higher than usually considered, both for the volume and position of the central gray matter structures of the brainstem. This justifies the creation of atlases that capture the anatomical variability across subjects. The one we present here only included four specimens, but can easily be incremented due to its highly flexible design.

The Interaural Time Difference for High-Pass Filtered Noise and Its Relationship With Brainstem Dysfunction and Disability in Multiple Sclerosis

PURPOSE

Just noticeable difference for interaural time difference (JND-ITD) is a sensitive test to detect silent lesions and neural asynchrony along the auditory pathways among individuals with multiple sclerosis (MS), but it has not been studied with brainstem functional system scores (BFSS) and expanded disability status scale (EDSS). The study aims to assess the usefulness of JND-ITD thresholds in individuals with MS and relate to brainstem magnetic resonance imaging (MRI) lesions, BFSS, and disability (EDSS).

METHOD

Standard group comparison design was adapted to compare the JND-ITD thresholds between individuals with MS (n = 45) and age and gender-matched healthy participants (n = 45). All participants underwent case history, neurological examination including BFSS and EDSS scoring, MRI brain imaging, minimental state examination, routine audiological evaluation, and ITD testing for high-pass filtered noise stimuli.

RESULTS

Of the 36 MS participants with abnormal JND-ITD thresholds, 22 (48.9%) participants could not identify maximum JND-ITD values (1,280 μs) in the ITD task. Abnormal JND-ITDs thresholds (139-1,280 μs) were obtained in 14 (31.11%) participants with MS. The JND-ITD thresholds were significantly different between the healthy and MS group. No significant association was found between the presence of ITD abnormality with the presence of brainstem lesions (MRI) and brainstem dysfunction (BFSS). Also, this study did not find any relationship between JND-ITD thresholds with disability (EDSS).

CONCLUSIONS

This study supports the findings that JND-ITD for high-pass filtered noise is a sensitive test to detect lesions along the auditory system. Even though JND-ITD thresholds did not relate with BFSS and EDSS scores, JND-ITD abnormalities can be of great value in identifying lesions along the auditory system, especially in the early stages of MS, when clinical neurological examination does not show any signs of brainstem dysfunction, disability, and MRI without any lesions in the brain.

Delayed onset Bickerstaff brainstem encephalitis overlapping Miller-Fisher Syndrome during SARS-CoV-2 infection

Bickerstaff brainstem encephalitis (BBE) is a neuroimmunologic disease characterized by the acute onset of external ophthalmoplegia, ataxia, and consciousness disturbance, mostly subsequent to an infection. BBE is considered to be a variant of Miller-Fisher syndrome (MFS), which also exhibits external ophthalmoplegia and ataxia but not presenting consciousness alterations. Therefore, these two medical conditions are included in the clinical spectrum of the "Fisher-Bickerstaff syndrome" ( Shahrizaila and Yuki in J Neurol Neurosurg Psychiatry 84(5):576-583) [1]. With regard to the etiopathogenesis, increasing evidence worldwide suggests that SARS-CoV-2 infection-enhanced immune response is involved in a wide range of neurological complications such as Guillain-Barré syndrome (GBS), MFS, acute necrotizing encephalitis (ANE), myelitis, acute disseminated encephalomyelitis (ADEM), and, although very rarely, BBE either (Hosseini et al. in Rev Neurosci 32:671-691) [2]. We report a case of a patient affected by delayed onset BBE overlapping MFS during a mild SARS-CoV-2 infection. To the best of our knowledge, similar cases have never been reported.

The Effect of Posterior Fossa Decompression Surgery on Brainstem and Cervical Spinal Cord Dimensions in Adults with Chiari Malformation Type 1

OBJECTIVE

Posterior fossa decompression (PFD) surgery creates more space at the skull base, reduces the resistance to the cerebrospinal fluid motion, and alters craniocervical biomechanics. In this paper, we retrospectively examined the changes in neural tissue dimensions following PFD surgery on Chiari malformation type 1 adults.

METHODS

Measurements were performed on T2-weighted brain magnetic resonance images acquired before and 4 months after surgery. Measurements were conducted for neural tissue volume and spinal cord/brainstem width at 4 different locations; 2 width measurements were made on the brainstem and 2 on the spinal cord in the midsagittal plane. Cerebellar tonsillar position (CTP) was also measured before and after surgery.

RESULTS

Twenty-five adult patients, with a mean age of 38.9 ± 8.8 years, were included in the study. The cervical cord volume increased by an average of 2.3 ± 3.3% (P = 0.002). The width at the pontomedullary junction increased by 2.2 ± 3.5% (P < 0.01), while the width 10 mm caudal to this junction increased by 4.2 ± 3.9% (P < 0.0001). The spinal cord width at the base of second cervical vertebra and third cervical vertebra did not significantly change after surgery. The CTP decreased by 60 ± 37% (P < 0.0001) after surgery, but no correlation was found between CTP change and dimension change.

CONCLUSIONS

The brainstem width and cervical cord volume showed a modest increase after PFD surgery, although standard deviations were large. A reduction in compression after PFD surgery may allow for an increase in neural tissue dimension. However, clinical relevance is unclear and should be assessed in future studies with high-resolution imaging.

Intraoperative Neurophysiologic Monitoring in Predicting Dysphagia After Brainstem and Fourth Ventricle Surgery

OBJECTIVE

Dysphagia represents the main complication of posterior fossa neurosurgery. Adequate diagnosis of this complication is warranted to prevent untimely extubation with subsequent aspiration. Intraoperative neurophysiologic monitoring (IONM) modalities may be used for this purpose. However, it is not known which IONM modality may be significant for diagnosis. This study aimed to define the most significant IONM modality for dysphagia prognostication after posterior fossa neurosurgery.

METHODS

The analysis included 46 patients (34 with tumors of the fourth ventricle and 12 with brainstem localization) who underwent surgical excision of the tumor. Neurologic symptoms before and after neurosurgery were noted and magnetic resonance imaging with the subsequent volume estimation of the removed mass was performed, followed by an IONM findings analysis (mapping of the nucleus of the caudal cranial nerves [CN] and corticobulbar motor-evoked potentials [CoMEP]).

RESULTS

Aggravation of dysphagia was noted in 24% of the patients, more often in patients with tumor localization in the fourth ventricle (26%) than in those with brainstem mass lesions (16%). Mapping of the caudal cranial nerve nuclei did not correlate with the dysfunction of these structures. CoMEP was significantly associated with the neurologic state of the CN. The decrease in CoMEP is a significant prognostic factor for postoperative bulbar symptoms appearance or aggravation.

CONCLUSIONS

Mapping the CN is an important identification tool. The CoMEP modality should be used intraoperatively to determine the functional state of the CN and predict postoperative dysphagia.

Intrinsic epidermoid cyst of the brainstem in children-review and case report

PURPOSE

The study aimed to summarize all published cases of intrinsic brainstem epidermoid cysts in a timeline to highlight the specific characteristics and individualize the disease, in addition to discussing the best treatment used.

METHODS

The scientific literature on pediatric cases of intrinsic epidermoid cysts of the brainstem was analyzed. We present the case of a 1.5-year-old male with incidental presentation, who was treated with gross total resection. We summarize all previously published cases to individualize the disease.

RESULTS

We identified 21 patients, including 10 boys and 11 girls, with a mean age of 4.85 (1-15) years at the time of surgery. The most frequent symptoms were cranial nerve palsy (71.4%), pyramidal tract deficit (57.14%), and headache (52.38%). Among the affected cranial nerves, VII was the most frequently reported in 10 patients.

CONCLUSION

Brainstem epidermoid cysts are extremely rare pathologies with relevant age involvement in young children. The treatment objective should be the maximum resection of the lesion through a careful approach and with the appropriate tools for the functional preservation of the patient.

The Effect of the Human Brainstem Myelination on Gait Speed in Normative Aging

The brainstem functions as a relay and integrative brain center and plays an essential role in motor function. Whether brainstem tissue deterioration, including demyelination, affects motor function has not been studied. Understanding the potential relationship between brainstem demyelination and motor function may be useful for the early diagnosis of neurodegenerative diseases and to understand age-related gait impairments that have no apparent cause. In this work, we investigated the associations between rapid or usual gait speeds, as integrative measures of motor function, and cerebral myelin content. In 118 individuals (age 22-94 years) free of neurodegenerative diseases or cognitive impairment, myelin content was assessed as the myelin water fraction, a direct magnetic resonance imaging measure of myelin content, and longitudinal and transverse relaxation rates (R1 and R2), which are sensitive magnetic resonance imaging measures of myelin content. Our results indicate that participants with lower usual or rapid gait speed exhibited lower values of myelin water fraction and R1 in the main brainstem regions, which were more evident and statistically significant in the midbrain. In contrast, we found no significant associations between gait speeds and R2, an expected result because various physiological factors confound R2. These original findings provide evidence that the level of brainstem myelination may affect gait performance among cognitively unimpaired adults who are free from any clinically detectable neurodegenerative diseases. Further studies are needed to understand the longitudinal changes in brainstem myelination with aging and neurodegenerative diseases, including Alzheimer's disease and Parkinson's disease.

In vivo marker of brainstem myelin is associated to quantitative sleep parameters in healthy young men

The regional integrity of brain subcortical structures has been implicated in sleep-wake regulation, however, their associations with sleep parameters remain largely unexplored. Here, we assessed association between quantitative Magnetic Resonance Imaging (qMRI)-derived marker of the myelin content of the brainstem and the variability in the sleep electrophysiology in a large sample of 18-to-31 years healthy young men (N = 321; ~ 22 years). Separate Generalized Additive Model for Location, Scale and Shape (GAMLSS) revealed that sleep onset latency and slow wave energy were significantly associated with MTsat estimates in the brainstem (pcorrected ≤ 0.03), with overall higher MTsat value associated with values reflecting better sleep quality. The association changed with age, however (MTsat-by-age interaction-pcorrected ≤ 0.03), with higher MTsat value linked to better values in the two sleep metrics in the younger individuals of our sample aged ~ 18 to 20 years. Similar associations were detected across different parts of the brainstem (pcorrected ≤ 0.03), suggesting that the overall maturation and integrity of the brainstem was associated with both sleep metrics. Our results suggest that myelination of the brainstem nuclei essential to regulation of sleep is associated with inter-individual differences in sleep characteristics during early adulthood. They may have implications for sleep disorders or neurological diseases related to myelin.

Brainstem anatomy with 7-T MRI: in vivo assessment and ex vivo comparison

BACKGROUND

The brainstem contains grey matter nuclei and white matter tracts to be identified in clinical practice. The small size and the low contrast among them make their in vivo visualisation challenging using conventional magnetic resonance imaging (MRI) sequences at high magnetic field strengths. Combining higher spatial resolution, signal- and contrast-to-noise ratio and sensitivity to magnetic susceptibility (χ), susceptibility-weighted 7-T imaging could improve the assessment of brainstem anatomy.

METHODS

We acquired high-resolution 7-T MRI of the brainstem in a 46-year-old female healthy volunteer (using a three-dimensional multi-echo gradient-recalled-echo sequence; spatial resolution 0.3 × 0.3 × 1.2 mm3) and in a brainstem sample from a 48-year-old female body donor that was sectioned and stained. Images were visually assessed; nuclei and tracts were labelled and named according to the official nomenclature.

RESULTS

This in vivo imaging revealed structures usually evaluated through light microscopy, such as the accessory olivary nuclei, oculomotor nucleus and the medial longitudinal fasciculus. Some fibre tracts, such as the medial lemniscus, were visible for most of their course. Overall, in in vivo acquisitions, χ and frequency maps performed better than T2*-weighted imaging and allowed for the evaluation of a greater number of anatomical structures. All the structures identified in vivo were confirmed by the ex vivo imaging and histology.

CONCLUSIONS

The use of multi-echo GRE sequences at 7 T allowed the visualisation of brainstem structures that are not visible in detail at conventional magnetic field and opens new perspectives in the diagnostic and therapeutical approach to brain disorders.

RELEVANCE STATEMENT

In vivo MR imaging at UHF provides detailed anatomy of CNS substructures comparable to that obtained with histology. Anatomical details are fundamentals for diagnostic purposes but also to plan a direct targeting for a minimally invasive brain stimulation or ablation.

KEY POINTS

• The in vivo brainstem anatomy was explored with ultrahigh field MRI (7 T). • In vivo T2*-weighted magnitude, χ, and frequency images revealed many brainstem structures. • Ex vivo imaging and histology confirmed all the structures identified in vivo. • χ and frequency imaging revealed more brainstem structures than magnitude imaging.

Dysphagia at 1 Year is Associated With Mean Dose to the Inferior Section of the Brain Stem

PURPOSE

Dysphagia is a common toxicity after head and neck (HN) radiation therapy that negatively affects quality of life. We explored the relationship between radiation therapy dose to normal HN structures and dysphagia 1 year after treatment using image-based datamining (IBDM), a voxel-based analysis technique.

METHODS AND MATERIALS

We used data from 104 patients with oropharyngeal cancer treated with definitive (chemo)radiation therapy. Swallow function was assessed pretreatment and 1 year posttreatment using 3 validated measures: MD Anderson Dysphagia Inventory (MDADI), performance status scale for normalcy of diet (PSS-HN), and water swallowing test (WST). For IBDM, we spatially normalized all patients' planning dose matrices to 3 reference anatomies. Regions where the dose was associated with dysphagia measures at 1 year were found by performing voxel-wise statistics and permutation testing. Clinical factors, treatment variables, and pretreatment measures were used in multivariable analysis to predict each dysphagia measure at 1 year. Clinical baseline models were found using backward stepwise selection. Improvement in model discrimination after adding the mean dose to the identified region was quantified using the Akaike information criterion. We also compared the prediction performance of the identified region with a well-established association: mean doses to the pharyngeal constrictor muscles.

RESULTS

IBDM revealed highly significant associations between dose to distinct regions and the 3 outcomes. These regions overlapped around the inferior section of the brain stem. All clinical models were significantly improved by including mean dose to the overlap region (P ≤ .006). Including pharyngeal dosimetry significantly improved WST (P = .04) but not PSS-HN or MDADI (P ≥ .06).

CONCLUSIONS

In this hypothesis-generating study, we found that mean dose to the inferior section of the brain stem is strongly associated with dysphagia 1 year posttreatment. The identified region includes the swallowing centers in the medulla oblongata, providing a possible mechanistic explanation. Further work including validation in an independent cohort is required.

Reduced brainstem volume is associated with mobility impairments in youth with cerebral palsy

BACKGROUND

Persons with cerebral palsy (CP) have impaired mobility that has been attributed to changes in structure and function within the nervous system. The brainstem is a region that plays a critical role in mobility by connecting the cortex and cerebellum to the spinal cord, yet this region has been largely unstudied in persons with CP.

RESEARCH QUESTION

We used high-resolution structural MRI and biomechanical analyses to examine whether the volume of the whole brainstem and its constituent elements are altered in CP and if these alterations relate to the mobility impairments within this population.

METHODS

A cohort study was conducted to assess the volume of the whole brainstem, pons, midbrain, medulla, and superior cerebellar peduncle in a cohort of persons with CP (N = 26; Age = 16.3 ± 1.0 years; GMFCS levels I-IV, Females = 12) and a cohort of neurotypical (NT) controls (N = 38; Age = 14.3 ± 0.4 years, Females = 14) using structural MR imaging of the brainstem. Outside the scanner, a digital mat was used to quantify the spatiotemporal gait biomechanics of these individuals.

RESULTS

We found a significant decrease in volume of the total brainstem, midbrain, and pons in persons with CP in comparison to the NT controls. Furthermore, we found that the altered volumes were related to reduced gait velocity and step length.

SIGNIFICANCE

The structural changes in the brainstems of persons with CP may contribute to the mobility impairments that are ubiquitous within this population.

Assessment of brainstem function and haemodynamics by MRI: challenges and clinical prospects

MRI offers techniques for non-invasively measuring a range of aspects of brain tissue function. Blood oxygenation level dependent (BOLD) functional magnetic resonance imaging (fMRI) is widely used to assess neural activity, based on the brain's haemodynamic response, while arterial spin labelling (ASL) MRI is a non-invasive method of quantitatively mapping cerebral perfusion. Both techniques can be applied to measure cerebrovascular reactivity (CVR), an important marker of the health of the cerebrovascular system. BOLD, ASL and CVR have been applied to study a variety of disease processes and are already used in certain clinical circumstances. The brainstem is a critical component of the central nervous system and is implicated in a variety of disease processes. However, its function is difficult to study using MRI because of its small size and susceptibility to physiological noise. In this article, we review the physical and biological underpinnings of BOLD and ASL and their application to measure CVR, discuss the challenges associated with applying them to the brainstem and the opportunities for brainstem MRI in the research and clinical settings. With further optimisation, functional MRI techniques could feasibly be used to assess brainstem haemodynamics and neural activity in the clinical setting.

Amide proton transfer-weighted imaging of pediatric brainstem glioma and its predicted value for H3 K27 alteration

BACKGROUND

Non-invasive determination of H3 K27 alteration of pediatric brainstem glioma (pedBSG) remains a clinical challenge.

PURPOSE

To predict H3 K27-altered pedBSG using amide proton transfer-weighted (APTw) imaging.

MATERIAL AND METHODS

This retrospective study included patients with pedBSG who underwent APTw imaging and had the H3 K27 alteration status determined by immunohistochemical staining. The presence or absence of foci of markedly increased APTw signal in the lesion was visually assessed. Quantitative APTw histogram parameters within the entire solid portion of tumors were extracted and compared between H3 K27-altered and wild-type groups using Student's t-test. The ability of APTw for differential diagnosis was evaluated using logistic regression.

RESULTS

Sixty pedBSG patients included 48 patients with H3 K27-altered tumor (aged 2-48 years) and 12 patients with wild-type tumor (aged 3-53 years). Visual assessment showed that the foci of markedly increased APTw signal intensity were more common in the H3 K27-altered group than in wild-type group (60% vs. 16%, P = 0.007). Histogram parameters of APTw signal intensity in the H3 K27-altered group were significantly higher than those in the wild-type group (median, 2.74% vs. 2.22%, P = 0.02). The maximum (area under the receiver operating characteristic curve [AUC] = 0.72, P = 0.01) showed the highest diagnostic performance among histogram analysis. A combination of age, median and maximum APTw signal intensity could predict H3 K27 alteration with a sensitivity of 81%, specificity of 75% and AUC of 0.80.

CONCLUSION

APTw imaging may serve as an imaging biomarker for H3 K27 alteration of pedBSGs.

Causal influence of brainstem response to transcutaneous vagus nerve stimulation on cardiovagal outflow

BACKGROUND

The autonomic response to transcutaneous auricular vagus nerve stimulation (taVNS) has been linked to the engagement of brainstem circuitry modulating autonomic outflow. However, the physiological mechanisms supporting such efferent vagal responses are not well understood, particularly in humans.

HYPOTHESIS

We present a paradigm for estimating directional brain-heart interactions in response to taVNS. We propose that our approach is able to identify causal links between the activity of brainstem nuclei involved in autonomic control and cardiovagal outflow.

METHODS

We adopt an approach based on a recent reformulation of Granger causality that includes permutation-based, nonparametric statistics. The method is applied to ultrahigh field (7T) functional magnetic resonance imaging (fMRI) data collected on healthy subjects during taVNS.

RESULTS

Our framework identified taVNS-evoked functional brainstem responses with superior sensitivity compared to prior conventional approaches, confirming causal links between taVNS stimulation and fMRI response in the nucleus tractus solitarii (NTS). Furthermore, our causal approach elucidated potential mechanisms by which information is relayed between brainstem nuclei and cardiovagal, i.e., high-frequency heart rate variability, in response to taVNS. Our findings revealed that key brainstem nuclei, known from animal models to be involved in cardiovascular control, exert a causal influence on taVNS-induced cardiovagal outflow in humans.

CONCLUSION

Our causal approach allowed us to noninvasively evaluate directional interactions between fMRI BOLD signals from brainstem nuclei and cardiovagal outflow.

Bickerstaff's brainstem encephalitis: a rare case of neurologic complication in Ulcerative Colitis

Bickerstaff's brainstem encephalitis is a rare autoimmune disorder that presents with ataxia, ophthalmoplegia, disturbance of consciousness and quadriplegia. A 45-year-old man with a history of ulcerative colitis (UC) taking mesalazine (5-aminosalicylic acid) visited the emergency room presenting with ataxia, ophthalmoplegia and a progressively worsening cognitive impairment. Cerebrospinal fluid analysis showed mild elevation in protein and white blood cell count and increased intracranial pressure. Anti-GQ1b autoantibodies were found positive in the patient's serum and contrast-enhanced brain magnetic resonance imaging showed diffuse leptomeningeal enhancement and pontine lesions. Based on these findings and the patient's clinical course and history, he was diagnosed with Bickerstaff's brainstem encephalitis. Mesalazine was discontinued and high-dose steroid pulse therapy was started, followed by intravenous immunoglobulin, which resulted in gradual improvement of the neurologic symptoms. When an ulcerative colitis patient presents with progressive cognitive impairment, quadriplegia and disturbance of consciousness and gait, Bickerstaff brainstem encephalitis should be considered in the differential diagnosis and prompt immunotherapy may lead to favorable prognosis.

Dandy-Walker Phenotype with Brainstem Involvement: 2 Distinct Subgroups with Different Prognosis

BACKGROUND AND PURPOSE

Although cardinal imaging features for the diagnostic criteria of the Dandy-Walker phenotype have been recently defined, there is a large range of unreported malformations among these patients. The brainstem, in particular, deserves careful attention because malformations in this region have potentially important implications for clinical outcomes. In this article, we offer detailed information on the association of brainstem dysgenesis in a large, multicentric cohort of patients with the Dandy-Walker phenotype, defining different subtypes of involvement and their potential clinical impact.

MATERIALS AND METHODS

In this established multicenter cohort of 329 patients with the Dandy-Walker phenotype, we include and retrospectively review the MR imaging studies and clinical records of 73 subjects with additional brainstem malformations. Detailed evaluation of the different patterns of brainstem involvement and their potential clinical implications, along with comparisons between posterior fossa measurements for the diagnosis of the Dandy-Walker phenotype, was performed among the different subgroups of patients with brainstem involvement.

RESULTS

There were 2 major forms of brainstem involvement in patients with Dandy-Walker phenotype including the following: 1) the mild form with anteroposterior disproportions of the brainstem structures "only" (57/73; 78%), most frequently with pontine hypoplasia (44/57; 77%), and 2) the severe form with patients with tegmental dysplasia with folding, bumps, and/or clefts (16/73; 22%). Patients with severe forms of brainstem malformation had significantly increased rates of massive ventriculomegaly, additional malformations involving the corpus callosum and gray matter, and interhemispheric cysts. Clinically, patients with the severe form had significantly increased rates of bulbar dysfunction, seizures, and mortality.

CONCLUSIONS

Additional brainstem malformations in patients with the Dandy-Walker phenotype can be divided into 2 major subgroups: mild and severe. The severe form, though less prevalent, has characteristic imaging features, including tegmental folding, bumps, and clefts, and is directly associated with a more severe clinical presentation and increased mortality.

Adult-onset Alexander disease with brainstem and cervical cord enhancing lesions

Leukodystrophies are a group of genetic diseases with diverse clinical features and prominent involvement of the central nervous system white matter. We describe a 27-year-old man who presented with a progressive neurological disease, and striking involvement of the brainstem and symmetrical white matter lesions on MR scanning. Having excluded several other causes of leukodystrophy, we confirmed Alexander disease when a genetic panel showed a probable pathogenic variant in GFAP: p.Leu359Pro. Clinicians should suspect Alexander disease in people with a progressive neurological motor decline who has pyramidal and bulbar signs and compatible neuroimaging.

Alterations of brainstem volume in patients with first-episode and recurrent major depressive disorder

BACKGROUND

Major depressive disorder (MDD) is a prevalent mental health condition characterized by recurrent episodes in a substantial proportion of patients. The number of previous episodes is one of the most crucial predictors of depression recurrence. However, the underlying neural mechanisms remain unclear. To date, there have been limited neuroimaging studies investigating morphological changes of the brainstem in patients with first-episode MDD (FMDD) and recurrent MDD (RMDD). This study aimed to examine volumetric changes of individual brainstem regions in relation to the number of previous episodes and disease duration.

METHOD

A total of 111 individuals including 36 FMDD, 25 RMDD, and 50 healthy controls (HCs) underwent T1-weighted structural magnetic resonance imaging scans. A Bayesian segmentation algorithm was used to analyze the volume of each brainstem region, including the medulla oblongata, pons, midbrain, and superior cerebellar peduncle (SCP), as well as the whole brainstem volume. Analyses of variance (ANOVA) were performed to obtain brain regions with significant differences among three groups and then post hoc tests were calculated for inter-group comparisons. Partial correlation analyses were further conducted to identify associations between regional volumes and clinical features.

RESULTS

The ANOVA revealed significant brainstem volumetric differences among three groups in the pons, midbrain, SCP, and the whole brainstem (F = 3.996 ~ 5.886, adjusted p = 0.015 ~ 0.028). As compared with HCs, both groups of MDD patients showed decreased volumes in the pons as well as the entire brainstem (p = 0.002 ~ 0.034), however, only the FMDD group demonstrated a significantly reduced volume in the midbrain (p = 0.003). Specifically, the RMDD group exhibited significantly decreased SCP volume when comparing to both FMDD (p = 0.021) group and HCs (p = 0.008). Correlation analyses revealed that the SCP volumes were negatively associated with the number of depressive episodes (r=-0.36, p < 0.01) and illness duration (r=-0.28, p = 0.035) in patients with MDD.

CONCLUSION

The present findings provided evidence of decreased brainstem volume involving in the pathophysiology of MDD, particularly, volumetric reduction in the SCP might represent a neurobiological marker for RMDD. Further research is needed to confirm our observations and deepen our understanding of the neural mechanisms underlying depression recurrence.

How to predict the outcome of primary brainstem hemorrhage: Six-year results of a single-center retrospective analysis

Primary brainstem hemorrhage (PBH) is one of the most fatal intracranial hemorrhages, evaluating the prognosis in the early stage is vital for appropriate therapeutic planning. Our study aimed to identify risk factors for 30-day mortality and 90-day functional recovery of PBH. Data from 63 patients with PBH admitted to Beijing Chaoyang Hospital between 2016 and 2022 were retrieved for this study. We grouped the patients according to 30-day survival or 90-day functional recovery. Independent risk factors of 30-day mortality and 90-day functional recovery were identified by univariate and multivariate logistic regression analyses. 31 patients (49.2%) died within 30 days and 22 patients (34.9%) achieved better functional recovery. By multivariate analysis, Glasgow coma scale <9 on admission and tachycardia were significantly associated with 30-day mortality, while the hematoma volume >5 mL was an independent risk factor for 90-day functional recovery. Initial level of consciousness, tachycardia, massive hematoma were risk factors for prognosis, which must be seriously evaluated for therapeutic planning.

Clinical features of MOGAD with brainstem involvement in the initial attack versus NMOSD and MS

OBJECTIVE

To assess the characteristics of Myelin oligodendrocyte glycoprotein (MOG) antibody-associated disorder (MOGAD) with brainstem involvement in the first event (BSIFE) and make comparisons with aquaporin-4-IgG seropositive neuromyelitis optica spectrum disorder (AQP4-IgG-NMOSD) and multiple sclerosis (MS).

METHODS

From 2017 to 2022, this study identified MOG-IgG-positive patients with brainstem or both brainstem and cerebellum lesions in the first episode. As a comparison group, AQP4-IgG-NMOSD (n = 30) and MS (n = 30) patients with BSIFE were enroled.

RESULTS

Thirty-five patients (35/146, 24.0%) were the BSIFE of MOGAD. Isolated brainstem episodes occurred in 9 of the 35 (25.7%) MOGAD patients, which was similar to MS (7/30, 23.3%) but was lower than AQP4-IgG-NMOSD (17/30, 56.7%, P = 0.011). Pons (21/35, 60.0%), medulla oblongata (20/35, 57.1%) and middle cerebellar peduncle (MCP, 19/35, 54.3%) were the most frequently affected areas. Intractable nausea (n = 7), vomiting (n = 8) and hiccups (n = 2) happened in MOGAD patients, but EDSS of MOGAD was lower than AQP4-IgG-NMOSD (P = 0.001) at the last follow-up. MOGAD patients with or without BSIFE did not significantly differ in terms of the ARR (P = 0.102), mRS (P = 0.823), or EDSS (P = 0.598) at the most recent follow-up. Specific oligoclonal bands appeared in MOGAD (13/33, 39.4%) and AQP4-IgG-NMOSD (7/24, 29.2%) in addition to MS (20/30, 66.7%). Fourteen MOGAD patients (40.0%) experienced relapse in this study. When the brainstem was involved in the first attack, there was an increased likelihood of a second attack occurring at the same location (OR=12.22, 95%CI 2.79 to 53.59, P = 0.001). If the first and second events were both in the brainstem, the third event was likely to occur at the same location (OR=66.00, 95%CI 3.47 to 1254.57, P = 0.005). Four patients experienced relapses after the MOG-IgG turned negative.

CONCLUSION

BSIFE occurred in 24.0% of MOGAD. Pons, medulla oblongata and MCP were the most frequently involved regions. Intractable nausea, vomiting and hiccups occurred in MOGAD and AQP4-IgG-NMOSD, but not MS. The prognosis of MOGAD was better than AQP4-IgG-NMOSD. In contrast to MS, BSIFE may not indicate a worse prognosis for MOGAD. When patients with BSIFE, MOGAD tent to reoccur in the brainstem. Four of the 14 recurring MOGAD patients relapsed after the MOG-IgG test turned negative.

Altered resting-state effective connectivity of trigeminal vascular system in migraine without aura: A spectral dynamic causal modeling study

BACKGROUND

The trigeminal vascular system is an important part of the anatomical and physiological basis of migraine. The effective connectivity (EC) among the regions of interest (ROIs) in the trigeminal vascular system involved in migraine without aura (MWoA) remains unclear.

METHODS

In this cross-sectional study, 48 patients (mean [SD] age 38.06 [10.35] years; male, 14/48 [29%]) with MWoA during the interictal phase and 48 healthy controls of similar age and sex (mean [SD] age 38.96 [10.96] years; male, 14/48 [29%]) underwent resting-state functional magnetic resonance imaging (fMRI). Dynamic causal modeling analysis was conducted to investigate directional EC among ROIs in the trigeminal vascular system including the bilateral brainstem, the primary somatosensory cortex (S1), the thalamus, and the insula.

RESULTS

Compared with the healthy control group, MWoA represented significantly reduced EC from the left brainstem (Brainstem.L) to the left insula (MWoA: mean [SD] -0.16 [0.36]; healthy controls: mean [SD] 0.11 [0.41]; Pcorrected  = 0.021), reduced EC from the Brainstem.L to the right insula (MWoA: mean [SD] -0.15 [0.39]; healthy controls: mean [SD] 0.03 [0.35]; Pcorrected  = 0.021), and decreased EC from the left thalamus (Thalamus.L) to the Brainstem.L (MWoA: mean [SD] -0.13 [0.56]; healthy controls: mean [SD] 0.10 [0.45]; Pcorrected  = 0.021). Altered EC parameters were not significantly correlated with MWoA clinical data.

CONCLUSION

These results further provide increasing evidence that disturbed homeostasis of the trigeminovascular nociceptive pathway is involved in the pathophysiological mechanisms of migraine. Patients with MWoA exhibited a regional interaction distinct from healthy controls in the neural pathway of the Bilateral Insula-Brainstem.L-Thalamus.L, which may shed light on the future understanding of brain mechanisms for MWoA. Future brain-based interventions are suggested to consider the dysregulation in the Bilateral Insula-Brainstem.L-Thalamus.L circuits.

Dilated Virchow Robin spaces in brainstem

Virchow Robin spaces are normally found pial-lined perivascular spaces traversing from subarachnoid space to the brain parenchyma. Giant dilated Virchow robin spaces (dVRS) are rare. They do not require any surgical intervention unless they are causing symptoms. Here we report a young boy with an incidentally detected giant dVRS in brainstem which was referred for surgery with an initial impression of glioma. Knowledge about such an entity is important to prevent mismanagement.

Infratentorial brain injury and death by neurologic criteria in Canada: a narrative review

There are two anatomic formulations of death by neurologic criteria accepted worldwide: whole-brain death and brainstem death. As part of the Canadian Death Definition and Determination Project, we convened an expert working group and performed a narrative review of the literature. Infratentorial brain injury (IBI) with an unconfounded clinical assessment consistent with death by neurologic criteria represents a nonrecoverable injury. The clinical determination of death cannot distinguish between IBI and whole-brain cessation of function. Current clinical, functional, and neuroimaging assessments cannot reliably confirm the complete and permanent destruction of the brainstem. No patient with isolated brainstem death has been reported to recover consciousness and all patients have died. Studies suggest a significant majority of isolated brainstem death will evolve into whole-brain death, influenced by time/duration of somatic support and impacted by ventricular drainage and/or posterior fossa decompressive craniectomy. Acknowledging variability in intensive care unit (ICU) physician opinion on this matter, a majority of Canadian ICU physicians would perform ancillary testing for death determination by neurologic criteria in the context of IBI. There is currently no reliable ancillary test to confirm complete destruction of the brainstem; ancillary testing currently includes evaluation of both infratentorial and supratentorial flow. Acknowledging international variability in this regard, the existing evidence reviewed does not provide sufficient confidence that the clinical exam in IBI represents a complete and permanent destruction of the reticular activating system and thus the capacity for consciousness. On this basis, IBI consistent with clinical signs of death by neurologic criteria without significant supratentorial involvement does not fulfill criteria for death in Canada and ancillary testing is required.