The Innervation of the Cranial Dura Mater: Neurosurgical Case Correlates and a Review of the Literature

Characterizing neuroinvasion and neuropathology of SARS-CoV-2 by using AC70 human ACE2 transgenic mice

COVID-19 presents with a plethora of neurological signs and symptoms despite being characterized as a respiratory disease, including seizures, anxiety, depression, amnesia, attention deficits, and alterations in consciousness. The olfactory nerve is widely accepted as the neuroinvasive route by which the etiological agent SARS-CoV-2 enters the brain, but the trigeminal nerve is an often-overlooked additional route. Based on this consensus, we initially conducted a pilot experiment investigating the olfactory nerve route of SARS-CoV-2 neuroinvasion via intranasal inoculation in AC70 human ACE2 transgenic mice. Notably, we found that the trigeminal ganglion is an early and highly efficient site of viral replication, which then rapidly spread widely throughout the brain where neurons were primarily targeted. Despite the extensive viral infection across the brain, obvious evidence of tissue pathology including inflammatory infiltration, glial activation, and apoptotic cell deaths were not consistently observed, albeit inflammatory cytokines were significantly induced. However, the expression levels of different genes related to neuronal function, including the neurotransmitter dopamine pathway as well as synaptic function, and markers of neuronal damage were altered as compared to mock-infected mice. Our findings suggest that the trigeminal nerve may serve as a neuroinvasive route complementary to the olfactory nerve and that the ensuing neuroinvasion presented a unique neuropathological profile. This study provides insights into potential neuropathogenic mechanisms utilized by coronaviruses.

Novel aspects of signal processing in lamina I

The most superficial layer of the spinal dorsal horn, lamina I, is a key element of the nociceptive processing system. It contains different types of projection neurons (PNs) and local-circuit neurons (LCNs) whose functional roles in the signal processing are poorly understood. This article reviews recent progress in elucidating novel anatomical features and physiological properties of lamina I PNs and LCNs revealed by whole-cell recordings in ex vivo spinal cord. This article is part of the Special Issue on "Ukrainian Neuroscience".

Risk Factors for Headache Disorder in Patients With Unruptured Intracranial Aneurysms

OBJECTIVE

Headache disorders are a prevalent yet frequently underestimated issue in patients with unruptured intracranial aneurysms (UIAs). The primary aim of this study is to systematically examine the incidence, specific characteristics, and associated risk factors of headache disorders in the context of individuals diagnosed with UIAs. Through this investigation, we hope to contribute valuable insights to the current understanding of this complex relationship and potentially inform future diagnostic and treatment approaches.

METHODS

Data from 146 consecutive patients harboring UIAs were evaluated. The location and morphological characteristics of the aneurysm were analyzed. Factors associated with headache incidence and methods of treatment were investigated. The headache pattern in 48 patients was assessed using self-reported questionnaires.

RESULTS

A total of 146 patients were identified. Out of 146 patients, 95 (65%) were in the Headache Group (HG) and 51 (35%) were asymptomatic and in the No Headache Group (NHG). Factors associated with a higher likelihood of headache were past or current tobacco, alcohol, and illicit drug use (p=0.029). On average, patients had 1.49 (SD=1) aneurysms in the HG and 1.43 (SD=.92) in the NHG group, respectively. In our series, the size of aneurysms, the status of the aneurysm (treated vs untreated), and the method of treatment did not significantly differ between the groups. There was a high incidence of headaches in patients with aneurysms of the ophthalmic segment (C6) of the internal carotid artery (ICA) and sphenoidal segment (M1) of the middle cerebral artery (MCA). Of 48 patients that completed headache questionnaires, 25 had headaches on more than 15 days a month. The majority of participants (85.4%) reported the severity of their pain as being greater than 5 on a scale of 10, while one-third (33.3%) experienced the maximum pain level of 10 out of 10.

CONCLUSION

Headache more often occurs in patients with aneurysms of the ophthalmic segment (C6) of the ICA and sphenoidal segment (M1) of the MCA. Its distinctive features are deep pain for more than 15 days a month. Although the treatment of aneurysms reduces the risk of aneurysmal rupture, its efficacy in relieving the headache is still uncertain.

Orofacial Migraine or Neurovascular Orofacial Pain from Pathogenesis to Treatment

The purpose of the present study is to examine possible differences between orofacial migraine (OFM) and neurovascular orofacial pain (NVOP). Facial presentations of primary headache are comparable to primary headache disorders; but occurring in the V2 or V3 dermatomes of the trigeminal nerve. These were classified and recently published in the International Classification of Orofacial Pain, 1st edition (ICOP). A category in this classification is "orofacial pains resembling presentations of primary headaches," which encompasses OFM and NVOP. The differences between NVOP and OFM are subtle, and their response to therapy may be similar. While classified under two separate entities, they contain many features in common, suggesting a possible overlap between the two. Consequently, their separation into two entities warrants further investigations. We describe OFM and NVOP, and their pathophysiology is discussed. The similarities and segregating clinical signs and symptoms are analyzed, and the possibility of unifying the two entities is debated.

Tentorial ectopic schwannoma: A case report and literature review

Schwannomas arising within the central nervous system unrelated to a major cranial nerve rarely originate from the dura, particularly the tentorium. Hereby, the reported case is a 39-year-old female with blurred vision in her right eye for 1 month who was diagnosed with tentorial ectopic schwannoma. The tumor was almost totally resected through a posterior median incision approach without any neurological deficits. The clinical presentations and radiographic findings of such cases are discussed in the article.

Vagus Nerve Stimulation: A Personalized Therapeutic Approach for Crohn's and Other Inflammatory Bowel Diseases

Inflammatory bowel diseases, including Crohn's disease and ulcerative colitis, are incurable autoimmune diseases characterized by chronic inflammation of the gastrointestinal tract. There is increasing evidence that inappropriate interaction between the enteric nervous system and central nervous system and/or low activity of the vagus nerve, which connects the enteric and central nervous systems, could play a crucial role in their pathogenesis. Therefore, it has been suggested that appropriate neuroprosthetic stimulation of the vagus nerve could lead to the modulation of the inflammation of the gastrointestinal tract and consequent long-term control of these autoimmune diseases. In the present paper, we provide a comprehensive overview of (1) the cellular and molecular bases of the immune system, (2) the way central and enteric nervous systems interact and contribute to the immune responses, (3) the pathogenesis of the inflammatory bowel disease, and (4) the therapeutic use of vagus nerve stimulation, and in particular, the transcutaneous stimulation of the auricular branch of the vagus nerve. Then, we expose the working hypotheses for the modulation of the molecular processes that are responsible for intestinal inflammation in autoimmune diseases and the way we could develop personalized neuroprosthetic therapeutic devices and procedures in favor of the patients.

A importância da abordagem dos distúrbios do sono no tratamento da enxaqueca

Resumo A enxaqueca ou migrânea, é uma das queixas mais comuns na prática clínica da neurologia. É multifatorial, sendo a insônia um fator de predisposição presente em quase 50% dos casos. A fisiopatologia da migrânea é complexa e envolve alterações em diversas áreas do SNC e que encontram vias comuns com os distúrbios do sono. Entre elas, conexões hipotalâmicas, hormônios e neuropeptídeos, como orexias e monoaminérgicos. Além disso, outros distúrbios do sono específicos se relacionam com a migrânea. Atualmente, o tratamento é individualizado e além de medidas medicamentosas, é proposto mudanças nos hábitos de vida e adequações do sono. Diante disso, é uma oportunidade terapêutica a associação entre sono e enxaqueca e isso pode ser feito com base em uma abordagem clínica detalhada durante a consulta.

New insight into DAVF pathology—Clues from meningeal immunity

In recent years, with the current access in techniques, studies have significantly advanced the knowledge on meningeal immunity, revealing that the central nervous system (CNS) border acts as an immune landscape. The latest concept of meningeal immune system is a tertiary structure, which is a comprehensive overview of the meningeal immune system from macro to micro. We comprehensively reviewed recent advances in meningeal immunity, particularly the new understanding of the dural sinus and meningeal lymphatics. Moreover, based on the clues from the meningeal immunity, new insights were proposed into the dural arteriovenous fistula (DAVF) pathology, aiming to provide novel ideas for DAVF understanding.

A Review of Current Perspectives on Facial Presentations of Primary Headaches

Orofacial pain (OFP) has recently been classified and subdivided into a number of groups, similar to headache disorders in the International Classification of Headache Disorders (ICHD). A novel group of OFP has been established whose major feature is that they resemble primary headache disorders occurring in the V2 or V3 dermatomes. These follow the clinical criteria and associated symptoms of the eponymous headache syndromes. Following the recent International Classification of Orofacial Pain (ICOP), three types are differentiated: Headache which spread into the face (type 1), facial pain which replaced headache but maintained the same characteristics and associated symptoms of the former headache (type 2), and de-novo orofacial pain that resembles primary headache types without any involvement of the ophthalmic trigeminal branch (type 3). The epidemiology is unclear: type 1 and 2 are not exactly common, they certainly exist in a notable proportion of headache patients, whereas type 3 may be rather rare. Since effective treatment options are available, it is important for clinicians to recognize such syndromes early to avoid misdiagnosis and unnecessary treatment, which most of these patients still experience. This review gives an up-to-date summary of diagnosis, pathophysiology and treatment of attack-like non-dental facial pain disorders.

Torcular pseudomass in newborns and its association with delivery: follow up or leave it alone?

PURPOSE

The cranial epidural space (ES) is a potential space and is not generally recognized unless there is underlying pathology. With MRI in newborns, we have frequently observed T2 hyperintense thickening of the ES posterior to the confluence of sinuses, also referred to as "torcular pseudomass" (TP). We aim to identify the frequency of TP and possible associations with delivery.

METHODS

Retrospectively, brain MRIs of 194 neonates obtained within the first 2 weeks of life were evaluated. If TP was present, imaging characteristics and thickness were assessed by two observers, using fat-suppressed T2WI/FLAIR, T1WI, and SWI. Exclusion criteria were motion artifact, lack of sagittal T2WI, and lack of clinical data. Medical records were evaluated for demographic and clinical data. Follow-up exams were evaluated if available. Patients with TP and without were compared using Student t and chi-square tests.

RESULTS

TP was present in 64/158 (40%). No difference was found between the groups regarding sex, gestational age, birth weight, delivery type, fetal presentation during delivery, birth difficulty, and neurological sequelae (p > 0.05). Eight patients with TP underwent follow-up imaging, and in 6/8, TP completely resolved. Two patients showed persistent TP, improving from 3.2 to 1 mm in one child and from 3.2 to 2.8 mm in the other within a week.

CONCLUSION

TP frequently occurs in early newborns. TP does not appear to be associated with factors related to delivery, shows complete resolution in most cases with a follow-up, and is likely of no clinical importance.

Presynaptic Interactions between Trigeminal and Cervical Nociceptive Afferents Supplying Upper Cervical Lamina I Neurons

Cervical and trigeminal afferents innervate neighboring cranial territories, and their convergence on upper cervical dorsal horn neurons provides a potential substrate for pain referral in primary headache syndromes. Lamina I neurons are central to this mechanism, as they relay convergent nociceptive input to supraspinal pain centers. Unfortunately, little is known about the interactions between trigeminal and cervical afferents supplying Lamina I neurons. Here, we used rats of both sexes to show that cervical and trigeminal afferents interact via presynaptic inhibition, where monosynaptic inputs to Lamina I neurons undergo unidirectional as well as reciprocal presynaptic control. This means that afferent-driven presynaptic inhibition shapes the way trigeminal and cervical Aδ-fiber and C-fiber input reaches Lamina I projection neurons (PNs) and local-circuit neurons (LCNs). We propose that this inhibition provides a feedforward control of excitatory drive to Lamina I neurons that regulates their convergent and cervical-specific or trigeminal-specific processing modes. As a consequence, disruption of the trigeminal and cervical afferent-driven presynaptic inhibition may contribute to development of primary headache syndromes.SIGNIFICANCE STATEMENT Cervical and trigeminal afferents innervate neighboring cranial territories, and their convergence on upper cervical dorsal horn neurons provides a potential substrate for pain referral in primary headache syndromes. Lamina I neurons are central to this mechanism as they relay convergent nociceptive input to supraspinal pain centers. Here, we show that cervical and trigeminal afferents interact via presynaptic inhibition, where inputs to Lamina I neurons undergo unidirectional as well as reciprocal control. The afferent-driven presynaptic inhibition shapes the trigeminocervical Aδ-fiber and C-fiber input to Lamina I neurons. This inhibition provides control of excitatory drive to Lamina I neurons that regulates their convergent and cervical-specific or trigeminal-specific processing modes. Disruption of this control may contribute to development of primary headache syndromes.

Intracranial Malignant Peripheral Nerve Sheath Tumors Not Associated with a Cranial Nerve: Systematic Review and Illustrative Case

OBJECTIVE

Primary intracranial malignant peripheral nerve sheath tumors (MPNSTs) not associated with cranial nerves are rare and aggressive neoplasms. The rarity of presentation has precluded rigorous analysis of diagnosis, risk factors, treatment, and survival. We analyzed every reported case through exhaustive literature review. In addition, we present our own experience managed with resection, radiotherapy, and first use of targeted therapy in a tumor of this type for a BRAF mutation identified during next-generation sequencing.

METHODS

Two databases, PubMed and Embase, and crossed references were queried for intracranial MPNSTs not associated with a cranial nerve. Extracted variables included demographics, risk factors, tumor characteristics, interventions, and outcomes. Univariate and multivariate analysis was performed to identify factors with survival benefit.

RESULTS

A total of 56 patients (including the present case) were included from 743 literature results. There was a male/female ratio of 1.5:1 and mean diagnosis age of 29.7 ± 21.8 years. Seventy-one percent of cases were sporadic and 23% neurofibromatosis type 1 related. Median survival was 29 ± 22.1 months with 1-year survival of 60%. Factors associated on univariate analysis with reduced survival were subtotal resection (P = 0.05), older age (P = 0.023), triton histology (P < 0.001), and early recurrence (≤6 months) (P = 0.018). On multivariate analysis, gross total resection reduced mortality risk (P = 0.011), whereas triton histology (P = 0.017) and infratentorial tumor location (P = 0.037) increased mortality.

CONCLUSIONS

We present a systematic review of intracranial MPNSTs not associated with a cranial nerve. These tumors have poor prognosis and benefit from aggressive resection, multimodal treatment, and close follow-up. Next-generation sequencing can show molecular alterations for potential targeted therapy.

Asystole during Onyx embolization of 64-year-old patient with dural arteriovenous fistula

Asystole or bradycardia is a relatively uncommon side effect seen in patients undergoing endovascular embolization using dimethylsulfoxide based liquid embolic agents. We present a case of a patient who underwent dural arteriovenous fistula embolization and experienced bradycardia during Onyx injection but was stabilized and the procedure was completed successfully.

Intra-arterial injection of lidocaine into middle meningeal artery to treat intractable headaches and severe migraine

BACKGROUND AND PURPOSE

We report the results of intra-arterial injection of lidocaine in the middle meningeal artery in patients with intractable headache or status migrainosus.

METHODS

We treated four patients with intra-arterial lidocaine (2 mg/ml) in doses up to 50 mg in each middle meningeal artery via a microcatheter bilaterally (except in one patient). In two patients with intractable headache, the daily maximum intensity of headache (graded by 11-point numeric rating scale) was recorded for 7 days postprocedure. In two patients with status migrainosus, migraine-related disability 3 months prior and after treatment using MIDAS (Migraine Disability Assessment) questionnaire was recorded.

RESULTS

Intra-arterial lidocaine reduced the headache intensity from 8/10 and 10/10 to 0/10 in the two patients with intractable headaches for 2 days (day 0 and day 1) postprocedure. Despite recurrence of headache on day 2, the intensity was less than preprocedure intensity up to the last day recorded (by 3 and 2 points on day 7). In the two patients with status migrainosus, there was immediate reduction in headache intensity following intra-arterial lidocaine. The post treatment 3-month MIDAS score was lower in both patients compared with pretreatment 3-month score; 3 versus 30 and 55 versus 90. Severe disability preprocedure by MIDAS was reduced to little or no disability postprocedure in one patient.

CONCLUSIONS

Intra-arterial lidocaine resulted in amelioration of headache in patients with intractable headache and those with status migrainosus with improvement lasting longer than the short half-life of lidocaine possibly related to central desensitization.

First documented case of intracranial falcine malignant peripheral nerve sheath tumor: illustrative case

BACKGROUND

The authors reported the first documented case of intracranial extraaxial nonneurofibromatosis type 1-related nontriton malignant peripheral nerve sheath tumor (MPNST) originating from the falx cerebri.

OBSERVATIONS

A 34-year-old man with headache, short-term memory deficit, postural instability, and blurred vision presented with a large heterogenous contrast-enhanced intraventricular cystic lesion originating from the free margin of the falx cerebri. The patient received surgery using the right posterior interhemispheric approach. Gross total resection was performed, and the inferior border of the falx cerebri was resected. The postoperative course was uneventful. Histological examination revealed hypercellular foci of neoplastic spindle cells with hyperchromatic and wavy nuclei. Hence, a diagnosis of MPNST was made based on concomitant immunochemistry findings, including mouse double minute 2 homolog focal positivity and geographic loss of H3K27me3. The patient received adjuvant radiotherapy, and recurrence was not observed.

LESSONS

Intracranial MPNSTs are extremely rare tumors, typically originating from the cranial nerves in the posterior cranial fossa. An even rarer variant of these tumors, referred to as malignant intracerebral nerve sheath tumors, may directly arise from the brain parenchyma. The authors reported the first case of an intracranial MPNST originating from the dura mater of the falx cerebri, acting as an extraaxial lesion with prevalent expansion in the right ventricle.

Intracranial nociception

Understanding intracranial nociceptive innervation is essential to understand the pathophysiology of headaches. Our knowledge about human intracranial nociception comes from sparse observations during neurosurgical procedures performed in awake patients, from human anatomical studies and from experimental studies in animals. In this article we review the anatomical and functional organization underlying nociceptive innervation. Intracranial nociception is mainly mediated by the trigeminal system, except in the posterior cranial fossa that is innervated by the first cervical roots. For decades, the dura mater, its vessels and major cerebral blood vessels were considered as the only intracranial pain-sensitive structures. Recent animal and human studies have suggested that smaller brain arteries and potentially pia mater might also be pain sensitive. Nociceptive neurons innervating intracranial blood vessels project via the ophthalmic division (V1) to the trigeminal ganglion and store several neurotransmitters including glutamate, substance P and calcitonin gene-related peptide (CGRP). The trigeminal ganglion, root and brainstem nuclei have a specific topographic and functional somatotopy. Progressive transition between the trigeminal spinal nucleus and the dorsal horn of the cervical spinal cord, and convergence of nociceptive inputs from the face, intracranial structures and the occipital area on the so-called "trigemino-cervical complex" may explain some headache features, relations between facial and occipital pain, and efficacy of occipital nerve stimulation in headache. The specific anatomic organization of the trigeminal system, from the primary-order neuron in the trigeminal ganglion, to the second-order neuron is the trigeminal nuclei, may explain a part of the various characteristics of headaches.

Processing of trigeminocervical nociceptive afferent input by neuronal circuity in the upper cervical lamina I

ABSTRACT

Afferents from the C2 spinal nerve (SN) and trigeminal nerve (TN) innervate neighboring cranial territories, and their convergence on the upper cervical dorsal horn neurons represents neural substrate of pain referral in primary headache disorders. Unfortunately, little is known about trigeminocervical input to the major spinal nociceptive projection area lamina I. Here, we used ex vivo brainstem-cervical cord preparation for the visually guided whole-cell recording from the upper cervical lamina I neurons. We show that 50% of them receive convergent monosynaptic input from both nerves, whereas 35% and 11% of neurons receive specific supply from the C2 SN and TN, respectively. Altogether, 10 distinct patterns of synaptic input from the C2 SN and TN to lamina I neurons could be identified. Although stimulation of both nerves evoked excitatory/inhibitory responses, more numerous pure inhibitory inputs arose from the TN. We show that cervical and trigeminal nociceptors converge on to lamina I projection and inhibitory neurons. Thus, trigeminocervical input in lamina I is processed in both nerve-specific and convergent circuitries. Afferent convergence on to inhibitory interneurons serves as a feedforward mechanism balancing excitatory drive to projection neurons. Disruption of this balance may cause pain in primary headache syndromes.

Meningeal immunity: Structure, function and a potential therapeutic target of neurodegenerative diseases

Meningeal immunity refers to immune surveillance and immune defense in the meningeal immune compartment, which depends on the unique position, structural composition of the meninges and functional characteristics of the meningeal immune cells. Recent research advances in meningeal immunity have demonstrated many new ways in which a sophisticated immune landscape affects central nervous system (CNS) function under physiological or pathological conditions. The proper function of the meningeal compartment might protect the CNS from pathogens or contribute to neurological disorders. Since the concept of meningeal immunity, especially the meningeal lymphatic system and the glymphatic system, is relatively new, we will provide a general review of the meninges' basic structural elements, organization, regulation, and functions with regards to meningeal immunity. At the same time, we will emphasize recent evidence for the role of meningeal immunity in neurodegenerative diseases. More importantly, we will speculate about the feasibility of the meningeal immune region as a drug target to provide some insights for future research of meningeal immunity.

The trigeminal system: The meningovascular complex- A review

Supratentorial sensory perception, including pain, is subserved by the trigeminal nerve, in particular, by the branches of its ophthalmic division, which provide an extensive innervation of the dura mater and of the major brain blood vessels. In addition, contrary to previous assumptions, studies on awake patients during surgery have demonstrated that the mechanical stimulation of the pia mater and small cerebral vessels can also produce pain. The trigeminovascular system, located at the interface between the nervous and vascular systems, is therefore perfectly positioned to detect sensory inputs and influence blood flow regulation. Despite the fact that it remains only partially understood, the trigeminovascular system is most probably involved in several pathologies, including very frequent ones such as migraine, or other severe conditions, such as subarachnoid haemorrhage. The incomplete knowledge about the exact roles of the trigeminal system in headache, blood flow regulation, blood barrier permeability and trigemino-cardiac reflex warrants for an increased investigation of the anatomy and physiology of the trigeminal system. This translational review aims at presenting comprehensive information about the dural and brain afferents of the trigeminovascular system, in order to improve the understanding of trigeminal cranial sensory perception and to spark a new field of exploration for headache and other brain diseases.

Sphenopalatine ganglion block: Intranasal transmucosal approach for anterior scalp blockade - A prospective randomized comparative study

Background and Aims:

Peripheral nerve blocks in neurosurgical practice attenuate most stressful responses like pin insertion, skin, and dural incision. Scalp block is conventionally the blockade of choice. Further studies for less invasive techniques are required. Intranasal transmucosal block of the sphenopalatine ganglion has shown promising results in patients with chronic headache and facial pain. The primary objective of our study was to compare the gold standard scalp block and bilateral sphenopalatine ganglion block (nasal approach) for attenuation of hemodynamic response to pin insertion. Secondary objectives included hemodynamic response to skin and dural incision.

Material and Methods:

After IRB approval and informed consent, a prospective randomized comparative study was carried out on 50 adult patients undergoing elective supratentorial surgery. The hemodynamic response to pin insertion, skin incision, and dural incision was noted in both the groups. The data was analyzed with NCSS version 9.0 statistical software.

Results:

The HR and MAP were comparable between the groups. Following dural incision MAP was significantly lower at 1,2,3,4,5 and 10 min in group SPG whereas in group S it was significantly lower at 1 and 2min. (P = 0.02 at T1, P = 0.03 at T2).

Conclusions:

Concomitant use of bilateral SPG block with general anesthesia is an effective and safe alternative technique to scalp blockade for obtundation of hemodynamic responses due to noxious stimulus during craniotomy surgeries.

A Rare Case of Schwannoma Arising from the Dura Mater of the Petrosal Surface in the Posterior Cranial Fossa

BACKGROUND

An intracranial schwannoma originating in the dura mater is extremely rare. Herein, we report a case of schwannoma arising from the dura mater of the petrosal surface in the posterior cranial fossa.

CASE DESCRIPTION

A 48-year-old man presented with slight gait disturbance and papilledema. Magnetic resonance imaging showed a T1- and T2-weighted mixed-intensity extra-axial tumor, approximately 4 cm in the maximum diameter with multiple small cysts, in the left posterior cranial fossa. The tumor was heterogeneously enhanced with gadolinium. Operative findings via a lateral suboccipital approach revealed that the tumor did not adhere to any cranial nerves but to the dura mater of the petrosal surface. The tumor was completely excised without any neurologic deficits, and the histologic diagnosis was schwannoma.

CONCLUSIONS

The operative and postoperative findings suggested that the schwannoma originated in the meningeal branch of the lower cranial nerves or upper cervical nerves in the dura mater of the petrosal surface in the posterior cranial fossa.

The Five Diaphragms in Osteopathic Manipulative Medicine: Neurological Relationships, Part 1

In osteopathic manual medicine (OMM), there are several approaches for patient assessment and treatment. One of these is the five diaphragm model (tentorium cerebelli, tongue, thoracic outlet, diaphragm, and pelvic floor), whose foundations are part of another historical model: respiratory-circulatory. The myofascial continuity, anterior and posterior, supports the notion the human body cannot be divided into segments but is a continuum of matter, fluids, and emotions. In this first part, the neurological relationships of the tentorium cerebelli and the lingual muscle complex will be highlighted, underlining the complex interactions and anastomoses, through the most current scientific data and an accurate review of the topic. In the second part, I will describe the neurological relationships of the thoracic outlet, the respiratory diaphragm and the pelvic floor, with clinical reflections. In literature, to my knowledge, it is the first time that the different neurological relationships of these anatomical segments have been discussed, highlighting the constant neurological continuity of the five diaphragms.

Greater Occipital Nerve Block as a Tool to Diagnose Spontaneous Intracranial Hypotension Before Epidural Blood Patch: A Case Report

Spontaneous intracranial hypotension (SIH) has been increasingly characterized in recent years. A definitive diagnostic algorithm remains controversial because several symptoms are often found to be nonspecific. When neuroimaging fails to identify a cerebrospinal fluid leak and symptoms are atypical, an epidural blood patch (EBP) may be performed but not without risks. Our case shows how greater occipital nerve block (GONB) can expedite SIH diagnosis in a man with atypical presentation by reducing the sensory input from the posterior cranial fossa. The relief provided by GONB allowed to diagnose SIH promptly and the patient underwent a curative EBP.

Caffeine and Primary (Migraine) Headaches-Friend or Foe?

Background: The actions of caffeine as an antagonist of adenosine receptors have been extensively studied, and there is no doubt that both daily and sporadic dietary consumption of caffeine has substantial biological effects on the nervous system. Caffeine influences headaches, the migraine syndrome in particular, but how is unclear. Materials and Methods: This is a narrative review based on selected articles from an extensive literature search. The aim of this study is to elucidate and discuss how caffeine may affect the migraine syndrome and discuss the potential pathophysiological pathways involved. Results: Whether caffeine has any significant analgesic and/or prophylactic effect in migraine remains elusive. Neither is it clear whether caffeine withdrawal is an important trigger for migraine. However, withdrawal after chronic exposure of caffeine may cause migraine-like headache and a syndrome similar to that experienced in the prodromal phase of migraine. Sensory hypersensitivity however, does not seem to be a part of the caffeine withdrawal syndrome. Whether it is among migraineurs is unknown. From a modern viewpoint, the traditional vascular explanation of the withdrawal headache is too simplistic and partly not conceivable. Peripheral mechanisms can hardly explain prodromal symptoms and non-headache withdrawal symptoms. Several lines of evidence point at the hypothalamus as a locus where pivotal actions take place. Conclusion: In general, chronic consumption of caffeine seems to increase the burden of migraine, but a protective effect as an acute treatment or in severely affected patients cannot be excluded. Future clinical trials should explore the relationship between caffeine withdrawal and migraine, and investigate the effects of long-term elimination.

Aura and Head pain: relationship and gaps in the translational models

Migraine is a complex brain disorder and initiating events for acute attacks still remain unclear. It seems difficult to explain the development of migraine headache with one mechanism and/or a single anatomical location. Cortical spreading depression (CSD) is recognized as the biological substrate of migraine aura and experimental animal studies have provided mechanisms that possibly link CSD to the activation of trigeminal neurons mediating lateralized head pain. However, some CSD features do not match the clinical features of migraine headache and there are gaps in translating CSD to migraine with aura. Clinical features of migraine headache and results from research are critically evaluated; and consistent and inconsistent findings are discussed according to the known basic features of canonical CSD: typical SD limited to the cerebral cortex as it was originally defined. Alternatively, arguments related to the emergence of SD in other brain structures in addition to the cerebral cortex or CSD initiated dysfunction in the thalamocortical network are proposed. Accordingly, including thalamus, particularly reticular nucleus and higher order thalamic nuclei, which functions as a hub connecting the visual, somatosensory, language and motor cortical areas and subjects to modulation by brain stem projections into the CSD theory, would greatly improve our current understanding of migraine.

Tentorial Venous Anatomy: Cadaveric and Radiographic Study with Discussion of Origin and Surgical Significance

BACKGROUND

Described variations of tentorial venous anatomy impact surgical sectioning of the tentorium in skull base approaches; however, described configurations do not consistently explain postoperative complications. To understand the outcomes of 2 clinical cases we studied the tentorial venous anatomy of 2 cadavers.

METHODS

The venous anatomy of the tentorium isolated in 2 uninjected fresh cadaver head specimens with preserved bridging veins was observed by transillumination before and after methylene blue injection of the dural sinuses and tentorial veins. Our findings in cadavers were applied to explain the clinical and radiologic (magnetic resonance imaging and computed tomographic venography) findings in the 2 cases presented.

RESULTS

A consistent transtentorial venous system, arising from transverse and straight sinuses, communicating with supra- and infratentorial bridging veins was seen in the cadaver and patient radiography (magnetic resonance imaging and computed tomographic venography). Our first patient had a cerebellar venous infarct from compromise of the venous drainage from the adjacent brain after ligation of a temporal lobe bridging vein to the tentorium. Our second patient suffered no clinical effects from bilateral transverse sinus occlusion due to drainage through the accessory venous system within the tentorium.

CONCLUSIONS

Herein, we elaborate on transtentorial venous anatomy. These veins, previously reported to obliterate in completed development of the tentorium, remain patent with consistent observed configuration. The same transtentorial venous system was observed in both cases and provided insight to their outcomes. These findings emphasize the importance of the transtentorial venous system physiologically and in surgical approaches.

The Tentorium Cerebelli: A Comprehensive Review Including Its Anatomy, Embryology, and Surgical Techniques

The tentorium cerebelli functions as a partition, dispelling the burden of weight from supratentorial structures upon inferior brain matter. Clinicians and neurosurgeons, when assessing pathological findings, should have knowledge regarding the tentorium cerebelli anatomy. This work of literature is a comprehensive review of the tentorium cerebelli, including its anatomy, embryology, and clinical and surgical implications. The evolutionary pattern demonstrates sequential stages to higher mammalian lineage. An understanding of the complexity of the neurovascular structures and the anatomy of the tentorium cerebelli is crucial for surgical procedures by neurosurgeons.

Advances in Meningeal Immunity

The central nervous system (CNS) is an immunologically specialized tissue protected by a blood-brain barrier. The CNS parenchyma is enveloped by a series of overlapping membranes that are collectively referred to as the meninges. The meninges provide an additional CNS barrier, harbor a diverse array of resident immune cells, and serve as a crucial interface with the periphery. Recent studies have significantly advanced our understanding of meningeal immunity, demonstrating how a complex immune landscape influences CNS functions under steady-state and inflammatory conditions. The location and activation state of meningeal immune cells can profoundly influence CNS homeostasis and contribute to neurological disorders, but these cells are also well equipped to protect the CNS from pathogens. In this review, we discuss advances in our understanding of the meningeal immune repertoire and provide insights into how this CNS barrier operates immunologically under conditions ranging from neurocognition to inflammatory diseases.

Macroscopic Innervation of the Dura Mater Covering the Middle Cranial Fossa in Humans Correlated to Neurovascular Headache

The trigeminovascular system within the cranial dura mater is a possible cause of headaches. The aim of this study is to investigate macroscopically dural innervation around the middle meningeal artery (MMA) in the middle cranial fossa. Forty-four sides of the cranial dura overlying the skull base obtained from 24 human cadavers were stained using Sihler’s method. Overall, the nervus spinosus (NS) from either the maxillary or mandibular trigeminal divisions ran along the lateral wall of the middle meningeal vein rather than that of the MMA. Distinct bundles of the NS running along the course of the frontal branches of the MMA were present in 81.8% of cases (N = 36). Others did not form dominant nerve bundles, instead giving off free nerve endings along the course of the MMA or dural connective tissue. The distribution of these nerve endings was similar to that of the course of the frontal, parietal and petrosal branches of the MMA (11.4%). The others were not restricted to a perivascular plexus, crossing the dural connective tissues far from the MMA (6.8%). These findings indicate that the NS generally travels alongside the course of the frontal branches of the MMA and terminates in the vicinity of the pterion.

Designing a pain management protocol for craniotomy: A narrative review and consideration of promising practices

BACKGROUND

Craniotomy is a relatively common surgical procedure with a high incidence of postoperative pain. Development of standardized pain management and enhanced recovery after surgery (ERAS) protocols are necessary and crucial to optimize outcomes and patient satisfaction and reduce health care costs.

METHODS

This work is based upon a literature search of published manuscripts (between 1996 and 2017) from Pubmed, Cochrane Central Register, and Google Scholar. It seeks to both synthesize and review our current scientific understanding of postcraniotomy pain and its part in neurosurgical ERAS protocols.

RESULTS

Strategies to ameliorate craniotomy pain demand interventions during all phases of patient care: preoperative, intraoperative, and postoperative interventions. Pain management should begin in the perioperative period with risk assessment, patient education, and premedication. In the intraoperative period, modifications in anesthesia technique, choice of opioids, acetaminophen and nonsteroidal anti-inflammatory drugs (NSAIDs), regional techniques, dexmedetomidine, ketamine, lidocaine, corticosteroids, and interdisciplinary communication are all strategies to consider and possibly deploy. Opioids remain the mainstay for pain relief, but patient-controlled analgesia, NSAIDs, standardization of pain management, bio/behavioral interventions, modification of head dressings as well as patient-centric management are useful opportunities that potentially improve patient care.

CONCLUSIONS

Future research on mechanisms, predictors, treatments, and pain management pathways will help define the combinations of interventions that optimize pain outcomes.

Posterior meningeal artery DMSO injection resulting in reproducible asystole prior to Onyx therapy of a dural arteriovenous fistula: a previously undescribed variant of the trigeminocardiac reflex or a new phenomenon?

We describe a case of reproducible asystole during endovascular treatment of a posterior fossa dural arteriovenous fistula. Catheterisation of the posterior meningeal artery, a branch of the vertebral artery in this patient, followed by dimethyl sulfoxide injection prior to Onyx administration resulted in two episodes of asystole.To the best of our knowledge, this is the first reported case of asystole occurring during endovascular intervention in the posterior meningeal artery. This may represent a previously undescribed variant of the trigemino-cardiac reflex (TGCR) caused by chemical stimulation of small areas of trigeminally innervated posterior fossa dura. Alternatively, this may represent a newly identified phenomenon with chemical stimulation of regions of posterior fossa dura innervated by branches of the vagus nerve leading to increased parasympathetic activity and resultant asystole.In either case, it is important to recognise the potential for such episodes in this vascular territory to allow case planning and management.

Visualization of the tentorial innervation of human dura mater

Posterior projections of the ophthalmic division of the trigeminal nerve (the ophthalmic nerve) are distributed in the tentorium cerebelli as recurrent meningeal branches. We investigated the morphological tentorial distribution of the ophthalmic nerve. Fifty-two sides of the tentorium cerebelli and adjacent dura mater obtained from 29 human specimens were stained using Sihler's method to examine the nerve fibres in the dural sheets. The innervation patterns of the tentorium cerebelli were classified into the following four types according to their distributions: Type 1, where nerve fibres projected to both the straight and transverse sinuses; Type 2, where nerve fibres projected only to the transverse sinus and lateral convexity; Type 3, where nerve fibres projected medially only to the straight sinus and the posterior part of the falx cerebri; and Type 4, where the nerve fibres terminated within the tentorium cerebelli. Images of the tentorium cerebelli were superimposed to identify areas of dense innervation. The incidence rates of Types 1-4 were 71.2% (n = 37), 21.2% (n = 11), 3.8% (n = 2) and 3.8% (n = 2), respectively. More branches of nerve fibres traversed towards the transverse sinus posterolaterally than towards the straight sinus medially. The space between the anterior half of the straight sinus and the medial tentorial notch can be considered a safe surgical area where innervation is scarce. The posterior part of the falx cerebri was innervated by the ophthalmic nerve that traversed to the straight sinus. The parietal branches of the middle meningeal artery in the lateral convexity that were projected orthogonally by the ophthalmic nerve traversed the transverse sinus, implicating their vulnerability and possible sensitivity under physiological or neurosurgical conditions. This study has revealed the macroscopic tentorial innervation of the dura mater in humans, which could be useful information for both neurosurgeons and neurologists.

Facial presentations of primary headache disorders

Background

Many patients with mid-face or lower face craniofacial pain are diagnosed, based on accompanying signs and symptoms and features other than location, as either atypical migraines or atypical TACs. Distinguishing features of headache disorders as a cause of facial pain include the temporal pattern of pain, associated symptoms including light and sound sensitivity and nausea, cranial autonomic symptoms, and the lack of local triggering among others.

Results

An intraoral neurovascular pain has been observed, and was termed neurovascular orofacial pain (NVOP). Due to its location, and signs imitating dental pulpitis, it has great diagnostic and therapeutic importance for differentiating NVOP from dental pathology. The hypothesized mechanism is neurogenic inflammatory activation within the space confined by dentine around the dental pulp, expressed in strong paroxysmal pain and typical allodynia to cold foods.

Conclusion

Facial manifestations of headache disorders and primary facial pain disorders share common trigeminal nerve input, yet they are highly distinct disorders. Somatotopic segregation may occur at the level of the trigeminal nucleus, thalamus, and somatosensory cortex, and distinct ionic or neurochemical signaling pathways may be involved. Further investigation of facial presentations of headache disorders has the potential to provide new insight into the interface between headache and facial pain.

The continuity of the body: hypothesis of treatment of the five diaphragms

The diaphragm muscle should not be seen as a segment but as part of a body system. This muscle is an important crossroads of information for the entire body, from the trigeminal system to the pelvic floor, passing from thoracic diaphragm to the floor of the mouth: the network of breath. Viola Frymann first spoke of the treatment of three diaphragms, and more recently four diaphragms have been discussed. Current scientific knowledge has led to discussion of the manual treatment of five diaphragms. This article highlights the anatomic connections and fascial and neurologic aspects of the diaphragm muscle, with four other structures considered as diaphragms: that is, the five diaphragms. The logic of the manual treatment proposed here is based on a concept and diagnostic work that should be the basis for any area of the body: The patient never just has a localized symptom but rather a system that adapts to a question.

Vertical osteoconductivity of sputtered hydroxyapatite-coated mini titanium implants after dura mater elevation: Rabbit calvarial model

This study evaluated the quantity and quality of newly formed vertical bone induced by sputtered hydroxyapatite-coated titanium implants compared with sandblasted acid-etched implants after dura mater elevation. Hydroxyapatite-coated and non-coated implants (n = 20/group) were used and divided equally into two groups. All implants were randomly placed into rabbit calvarial bone (four implants for each animal) emerging from the inferior cortical layer, displacing the dura mater 3 mm below the original bone. Animals were sacrificed at 4 (n = 5) and 8 (n = 5) weeks post-surgery. Vertical bone height and area were analyzed histologically and radiographically below the original bone. Vertical bone formation was observed in both groups. At 4 and 8 weeks, vertical bone height reached a significantly higher level in the hydroxyapatite compared with the non-coated group (p < 0.05). Vertical bone area was significantly larger in the hydroxyapatite compared with the non-coated group at 4 and 8 weeks (p < 0.05). This study indicates that vertical bone formation can be induced by dura mater elevation and sputtered hydroxyapatite coating can enhance vertical bone formation.

Innervation of the cerebral dura mater

The trigemino-cardiac reflex during Onyx embolization for dural arteriovenous fistula may be caused by mechanical or chemical stimulus to the terminals of the unencapsulated Ruffini-like receptors stemming from A-axons in the dural connective tissue at sites of dural arteries and sinuses. Slow A (Aδ) and fast A (Aβ) neurons may play a role in the stimulus afferent pathway due to their higher mechanosensitivity and chemosensitivity. These afferent pathway nerves are cholinergic innervations of the dura mater, which also contains vasoactive neuropeptides such as calcitonin gene-related peptide, substance P, and neurokinin A. Stimulation of meningeal sensory fibres can evoke cerebral vasodilation through the peripheral release of neuropeptides, which play a role in headache pathogenesis. These myelinated A-fibers terminate in the deep part (laminae III-V) of the spinal dorsal horn. Its efferent pathway has been defined as the acetylcholinergic vagus nerve. The A11 nucleus, located in the posterior hypothalamus, providing the only known source of descending dopaminergic innervation for the spinal grey matter, can inhibit the neurons in the spinal dorsal horn.

Dural sinus filling defect: intrasigmoid encephalocele

Filling defects of dural venous sinuses are considered to be a challenging problem especially in case of symptomatic patients. Many lesions have to be ruled out such as sinus thrombosis, arachnoid granulations and tumours. Encephalocele into dural sinus is also a rare cause of these filling defects of dural sinuses. Here, we report an extremely rare case with spontaneous occult invagination of temporal brain tissue into the left sigmoid sinus and accompanying cerebellar ectopia.

Recurrent and self-remitting sixth cranial nerve palsy: pathophysiological insight from skull base chondrosarcoma

Palsy of the abducens nerve is a neurological sign that has a wide range of causes due to the nerve's extreme vulnerability. Need of immediate neuroimaging is a matter of debate in the literature, despite the risks of delaying the diagnosis of a skull base tumor. The authors present 2 cases of skull base tumors in which the patients presented with recurrent and self-remitting episodes of sixth cranial nerve palsy (SCNP). In both cases the clinical history exceeded 1 year. In a 17-year-old boy the diagnosis was made because of the onset of headache when the tumor reached a very large size. In a 12-year-old boy the tumor was incidentally diagnosed when it was still small. In both patients surgery was performed and the postoperative course was uneventful. Pathological diagnosis of the tumor was consistent with that of a chondrosarcoma in both cases. Recurrent self-remitting episodes of SCNP, resembling transitory ischemic attacks, may be the presenting sign of a skull base tumor due to the anatomical relationships of these lesions with the petroclival segment of the sixth cranial nerve. Physicians should promptly recommend neuroimaging studies if SCNP presents with this peculiar course.

Anatomic connections of the diaphragm: influence of respiration on the body system

The article explains the scientific reasons for the diaphragm muscle being an important crossroads for information involving the entire body. The diaphragm muscle extends from the trigeminal system to the pelvic floor, passing from the thoracic diaphragm to the floor of the mouth. Like many structures in the human body, the diaphragm muscle has more than one function, and has links throughout the body, and provides the network necessary for breathing. To assess and treat this muscle effectively, it is necessary to be aware of its anatomic, fascial, and neurologic complexity in the control of breathing. The patient is never a symptom localized, but a system that adapts to a corporeal dysfunction.