Intracranial nociception

The Challenges in Clinical Diagnosis of Trigeminal Neuralgia: A Review

The lack of established laboratory tests or biomarkers for trigeminal neuralgia (TN) makes diagnosing this relatively rare condition extremely challenging. Trigeminal nerve compression observable on magnetic resonance imaging may indicate TN, but many patients do not have visible lesions or compression. In particular, TN may be confused with migraine, cluster headache, temporomandibular disorder, and other types of headache. An accurate diagnosis is imperative for proper treatment since these conditions do not respond to the same treatment. Many symptoms of these headaches can be vague or overlap, and clinicians depend in large measure on the subjective reports of their patients. Nevertheless, it is imperative to diagnose TN better, which can cause excruciating pain, reduce the quality of life, and even result in disability. It is possible that TN is underestimated.

A comprehensive analysis of patients with cerebral arteriovenous malformation with headache: assessment of risk factors and treatment effectiveness

BACKGROUND

Due to the high mortality and disability rate of intracranial hemorrhage, headache is not the main focus of research on cerebral arteriovenous malformation (AVM), so research on headaches in AVM is still scarce, and the clinical understanding is shallow. This study aims to delineate the risk factors associated with headaches in AVM and to compare the effectiveness of various intervention treatments versus conservative treatment in alleviating headache symptoms.

METHODS

This study conducted a retrospective analysis of AVMs who were treated in our institution from August 2011 to December 2021. Multivariable logistic regression analysis was employed to assess the risk factors for headaches in AVMs with unruptured, non-epileptic. Additionally, the effectiveness of different intervention treatments compared to conservative management in alleviating headaches was evaluated through propensity score matching (PSM).

RESULTS

A total of 946 patients were included in the analysis of risk factors for headaches. Multivariate logistic regression analysis identified that female (OR 1.532, 95% CI 1.173-2.001, p = 0.002), supply artery dilatation (OR 1.423, 95% CI 1.082-1.872, p = 0.012), and occipital lobe (OR 1.785, 95% CI 1.307-2.439, p < 0.001) as independent risk factors for the occurrence of headaches. There were 443 AVMs with headache symptoms. After propensity score matching, the microsurgery group (OR 7.27, 95% CI 2.82-18.7 p < 0.001), stereotactic radiosurgery group(OR 9.46, 95% CI 2.26-39.6, p = 0.002), and multimodality treatment group (OR 8.34 95% CI 2.87-24.3, p < 0.001) demonstrate significant headache relief compared to the conservative group. However, there was no significant difference between the embolization group (OR 2.24 95% CI 0.88-5.69, p = 0.091) and the conservative group.

CONCLUSIONS

This study identified potential risk factors for headaches in AVMs and found that microsurgery, stereotactic radiosurgery, and multimodal therapy had significant benefits in headache relief compared to conservative treatment. These findings provide important guidance for clinicians when developing treatment options that can help improve overall treatment outcomes and quality of life for patients.

Neurovascular Compression-Induced Intracranial Allodynia May Be the True Nature of Migraine Headache: an Interpretative Review

PURPOSE OF REVIEW

Surgical deactivation of migraine trigger sites by extracranial neurovascular decompression has produced encouraging results and challenged previous understanding of primary headaches. However, there is a lack of in-depth discussions on the pathophysiological basis of migraine surgery. This narrative review provides interpretation of relevant literature from the perspective of compressive neuropathic etiology, pathogenesis, and pathophysiology of migraine.

RECENT FINDINGS

Vasodilation, which can be asymptomatic in healthy subjects, may produce compression of cranial nerves in migraineurs at both extracranial and intracranial entrapment-prone sites. This may be predetermined by inherited and acquired anatomical factors and may include double crush-type lesions. Neurovascular compression can lead to sensitization of the trigeminal pathways and resultant cephalic hypersensitivity. While descending (central) trigeminal activation is possible, symptomatic intracranial sensitization can probably only occur in subjects who develop neurovascular entrapment of cranial nerves, which can explain why migraine does not invariably afflict everyone. Nerve compression-induced focal neuroinflammation and sensitization of any cranial nerve may neurogenically spread to other cranial nerves, which can explain the clinical complexity of migraine. Trigger dose-dependent alternating intensity of sensitization and its synchrony with cyclic central neural activities, including asymmetric nasal vasomotor oscillations, may explain the laterality and phasic nature of migraine pain. Intracranial allodynia, i.e., pain sensation upon non-painful stimulation, may better explain migraine pain than merely nociceptive mechanisms, because migraine cannot be associated with considerable intracranial structural changes and consequent painful stimuli. Understanding migraine as an intracranial allodynia could stimulate research aimed at elucidating the possible neuropathic compressive etiology of migraine and other primary headaches.

The putative role of neuroinflammation in the complex pathophysiology of migraine: From bench to bedside

The implications of neurogenic inflammation and neuroinflammation in the pathophysiology of migraine have been clearly demonstrated in preclinical migraine models involving several sites relevant in the trigemino-vascular system, including dural vessels and trigeminal endings, the trigeminal ganglion, the trigeminal nucleus caudalis as well as central trigeminal pain processing structures. In this context, a relevant role has been attributed over the years to some sensory and parasympathetic neuropeptides, in particular calcitonin gene neuropeptide, vasoactive intestinal peptide and pituitary adenylate cyclase-activating polypeptide. Several preclinical and clinical lines of evidence also support the implication of the potent vasodilator and messenger molecule nitric oxide in migraine pathophysiology. All these molecules are involved in vasodilation of the intracranial vasculature, as well as in the peripheral and central sensitization of the trigeminal system. At meningeal level, the engagement of some immune cells of innate immunity, including mast-cells and dendritic cells, and their mediators, has been observed in preclinical migraine models of neurogenic inflammation in response to sensory neuropeptides release due to trigemino-vascular system activation. In the context of neuroinflammatory events implicated in migraine pathogenesis, also activated glial cells in the peripheral and central structures processing trigeminal nociceptive signals seem to play a relevant role. Finally, cortical spreading depression, the pathophysiological substrate of migraine aura, has been reported to be associated with inflammatory mechanisms such as pro-inflammatory cytokine upregulation and intracellular signalling. Reactive astrocytosis consequent to cortical spreading depression is linked to an upregulation of these inflammatory markers. The present review summarizes current findings on the roles of immune cells and inflammatory responses in the pathophysiology of migraine and their possible exploitation in the view of innovative disease-modifying strategies.

Chronic craniomandibular pain after craniotomy: A long-term clinical study

OBJECTIVE

Chronic craniomandibular/cervical pain and temporomandibular disorders have not been studied in patients who had a craniotomy several years previously. The aim of the current clinical work was to address these issues.

METHODS

A total group of 150 ambulant patients who had a previous craniotomy was subclassified according to whether or not the temporalis muscle was manipulated.

RESULTS

The average incidence of multiple subsite regional head and neck pain was 69.3% a number of years after a craniotomy. Evidence of internal derangement of the temporomandibular joint was significantly higher in the group that required manipulation of the temporalis muscle during the procedure.

CONCLUSION

The pattern of chronic craniomandibular/cervical pain experienced years after a craniotomy supports the brain neuromatrix theory of pain.

A new concept of the fiber composition of cervical spinal dura mater: an investigation utilizing the P45 sheet plastination technique

Purpose

Few reports have been published regarding the microanatomy of the dura mater located at the craniovertebral junction (CVJ). In clinic, the precise microanatomy of the CVJ dura mater would be taken into account, for reducing surgical complications and ineffective surgical outcomes. The main objective of the present investigation was to further elucidate the fiber composition and sources of the cervical spinal dura mater.

Methods

The formalin-fixed adult head and neck specimens (n = 21) were obtained and P45 plastinated section method was utilized for the present study. The fibers of the upper cervical spinal dura mater (SDM) were examined in the P45 sagittal sections in the CVJ area. All photographic documentation was performed via a Canon EOS 7D Mark camera.

Results

The posterior wall of the SDM sac at CVJ was found to be composed of stratified fibers, which are derived from three sources: the cerebral dura mater, the occipital periosteum, and the myodural bridge (MDB). The proper layer of the cerebral dura mater passes over the brim of the foramen magnum and enters the vertebral canal to form the inner layer of the SDM, and the fibers originating from the periosteum of the brim of the foramen magnum form the middle layer. The fibers of the MDB are inserted into the SDM and form its outer layer. It was found that the total number of fibers from each origin varied in humans.

Conclusion

At the CVJ, the posterior wall of the SDM is a multi-layered structure composed of three different originated fibers. The cerebral dura mater, the periosteum located at the brim of the foramen magnum, and MDB contribute to the formation of the SDM. The present study would be beneficial to the choice of surgical approach at the CVJ and the protection of the SDB.