Indomethacin-responsive trigeminal autonomic cephalgias: a review of key characteristics and pathophysiology.

Trigeminal autonomic cephalgias (TACs) are a well-defined subset of uncommon primary headaches that share comparable onset, pathophysiology and symptom patterns. TACs are characterised by the presentation of one-sided and high-intensity trigeminal pain together with unilateral cranial autonomic signs, which can include lacrimation, rhinorrhea, and miosis. The International Classification of Headache Disorders 3rd Edition recognises four different headache entities in this group, with cluster headache as the most recognised among them. Hemicrania continua (HC) and paroxysmal hemicrania (PH) are both distinctive cephalgias of which the diagnostic criteria include an absolute response to indomethacin. Consequently, for this reason they are often referred to as 'indomethacin-responsive' TACs. The main focus of this review was to discuss the state of knowledge regarding the pathophysiology and key characteristics of PH and HC. Given the limited understanding of these conditions, and their exceptionally uncommon prevalence, a correct diagnosis can pose a clinical challenge and the search for an effective treatment may be prolonged, which frequently has a serious impact upon patients' quality of life. The information provided in this review is meant to help physicians to differentiate indomethacin-sensitive cephalgias from other distinct headache disorders with a relatively similar clinical presentation, such as cluster headache, trigeminal neuralgia, and various migraine conditions.

Hemicrania continua in a family: A report of two cases.

OBJECTIVE: To report two cases of hemicrania continua (HC) in a mother and daughter. BACKGROUND: HC is a rare primary headache disorder belonging to the family of trigeminal autonomic cephalalgias (TACs). Unlike migraine, familial cases of TACs are rare, and we know relatively little of their inheritance pattern and genetic mechanisms. METHODS: We present a mother and daughter with HC. We compare the similarities and differences between this family and the first report of familial HC and discuss the implications for future studies. RESULTS: Both the mother and daughter presented with a constant, side-locked headache of moderate intensity, with episodic exacerbations of more severe pain that are associated with ipsilateral cranial autonomic activation. After negative workup, both patients were started on indomethacin and achieved absolute response at different doses, confirming HC. CONCLUSIONS: Our report further corroborates other reports of familial TACs that TACs are primary headaches possibly attributable to genetic factors, albeit detailed mechanisms remain elusive. Nevertheless, whether clinical presentation and treatment responses would be substantially different between sporadic and familial HCs remain unclear.

The unique role of the trigeminal autonomic reflex and its modulation in primary headache disorders.

PURPOSE OF REVIEW: The trigeminal autonomic reflex is a physiological reflex with an important protective function which also plays a role in pathophysiological conditions, such as primary headache. It is not understood whether the autonomic symptoms in trigeminal autonomic cephalalgias and migraine are the consequence of severe trigeminal discharge or indeed directly driven by central generators as part of the pathophysiology, underlying these syndromes. RECENT FINDINGS: Modulating this reflex, and particularly the parasympathetic reflex arc, has been shown to be effective in treating headache. Among these modulators, left noninvasive vagal nerve stimulation has been shown to bilaterally inhibit the parasympathetic output of the reflex. Furthermore, the peripheral activation of the reflex, resulting in parasympathetic discharge, is not sufficient to provoke headache attacks in cluster headache patients, suggesting a central modulation. SUMMARY: Here, we review the anatomy and physiology of the trigeminal autonomic reflex and its involvement in primary headache. Possible candidates who have a modulating effect, including neurostimulation and pharmacological approaches, are described.

LASH syndrome: New cases with a broadening clinical phenotype.

OBJECTIVE: To describe three new cases of the headache syndrome of long-lasting autonomic symptoms with hemicrania (LASH), and to establish a clinical phenotype utilizing all LASH cases noted in the medical literature. METHODS: A case series of patients was evaluated in an academic headache clinic over a two-year time period. LASH syndrome was defined by episodic headache attacks with associated cranial autonomic symptoms that start before headache onset, last the entire duration of the headache and continue on for a period of time after the headache ceases. RESULTS: Three patients were noted to have LASH syndrome in a two-year time period (2017-2018). One patient was diagnosed with primary LASH, while two others had probable secondary LASH from a secretory pituitary tumor. The primary LASH patient was female. She had on average one headache per week lasting 1-3 days in duration. She experienced migrainous associated symptoms along with their cranial autonomic symptoms. She also developed a fixed Horner's syndrome along with a typical headache attack, which was present for 6 months at the time of consultation. She had complete headache relief with indomethacin and her miosis and ptosis also resolved with treatment. Secondary LASH was diagnosed in two patients (one male, one female) both with prolactin secreting pituitary microadenomas. One of the patients had his headaches abolish with dopamine agonist therapy while the other patient did not respond to hormonal modulation but became pain free on indomethacin. Secondary LASH patients had less frequent headache episodes and lacked any migrainous associated features, but exhibited agitation with headache. CONCLUSION: LASH syndrome may be rare, but more reported cases are entering the headache literature. The temporal profile of onset and offset of cranial autonomic symptoms is key to making the diagnosis. Primary and secondary LASH may present differently based on gender predominance, the presence of migrainous associated features, and attack frequency. Secondary LASH appears to be indomethacin responsive, suggesting that medication effectiveness should not obviate the need to do testing for secondary etiologies.

Do paroxysmal hemicrania and hemicrania continua represent different headaches? A retrospective study.

OBJECTIVE: Hemicrania continua and paroxysmal hemicrania are considered different headaches belonging to a group of trigeminal autonomic cephalalgias. However, they share many clinical features. Both headaches also show complete response to indomethacin, which is a mandatory criterion for their diagnosis. Are they really different headaches? To answer this question, we compared the pain characteristics and autonomic features between two headaches. We also determined whether paroxysmal hemicrania transforms into hemicrania continua or vice versa in their natural history. METHODS: The patients with hemicrania continua and paroxysmal hemicrania were compared for severity, location, character, and mean effective indomethacin dose. The number of autonomic features and their severity was also compared. The natural history of headache was looked into to see the evolution of hemicrania continua and paroxysmal hemicrania from episodic and chronic pains, respectively. RESULTS: We included 35 patients with hemicrania continua and 27 patients with paroxysmal hemicrania from July 2015 to March 2017. The mean age of patients with paroxysmal hemicrania was 34.42 years, and hemicrania continua was 37 years. Both groups were similar for majority of pain characteristics and number/severity of autonomic features. However, paroxysmal hemicrania had higher pain severity. Five patients transformed from paroxysmal hemicrania to hemicrania continua, and 3 patients transformed from hemicrania continua to paroxysmal hemicrania. CONCLUSION: Paroxysmal hemicrania and hemicrania continua were similar on majority of pain characteristics and autonomic features. The paroxysmal hemicrania and hemicrania continua are not exclusive headaches and can transform into each other.

The pathophysiology of the trigeminal autonomic cephalalgias, with clinical implications.

The hallmark of primary headaches belonging to the group known as the trigeminal autonomic cephalalgias is unilateral headache accompanied by cranial autonomic symptoms. Being relatively rare and poorly understood, they represent a clinical challenge, leading to underdiagnosis and undertreatment. While the headache is the most obvious and disabling symptom, it is only part of a complex symptomatology which hints at the involved pathophysiological mechanisms. Activation of the trigeminal-autonomic reflex results in the aforementioned cranial autonomic symptoms, which are well understood; however, it is obvious that this brainstem reflex is regulated by higher centers that seemingly play a pivotal role in the attacks and the wide range of other symptoms indicating a homeostatic disturbance. These symptoms, as well as a number of well-validated findings, implicate the hypothalamus in the pathophysiology. over the course of the past 2-3 decades, novel therapies and technological advances have helped increase our knowledge of these clinical syndromes, and will likely continue to do so in the coming years as we witness the arrival of new drugs and neurostimulation options. In this review, the clinical presentation for cluster headache, paroxysmal hemicrania, short-lasting unilateral neuralgiform headache with conjunctival injection and tearing, and hemicrania continua is covered, along with our current understanding of the common pathophysiology and clinical manifestations.

SUN: Short-Lasting Unilateral Neuralgiform Headache Attacks.

PREMISE: Short-lasting unilateral neuralgiform headache attacks (SUN) are part of the group of primary headaches called trigeminal autonomic cephalalgias (TACs). They are characterized by unilateral attacks of pain with associated ipsilateral cranial autonomic symptoms. PROBLEM: Recently the classification of these attacks has changed, to incorporate the different types of autonomic symptoms such as conjunctival injection and tearing (or lack thereof). Previously considered to be rare and rather refractory to treatment, there is an increasing awareness of this syndrome and the therapeutic possibilities. DISCUSSION: This article discusses the clinical aspects of the syndrome, pathophysiology, current, and future treatments.

Tics in TACs: A Step into an Avalanche? Systematic Literature Review and Conclusions.

BACKGROUND: Trigeminal autonomic cephalalgias (TACs) comprise cluster headache, paroxysmal hemicrania, short-lasting unilateral neuralgiform headache attacks, and hemicrania continua. In some cases, trigeminal neuralgia (TN, "tic douloureux") or TN-like pain may co-occur with TACs. AIM: This article will review the co-occurrence and overlap of TACs and tics in order to contribute to a better understanding of the issue and an improved management of the patients. METHODS: For performing a systematic literature review Pubmed was searched using a total of ten terms. The articles identified were screened for further articles of relevance. SUMMARY: TACs are related to tics in various ways. TN or TN-like paroxysms may co-occur with CH, PH, and HC, labeled as cluster-tic syndrome, PH-tic syndrome, and HC-tic syndrome. Such co-occurrence was not only found in the primary TACs but also in secondary headaches resembling TACs. The initial onset of TAC and tic may be simultaneous or separated by months or years. In acute attacks, tic and TAC may occur concurrently or much more often independently of each other. The term "cluster-tic syndrome" was also used in patients with a single type of pain in a twilight zone between TACs and TN fulfilling none of the relevant diagnostic criteria. Short-lasting neuralgiform headache attacks overlap with TN in terms of clinical features, imaging findings, and therapy.

LASH: A Review of the Current Literature.

PURPOSE OF REVIEW: The purpose of this review is to evaluate and explain our current understanding of a very rare disorder, long-lasting autonomic symptoms with associated hemicranias (LASH). RECENT FINDINGS: At present, there are four known cases in the literature of LASH. Its characteristics and reported response to indomethacin link it most closely to the trigeminal autonomic cephalalgias (TACs). Its pathophysiology and epidemiology remain unclear. Variance in the pain and autonomic symptom relationship in the existing TAC literature along with the reports of TAC sine headache suggests that LASH may represent a far end of the spectrum of TACs, with most similarities to paroxysmal hemicrania (PH) and hemicrania continua (HC).

Trigeminal autonomic cephalalgias.

The trigeminal autonomic cephalalgias (TACs) are a group of primary headache disorders characterised by lateralized symptoms: prominent headache and ipsilateral cranial autonomic features, such as conjunctival injection, lacrimation and rhinorrhea. The TACs are: cluster headache (CH), paroxysmal hemicrania (PH), short-lasting unilateral neuralgiform headache attacks with conjunctival injection and tearing (SUNCT)/short-lasting neuralgiform headache attacks with cranial autonomic features (SUNA) and hemicrania continua (HC). Their diagnostic criteria are outlined in the International Classification of Headache Disorders, third edition-beta (ICHD-IIIb). These conditions are distinguished by their attack duration and frequency, as well as response to treatment. HC is continuous and by definition responsive to indomethacin. The main differential when considering this headache is chronic migraine. Other TACs are remarkable for their short duration and must be distinguished from other short-lasting painful conditions, such as trigeminal neuralgia and primary stabbing headache. Cluster headache is characterised by exquisitely painful attacks that occur in discrete episodes lasting 15-180 min a few times a day. In comparison, PH occurs more frequently and is of shorter duration, and like HC is responsive to indomethacin. SUNCT/SUNA is the shortest duration and highest frequency TAC; attacks can occur over a hundred times every day.

Pain Part 9: Trigeminal Autonomic Cephalalgias.

The trigeminal autonomic cephalalgias are a group of rare, highly disabling, primary headache syndromes distinctly characterized by the unilaterality of their attacks and presence of cranial autonomic symptoms. Although pain is often localized to the peri-orbital and temporal regions, it is not uncommon for pain to radiate to tooth-bearing areas and mimic toothache or jaw pain. Hence, dental practitioners should be aware of these syndromes to enable appropriate referral and avoid unnecessary, and often irreversible, dental treatments. Many dentists will not have heard of these conditions but must remain vigilant, and ensure that they are not confused with trigeminal neuralgia, so that their patients are appropriately advised and referred. Clinical relevance: The dental practitioners may be the first line of healthcare providers consulted by these patients in the hope of obtaining pain relief. Lack of familiarity with an uncommon condition may lead to poor patient management.

Do trigeminal autonomic cephalalgias represent primary diagnoses or points on a continuum?

The question of whether the trigeminal autonomic cephalalgias (TACs) represent primary diagnoses or points on a continuum has been debatable for a number of years. Patients with TACs may present with similar clinical characteristics, and occasionally, TACS respond to similar treatments. Prima facie, these disorders may seem to be intimately related. However, due to the current evidence, it would be challenging to accurately conclude whether they represent different primary headache diagnoses or the same primary headache disorder represented by different points on the same continuum. Ultimately, the TACs may utilize similar pathways and activate nociceptive responses that result in similar clinical phenotypes but "original and initiating" etiology may differ, and these disorders may not be points on the same continuum. This paper seeks to provide a brief comparison of TACs via diagnostic criteria, secondary causes, brief overview of pathophysiology, and the use of some key treatments and their mechanism of actions to illustrate the TAC similarities and differences.

Tic versus TAC: differentiating the neuralgias (trigeminal neuralgia) from the cephalalgias (SUNCT and SUNA).

Trigeminal neuralgia, short-lasting unilateral neuralgiform headache attacks with conjunctival injection and tearing (SUNCT) and short-lasting unilateral neuralgiform headache attacks with autonomic symptoms (SUNA) are classified as distinct disorders in the International Classification of Headache Disorders 3 beta (ICHD-3 beta). SUNCT and SUNA are primary headache disorders included among the trigeminal autonomic cephalalgias. Trigeminal neuralgia is classified under painful cranial neuropathies and other facial pains. The classification criteria of these conditions overlap significantly which could lead to misdiagnosis. The reported overlap among these conditions has called into question whether they should be considered distinct entities or rather a continuum of the same disorder. This review explores the known overlap and how other features not included in the ICHD-3 beta criteria may better differentiate the "Tics" (trigeminal neuralgia) from the "TACs" (SUNCT and SUNA).

Hemicrania continua with contralateral cranial autonomic features: a case report.

BACKGROUND: Hemicrania continua is characterized by continuous strictly unilateral head pain with episodic exacerbations. Episodic exacerbations are associated with ipsilateral cranial autonomic features. CASE DESCRIPTION: We report a 24-year female with a 2-year history of continuous right-sided headache with superimposed exacerbations. Episodic exacerbations were associated with marked agitation and contralateral cranial autonomic features. The patient showed a complete response to indomethacin within 8 hours. DISCUSSION: The dichotomy of pain and autonomic features is in accordance with the concept about the possibility of two separate pathways for pain and autonomic features in trigeminal autonomic cephalalgias.

SUNCT, SUNA and trigeminal neuralgia: different disorders or variants of the same disorder?

PURPOSE OF REVIEW: Short-lasting unilateral neuralgiform headache attacks with conjunctival injection and tearing (SUNCT), short-lasting unilateral neuralgiform headache attacks with autonomic symptoms (SUNA) and trigeminal neuralgia are considered different disorders, thus grouped in separate sections of the International Classification of Headache Disorders 3 beta. However, the clinical, radiological and therapeutic overlap between SUNCT, SUNA, and trigeminal neuralgia has challenged this traditional view. This review summarizes the available clinical and pathophysiological evidence on whether SUNCT, SUNA and trigeminal neuralgia should be considered separate entities or variants of the same disorder. RECENT FINDINGS: Data on the clinical phenotype and effective management strategies in SUNCT and SUNA syndromes have shown striking similarities with trigeminal neuralgia. Moreover, studies exploring radiological findings supported the hypothesis of common aetiological and pathophysiological basis between SUNCT/SUNA and trigeminal neuralgia. However, a limitation of most studies is that they have included small samples of patients and therefore any conclusions need to be drawn cautiously. SUMMARY: Despite being considered distinct conditions, emerging clinical and radiological evidence supports a broader nosological concept of SUNCT, SUNA, and trigeminal neuralgia. These conditions may constitute a continuum of the same disorder, rather than separate clinical entities. Further evidence is required to shed light on this nosological issue, given its potential impact on clinical practice and further research studies in this area.

Sleep in trigeminal autonomic cephalagias: a review.

PURPOSE OF REVIEW: Sleep and cluster headache (CH) are believed to be interconnected but the precise relation to the other trigeminal autonomic cephalalgias (TACs) is uncertain and complex. A better understanding of these relations may eventually lead to a clarification of the underlying mechanisms and eventually to more effective therapeutic regimens. This review aims to evaluate the existing literature on the subject of TACs and sleep. An association between episodic CH and distinct macrostructural sleep phases, especially the relation to rapid eye movement (REM) sleep, has been described in some older studies but could not be confirmed in other, more recent studies. Investigations into the microstructure of sleep in these patients are lacking. Only a few case reports exist on the relation between sleep and other TACs. SUMMARY: Recent studies do not find an association between CH and REM sleep. One older study suggests chronic paroxysmal hemicranias may be locked to REM sleep but otherwise the relation is unknown. Reports indicate that CH and obstructive sleep apnoea are associated in some individuals but results are diverging. Single cases show improvement of CH upon treatment of sleep apnoea, but the causal relationship remains in question. Other TACs are probably not connected to sleep and strictly nocturnal attacks should prompt investigations for secondary causes. The relation between CH and sleep is, however, fascinating and detailed sleep studies in carefully diagnosed patients are warranted.

Strictly unilateral headaches: considerations of a clinician.

The aim of the lecture is to draw attention to the role that clinical practice and clinical observation have had in stimulating research on the pathophysiology of cluster headache (CH) and other trigeminal autonomic cephalalgias (TACs). The symptoms of cluster headache-in particular the typical circadian periodicity of the headaches and the seasonal recurrence of cluster periods-were fundamental in shifting attention away from peripheral pathogenetic hypotheses to the idea that cluster headache could have a central origin. Initially, solid neuroendocrinological data pointed to hypothalamic involvement. For example, CH patients were shown to have alterations in biorhythms. Subsequently, modern functional neuroimaging techniques were able to demonstrate that the homolateral posterior hypothalamus is activated during TAC headaches, so implicating this region in TAC pathogenesis. It is known that the hypothalamus has a modulatory effect on nociceptive and autonomic pathways, particularly on the nociceptive trigeminovascular system. Future research should clarify whether the hypothalamus is the generator of TAC headaches, or whether it is activated in response to an alteration of the homeostatic equilibrium between limbic emotional-affective components and autonomic-nociceptive components modulated by the hypothalamus.

Trigeminal autonomic cephalalgias: beyond the conventional treatments.

The trigeminal autonomic cephalalgias include cluster headache, paroxysmal hemicrania, short-lasting unilateral neuralgiform headache attacks, and hemicrania continua. While the majority responds to conventional pharmacological treatments, a small but significant proportion of patients are intractable to these treatments. In these cases, alternative choices for these patients include oral and injectable drugs, lesional or resectional surgery, and neurostimulation. The evidence base for conventional treatments is limited, and the evidence for those used beyond convention is more so. At present, the most evidence exists for nerve blocks, deep brain stimulation, occipital nerve stimulation, sphenopalatine ganglion stimulation in chronic cluster headache, and microvascular decompression of the trigeminal nerve in short-lasting unilateral neuralgiform headache attacks.