A Secretory Vesicle Failure in Parkinson's Disease Occurs in Human Platelets.

OBJECTIVE: The presence of elevated dopamine (DA) and its major metabolites in the cytosol of neurons has been associated with their vulnerability in Parkinson's disease (PD). Over 99% of the cell's amines are confined to secretory vesicles (SVs), making these structures fundamental in the regulation of cytosolic DA levels. SVs of platelets use similar, if not the same mechanisms to accumulate serotonin in SVs as dopaminergic neurons do to store DA. Hence, any functional defects in platelets probably mirrors events in DA neurons. METHODS: We have isolated fresh platelets from the blood of 75 PD patients, 116 matched controls and 24 patients with Parkinsonism, assaying serotonin handling (basal content, accumulation, secretion and spontaneous leakage). RESULTS: We found a dramatic decrease in the serotonin content and uptake by SVs, as well as decreased thrombin-induced release by platelets from PD patients but not in those from most Parkinsonism cases. Platelets from PD patients also failed to retain serotonin in SVs. INTERPRETATION: These findings indicate a functional impairment in the handling of amines by SVs in PD patients. This defect may serve as a biomarker of PD, and the approach described here may be potentially used for the subclinical detection of PD and to establish a platform to assay disease modifying drugs. ANN NEUROL 2022.

Effectiveness and safety profile of greater occipital nerve blockade in cluster headache: a systematic review.

BACKGROUND: Greater occipital nerve (GON) blockade is a short-term preventive therapy for cluster headache (CH). We conducted a systematic review to evaluate the effectiveness and safety of GON blockade in patients with CH. METHODS: On 23 October 2020, we searched MEDLINE, Embase, Embase Classic, PsycINFO, CINAHL, CENTRAL and Web of Science databases from their inception date. Studies included participants with a CH diagnosis who received corticosteroid and local anaesthetic suboccipital region injections. Outcomes were change in the frequency/severity/duration of attacks; proportion of participants responding to treatment, time to attack freedom from an attack, change in attack bout length and/or the presence of adverse effects after GON blockade. Risk of bias was assessed with the Cochrane Risk of Bias V.2.0 (RoB2)/Risk of Bias in Non-randomized Studies - of Interventions (ROBINS- I) tools and a specific tool for case reports/series. RESULTS: Two RCTs, eight prospective and eight retrospective studies, and four case reports were included in the narrative synthesis. Every effectiveness study found a significant response in one or more of frequency/severity/duration of individual attacks or proportion of patients responding to treatment (47.8%-100.0%). There were five instances of potentially irreversible adverse effects. A higher injectate volume and use of concurrent prophylaxis may be associated with an increased likelihood of response. Methylprednisolone may have the best safety profile of available corticosteroids. DISCUSSION: GON blockade is safe and effective for CH prevention. Higher injectate volumes may improve likelihood of response, and the likelihood of serious adverse events may be reduced by using methylprednisolone. PROSPERO REGISTRATION NUMBER: CRD42020208435.

Erenumab in chronic migraine: Experience from a UK tertiary centre and comparison with other real-world evidence.

BACKGROUND AND PURPOSE: Chronic migraine is a highly disabling primary headache disorder that is the most common diagnosis of patients seen at tertiary headache centres. Typical oral preventive therapies are associated with many limitations that impact their therapeutic utility. Erenumab was the first available calcitonin gene-related peptide monoclonal antibody in the UK. It had proven efficacy in migraine prevention in clinical trials and limited real-world data in tertiary settings. METHODS: We audited our first 92 patients (n = 73 females) with severely disabling chronic migraine who were given monthly erenumab 70 mg sc for 6 months between December 2018 and December 2019. RESULTS: At 3 months, monthly migraine days were significantly reduced by a median of 4 days, and all other variables also showed significant improvement. The improvement was not affected by baseline analgesic use status. More than half of our patients experienced a clinically meaningful improvement in migraine days. No serious adverse events were reported. CONCLUSIONS: Our real-world data with erenumab demonstrate it is effective and well tolerated in managing patients with chronic migraine in a tertiary care setting.

Targets for migraine treatment: beyond calcitonin gene-related peptide.

PURPOSE OF REVIEW: Despite the development of several medications for the acute and preventive treatment of migraine, there are still many patients in whom lack of efficacy, tolerability, interactions or contraindications make other options necessary. CGRP-based drugs have opened the door to a new era of migraine-targeted treatments. Beyond CGRP, there are other promising targets covered here. RECENT FINDINGS: For the acute treatment of migraine, 5-HT1F receptor agonists, ditans, are now available. Unlike triptans, 5-HT1B/1D receptor agonists, cardiovascular disease is not a contraindication for the use of ditans. The first study on a monoclonal antibody targeting PAC1 receptor was negative, although this may not be the end for the pituitary adenylate cyclase-activating polypeptide (PACAP) pathway as a target. SUMMARY: Following positive phase-III clinical trials, lasmiditan is the first ditan to be FDA-approved. PACAP has experimental evidence suggesting a role in migraine pathophysiology. As for CGRP, the presence of PACAP in key migraine structures along with positive provocative tests for both PACAP-38 and PACAP-27 indicate this pathway may still be a pharmacological target. Glutamate-based targets have long been considered in migraine. Two clinical trials with memantine, an NMDA-R antagonist, for the preventive treatment of migraine have now been published. The hypothalamus has also been implicated in migraine pathophysiology: the potential role of orexins in migraine is discussed. Acid-sensing ion channels, as well as amylin-blocking drugs, may also become migraine treatments in the future: more research is warranted.

Indomethacin-responsive headaches-A narrative review.

BACKGROUND: Indomethacin is a nonsteroidal anti-inflammatory drug whose mechanism of action in certain types of headache disorders remains unknown. The so-called indomethacin-responsive headache disorders consist of a group of conditions with a very different presentation that have a particularly good response to indomethacin. The response is so distinct as to be used in the definition of two: hemicrania continua and paroxysmal hemicrania. METHODS: This is a narrative literature review. PubMed and the Cochrane databases were used for the literature search. RESULTS: We review the main pharmacokinetic and pharmacodynamics properties of indomethacin useful for daily practice. The proposed mechanisms of action of indomethacin in the responsive headache disorders, including its effect on cerebral blood flow and intracranial pressure, with special attention to nitrergic mechanisms, are covered. The current evidence for its use in primary headache disorders, such as some trigeminal autonomic cephalalgias, cough, hypnic, exertional or sexual headache, and migraine will be covered, as well as its indication for secondary headaches, such as those of posttraumatic origin. CONCLUSION: Increasing understanding of the mechanism(s) of action of indomethacin will enhance our understanding of the complex pathophysiology that might be shared by indomethacin-sensitive headache disorders.

Evolving options for the treatment of cluster headache.

PURPOSE OF REVIEW: Cluster headache is a neurological disorder that patients consider the most severe pain they experience. Recognizing new treatments provides opportunities to advance current management. RECENT FINDINGS: In contrast to the classic treatments, new options narrow in on the therapeutic target and are better tolerated. Calcitonin gene-related peptide (CGRP) pathway blockade with monoclonal antibodies (MABs), specifically the CGRP MAB galcanezumab, represents an important advance for episodic cluster headache, reducing the number of attacks during a bout. Neuromodulation strategies aimed at anatomical structures involved in the pathophysiology of cluster headache, such as the sphenopalatine ganglion and the vagus nerve, have proved effective in reducing the pain intensity and the number of attacks, and also to be safe and well tolerated. SUMMARY: Our understanding of the pathophysiology of cluster headache and its management continues to grow. Novel treatments have appeared from research, such as neuromodulation and CGRP monoclonal antibodies. Nonetheless, chronic cluster headache and designing trials that select the correct sham in evaluating devices remain challenging.

Targeting CGRP and 5-HT1F Receptors for the Acute Therapy of Migraine: A Literature Review.

OBJECTIVE: To review and highlight current literature on emerging acute migraine treatments, focusing on CGRP receptor antagonists, gepants, and 5-HT1F receptor agonists (ditans). BACKGROUND: Current acute migraine therapy consists of nonspecific analgesia and triptans. Limitations to these medicines, including lack of efficacy in many patients, side effects and the contraindication of triptans in patients with cardiovascular disease, suggest that there is an unmet need for new treatments. Studies of serotonin pharmacology led to the development of triptans, 5-HT1B/1D receptor agonists, some of which have actions at the 5-HT1F receptor. Exploration of the role of calcitonin gene-related peptide (CGRP) has resulted in the development of CGRP receptor antagonists. METHOD: The authors performed a literature search of Pubmed and Cochrane databases as well as reviewed abstracts presented at meetings: American Headache Society, American Academy of Neurology, European Headache Federation and the Migraine Trust International Symposium, as well as on-line sources. The authors briefly detail the relevant migraine pathophysiology pertaining to 5-HT1F receptor and the CGRP pathway relevant to acute therapies. Recent clinical trials of acute therapies in which 5-HT1F receptor agonists or CGRP receptor antagonists were studied are summarized. RESULTS: Two 5-HT1F receptor agonists have reached phase II clinical trials. One, lasmiditan, has completed 2 phase III clinical trials, demonstrating a significant effect for pain freedom and most bothersome symptom at 2 hours. Among the 6 gepants tested for the acute treatment of migraine to date, after issues for some of hepatic safety or efficacy, 2 CGRP receptor antagonists, rimegepant and ubrogepant, have completed phase III trials showing efficacy and safety. CONCLUSION: Current available therapies have either been nonspecific or had important limitations, including in patients with cardiovascular risk factors. Phase III clinical trials of lasmiditan, rimegepant and ubrogepant all met their primary endpoints, so the options for migraine-targeted acute therapy will likely soon increase.

Familial hemiplegic migraine.

Hemiplegic migraine consists of attacks of migraine with aura that includes reversible motor weakness. It is classified as familial or sporadic depending on the involvement or not of a first or second degree relative. The most described subtypes of familial hemiplegic migraine include FHM1, FHM2, and FHM3. These have been demonstrated to have a mutation in either CACNA1A, ATP1A2 or SCN1A, which encode different subunits of channels, involving P/Q-type calcium channel, Na/K pump and Na channel, respectively, located in neurons and glial cells. Mutations localized in different genes are defined as "other loci." Patients with a known mutation can have different genetic penetrance, and may present a more complex and disabling phenotype that develops earlier in life. The clinical manifestations can be similar in the three mutations, including neurologic comorbidities other than muscular weakness, such as episodes of loss of consciousness, epilepsy, gait or limb ataxia or movement disorders, among others. Treatment includes antiepileptics such as lamotrigine, valproate or topiramate, calcium blockers such as flunarizine or verapamil and acetazolamide.

Current and Novel Therapies for Cluster Headache: A Narrative Review.

Cluster headache (CH) is an excruciating and debilitating primary headache disorder. The prevalence is up to 1.3%, and the typical onset is around age 30. Often misdiagnosed as migraine, particularly in children, the diagnosis rate of CH has been increasing among women. CH is characterized by intense unilateral pain and autonomic symptoms, significantly impacting patients' quality of life, mental health, and productivity.Genetic associations suggest a familial risk for developing CH, with lifestyle factors also potentially playing a role. The pathophysiology involves alterations in both central and peripheral nervous system, with the hypothalamus, trigeminocervical complex, and neuropeptides such as calcitonin gene-related peptide (CGRP) being implicated.Nonpharmacological treatments focus on patient education and lifestyle modifications, while pharmacological treatments include acute therapies such as oxygen and subcutaneous or nasal sumatriptan, as well as preventive therapies like verapamil, lithium, and CGRP monoclonal antibodies. Transitional options include oral corticosteroids and greater occipital nerve injections. Emerging interventional procedures offer new avenues for managing refractory cases. Noninvasive vagal nerve stimulation and occipital nerve stimulation show promise for both acute and preventive treatment. Careful consideration of safety profiles is crucial in specific populations such as pregnant patients and children.Current treatments still leave patients highly burdened by limited efficacy and side effects. Future research continues to explore novel pharmacological targets, interventional procedures, and the potential role of psychedelics in CH management. Comprehensive, multifaceted treatment strategies are essential to improve the daily functioning and quality of life for individuals with CH.

Non-invasive neuromodulation of the cervical vagus nerve in rare primary headaches.

Primary headache disorders can be remarkably disabling and the therapeutic options available are usually limited to medication with a high rate of adverse events. Here, we discuss the mechanism of action of non-invasive vagal nerve stimulation, as well as the findings of the main studies involving patients with primary headaches other than migraine or cluster headache, such as hemicrania continua, paroxysmal hemicrania, cough headache, or short-lasting neuralgiform headache attacks (SUNCT/SUNA), in a narrative analysis. A bibliographical search of low-prevalence disorders such as rare primary headaches retrieves a moderate number of studies, usually underpowered. Headache intensity, severity, and duration showed a clinically significant reduction in the majority, especially those involving indomethacin-responsive headaches. The lack of response of some patients with a similar diagnosis could be due to a different stimulation pattern, technique, or total dose. The use of non-invasive vagal nerve stimulation for the treatment of primary headache disorders represents an excellent option for patients with these debilitating and otherwise refractory conditions, or that cannot tolerate several lines of preventive medication, and should always be considered before contemplating invasive, non-reversible stimulation techniques.

Pathophysiology and Therapy of Associated Features of Migraine.

Migraine is a complex and debilitating disorder that is broadly recognised by its characteristic headache. However, given the wide array of clinical presentations in migraineurs, the headache might not represent the main troublesome symptom and it can even go unnoticed. Understanding migraines exclusively as a pain process is simplistic and certainly hinders management. We describe the mechanisms behind some of the most disabling associated symptoms of migraine, including the relationship between the central and peripheral processes that take part in nausea, osmophobia, phonophobia, vertigo and allodynia. The rationale for the efficacy of the current therapeutic arsenal is also depicted in this article. The associated symptoms to migraine, apart from the painful component, are frequent, under-recognised and can be more deleterious than the headache itself. The clinical anamnesis of a headache patient should enquire about the associated symptoms, and treatment should be considered and individualised. Acknowledging the associated symptoms as a fundamental part of migraine has permitted a deeper and more coherent comprehension of the pathophysiology of migraine.

Case Report: Transformation of Visual Snow Syndrome From Episodic to Chronic Associated With Acute Cerebellar Infarct.

Visual snow syndrome is a novel neurological condition characterized by a panfield visual disturbance associated with several additional symptoms. Although it is usually a continuous and primary disorder, cases of intermittent visual snow have been described in the literature, as well as rare secondary forms. This report is the first description of a case of intermittent visual snow syndrome, which transformed into a persistent form following a posterior circulation stroke due to vertebral artery dissection. At 1 and 2 years after experiencing the acute cerebellar infarct, the patient's only neurological sequalae was visual snow. This case provides a description of how visual snow syndrome may be caused by an underlying brain disorder, and highlights the importance of the cerebellum in the pathophysiology of this relatively unknown condition. It further shows evidence of how existing predispositions might be relevant to the development of visual snow, in certain subjects and following specific circumstances.

New Generation Gepants: Migraine Acute and Preventive Medications.

Migraine is a debilitating disease whose clinical and social impact is out of debate. Tolerability issues, interactions, contraindications, and inefficacy of the available medications make new options necessary. The calcitonin-gene-related peptide (CGRP) pathway has shown its importance in migraine pathophysiology and specific medications targeting this have become available. The first-generation CGRP receptor antagonists or gepants, have undergone clinical trials but their development was stopped because of hepatotoxicity. The new generation of gepants, however, are efficacious, safe, and well tolerated as per recent clinical trials. This led to the FDA-approval of rimegepant, ubrogepant, and atogepant. The clinical trials of the available gepants and some of the newer CGRP-antagonists are reviewed in this article.

Emerging Targets for Migraine Treatment.

BACKGROUND: While understanding the pathophysiology of migraine has led to CGRP-based treatments, other potential targets have also been implicated in migraine. OBJECTIVES: To catalog new promising targets for the treatment of migraine. METHODS: We completed a literature review focusing on 5HT1F, PACAP, melatonin, and orexins. RESULTS: The 5HT1F receptor agonist lasmiditan, following two positive randomized placebo-controlled trials, was FDA-approved for the acute treatment of migraine. PACAP-38 has shown analogous evidence to what was obtained for CGRP with its localization in key structures, provocation tests, and positive studies when antagonizing its receptor in animal models, although a PAC-1 receptor monoclonal antibody study was negative. Melatonin has undergone several randomized controlled trials showing a positive trend. Filorexant is the only dual orexin receptor antagonist, which was tested in humans with negative results. CONCLUSIONS: Further and ongoing studies will determine the utility of these new therapies with lasmiditan and melatonin having demonstrated efficacy for the treatment of migraine.

Eptinezumab for the preventive treatment of migraine.

Our knowledge of the pathophysiology of migraine and the molecules implicated in the disorder have evolved over time. Among these, calcitonin gene-related peptide has shown a crucial role that led to the development of therapies specifically targeting the molecule. Four monoclonal antibodies targeting the calcitonin gene-related peptide pathway are currently available after the US FDA approval of eptinezumab for the indication of migraine prevention. This is the only one of the class to be administered intravenously. The pharmacology of eptinezumab and the four studies that led to the approval, two Phase II and two Phase III clinical trials, are reviewed in this paper. Eptinezumab has demonstrated efficacy, tolerability and safety in patients with episodic and chronic migraine. Studies including migraineurs who have failed previous preventives, and comparison with other options administered quarterly, as well as real-world experience data will all be welcome.