Melatonin in hemicrania continua and paroxysmal hemicrania.

BACKGROUND: Hemicrania continua (HC) and paroxysmal hemicrania (PH) belong to a group of primary headache disorders called trigeminal autonomic cephalalgias. One of the diagnostic criteria for both HC and PH is the absolute response to the therapeutic dose of indomethacin. However, indomethacin is discontinued in many patients as a result of intolerance to its side effects. Melatonin, a pineal hormone, which shares similar chemical structure to indomethacin, has been reported to have some efficacy for HC in previous case reports and series. To our knowledge, there is no literature regarding the use of melatonin in PH. We aimed to describe the clinical use of melatonin in the preventive management of HC and PH. METHODS: Patient level data were extracted as an audit from routinely collected clinical records in consecutive patients seen in outpatient neurology clinic at King's College Hospital, London, UK, from September 2014 to April 2023. Our cohort of patients were identified through a search using the keywords: hemicrania continua, paroxysmal hemicrania, melatonin and indomethacin. Descriptive statistics including absolute and relative frequencies, mean ± SD, median and interquartile range (IQR) were used. RESULTS: Fifty-six HC patients were included with a mean ± SD age of 52 ± 16 years; 43 of 56 (77%) patients were female. Melatonin was taken by 23 (41%) patients. Of these 23 patients, 19 (83%) stopped indomethacin because of different side effects. The doses of melatonin used ranged from 0.5 mg to 21 mg, with a median dose of 10 mg (IQR = 6-13 mg). Fourteen (61%) patients reported positive relief for headache, whereas the remaining nine (39%) patients reported no headache preventive effect. None of the patients reported that they were completely pain free. Two patients continued indomethacin and melatonin concurrently for better symptom relief. Eight patients continued melatonin as the single preventive treatment. Side effects from melatonin were rare. Twenty-two PH patients were included with mean ± SD age of 50 ± 17 years; 17 of 22 (77%) patients were female. Melatonin was given to six (27%) patients. The median dose of melatonin used was 8 mg (IQR = 6-10 mg). Three (50%) patients responded to melatonin treatment. One of them used melatonin as adjunctive treatment with indomethacin. CONCLUSIONS: Melatonin showed some efficacy in the treatment of HC and PH with a well-tolerated side effect profile. It does not have the same absolute responsiveness as indomethacin, at the doses used, although it does offer a well-tolerated option that can have significant ameliorating effects in a substantial cohort of patients.

Epidemiology and clinical features of paroxysmal hemicrania: A systematic review and meta-analysis.

OBJECTIVE: To assess the prevalence or relative frequency of paroxysmal hemicrania and its clinical features in the adult general population and among adult patients evaluated for headache in tertiary care. BACKGROUND: Paroxysmal hemicrania is a rare trigeminal autonomic cephalalgia with characteristic attacks of headache, associated cranial autonomic symptoms and signs, and an absolute response to indomethacin. Its epidemiological burden remains unknown in both the adult general population and among adult patients evaluated for headache in a tertiary care setting. Moreover, the frequencies of the clinical features associated with paroxysmal hemicrania have not been well established. METHODS: A literature search of PubMed and Embase was conducted from January 1, 1988, to January 20, 2023. Eligible for inclusion were observational studies reporting the point prevalence or relative frequency of paroxysmal hemicrania or its clinical features in the adult general population or among adult patients evaluated for headache in tertiary care. Two independent investigators (M.J.H. and J.G.L.) performed the title, abstract, and full-text article screening. Each included study's risk of bias was critically appraised using the Joanna Briggs Institute Critical Appraisal Checklist for Studies Reporting Prevalence Data. Estimates of prevalence or relative frequency were calculated using a random-effects meta-analysis. The between-study heterogeneity was assessed using the I2 statistic and further explored with meta-regression. This study was pre-registered on PROSPERO (identifier: CRD42023391127). RESULTS: A total of 17 clinic-based studies and one population-based study met the eligibility criteria. Importantly, an overall high risk of bias was observed across the eligible studies. The relative frequency of paroxysmal hemicrania was estimated to be 0.3% (95% CI, 0.2%-0.5%) among adult patients evaluated for headache in tertiary care with considerable heterogeneity (I2 = 76.4%). No cases with paroxysmal hemicrania were identified among 1,838 participants in a population-based sample. Moreover, the most prevalent cranial autonomic symptoms were lacrimation (77.3% [95% Cl, 62.7%-87.3%]), conjunctival injection (75.0% [95% Cl, 60.3%-85.6%]), and nasal congestion (47.7% [95% Cl, 33.6%-62.3%]). CONCLUSIONS: Our findings suggest that paroxysmal hemicrania is a rare disorder among adults evaluated for headache in tertiary care, while its prevalence in the general population remains unknown. Further studies focusing on the clinical features of paroxysmal hemicrania are warranted.

Neurophysiological investigations in a case of primary paroxysmal hemicrania-tic syndrome.

BACKGROUND: The association between paroxysmal hemicrania (PH) and trigeminal neuralgia-the so-called PH-tic syndrome-has rarely been described. However, a correct diagnosis is crucial since both disorders require specific treatments. Little is known about pathophysiological mechanisms, and, to date, there are no electrophysiological studies in patients with PH-tic syndrome. CASE: We describe the case of a 52-year-old man with a PH-tic syndrome successfully treated with an association of carbamazepine (1200 mg/day) and indomethacin (150 mg/die). Patient underwent trigeminal reflex testing, including blink and masseter inhibitory reflex, and laser-evoked potential (LEP) recording after supraorbital region stimulation in the affected and unaffected side. Both neurophysiological investigations resulted normal; LEPs failed to detect any latency asymmetry between both sides. CONCLUSIONS: Neurophysiological findings demonstrate for the first time the integrity of somatosensory system in a primary PH-tic syndrome case. Central pathophysiological mechanisms and hypothalamic dysregulation may contribute to the development of this rare syndrome.

One-year prevalence of cluster headache, hemicrania continua, paroxysmal hemicrania and SUNCT in Norway: a population-based nationwide registry study.

BACKGROUND: There is lack of population-based studies evaluating the prevalence of paroxysmal hemicrania, hemicrania continua and short-lasting unilateral neuralgiform headache attacks. OBJECTIVES: The aim of this study was to investigate the gender-specific 1-year prevalence of cluster headache, paroxysmal hemicrania, hemicrania continua, and short-lasting unilateral neuralgiform headache attacks. METHODS: A nationwide study was conducted from January 1 2022 and December 31 2022 by linking diagnostic codes from Norwegian Patient Registry and prescription of relevant drugs from Norwegian Prescription Database on an individual basis. The 1-year prevalence with 95% confidence intervals (CI) of cluster headache, paroxysmal hemicrania, hemicrania continua and short-lasting unilateral neuralgiform headache attacks are estimated based on the combination of diagnostic codes, prescription of drugs and corresponding reimbursement codes. RESULTS: Among 4,316,747 individuals aged ≥ 18 years, the 1-year prevalence per 100,000 was 14.6 (95% CI 13.5-15.8) for cluster headache, 2.2 (95% CI 1.8-2.7) for hemicrania continua, 1.4 (95% CI 1.0-1.8) for paroxysmal hemicrania, and 1.2 (95% CI 0.8-1.4) for short-lasting unilateral neuralgiform headache attacks. For all the trigeminal autonomic cephalalgies, cluster headache included, the prevalence was higher for women than men. CONCLUSIONS: In this nationwide register-based study, we found a 1-year prevalence per 100,100 of 14.6 for cluster headache, 2.2 for hemicranias continua, 1.4 for paroxysmal hemicranias, and 1.2 for short-lasting unilateral neuralgiform headache attacks. This is the first study reporting higher prevalence of cluster headache for women than men.

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.

Paroxysmal hemicrania and hemicrania continua: Review on pathophysiology, clinical features and treatment.

BACKGROUND: Paroxysmal hemicrania and hemicrania continua are indometacin-sensitive trigeminal autonomic cephalalgias, a terminology which reflects the predominant distribution of the pain, observable cranial autonomic features and shared pathophysiology. Understanding the latter is limited, both by low prevalence and the intricacies of studying brain function, requiring multimodal techniques to glean insights into such disorders. Similarly obscure is the curious response to indometacin. This review will address what is currently known about pathophysiology, the rationale for the current classification and, features which may confound the diagnosis, such as lack of cranial autonomic symptoms and those which are typically associated with migraine such as nausea, photophobia, phonophobia and aura. Despite these characteristics, a dramatic response to indometacin, which is not seen in migraine nor the other trigeminal autonomic cephalalgias , provides the hallmark of the diagnosis. The main clinical differential for paroxysmal hemicrania is based on temporal pattern and lies between cluster headache and short-lasting-neuralgiform headache attacks with tearing or additional cranial autonomic symptoms. For hemicrania continua it is more challenging as the main differential for which the disorder is often treated is migraine. A prior episodic pattern, often days at a time, and the tendency to exacerbation with analgesics will further deflect from the diagnosis. The relevance of this is that there is little overlap in therapeutics between paroxysmal hemicrania and hemicrania continua and other headache disorders and there are limited effective alternatives to indometacin. The most effective are other non-steroidal anti-inflammatory drugs including the newer COX-II inhibitors. Even though early reports suggest that a higher indometacin dose-requirement may herald a secondary precipitating pathology, this does not seem to be the case, with syndrome and response to treatment being similar with the primary disorder. In this context imaging of new onset paroxysmal hemicrania or hemicrania continua and implication of the results will be discussed as will alternative treatment options.

Paroxysmal hemicrania in children and adolescents: A systematic review.

OBJECTIVE: We aimed to report the accessible demographic, clinical, and radiological characteristics of reported pediatric paroxysmal hemicrania (PH). INTRODUCTION: It has been a while since PH in a child was first described. However, it is still unknown whether children's PH follows the same patterns as adults. METHODS: This study followed the latest version of PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses). PubMed, Web of Science, and Scopus were searched systematically without time limitation. We included all English-language, peer-reviewed articles, including observational or interventional studies reporting PH cases in children or adolescents based on the International Classification of Headache Disorders (ICHD) criteria. Data extracted included PH class; sex; age; age of onset; frequency, duration, site, severity, and quality of pains; triggers; and autonomic and migrainous symptoms, as well as a sense of restlessness/agitation, response to treatment, laboratory investigations, imaging, comorbidity, and family history. For quality assessment, two independent reviewers (MB and VM) assessed the methodological quality of the included studies through the Joanna Briggs Institute's critical appraisal checklist. RESULTS: A total of 182 records were identified and reduced to 116 after removing duplicates. After screening, 22 articles met the inclusion criteria. Overall, the studies represented 35 children or adolescents with PH. We found a boy-to-girl ratio of 1.125:1. Onset occurred at a broad range of 1 to 14 years old. The mean age of onset among reported cases in children and adolescents was 6.5 years, while the mean age of diagnosis was 8.2 years. [Correction added on 22 August 2022, after first online publication: In the preceding sentence, 6.3 and 7.9 years were changed to 6.5 and 8.2 years, respectively.] The attacks' frequency and duration were greatly varied. Left-sided pain occurred twice as often as right-sided pain. The characteristics of the pain were usually severe in intensity. In nearly all of the cases, it was accompanied by ipsilateral cranial autonomic features. While most attacks were spontaneous, there were some common triggers. The physical examination, electroencephalogram, and brain magnetic resonance imaging had normal findings. Almost all patients benefited from indomethacin and showed complete responses to treatment, while some needed combination treatment of indomethacin with other medications. CONCLUSION: Although pediatric-onset PH has similar features to adult-onset PH, there are some challenges with ICHD criteria for younger children that limit the ability to confidently assign a diagnosis. Moreover, owing to concomitant migrainous features, PH may be confused with migraine in children and adolescents.

Paroxysmal hemicrania masquerading as a stroke in an elderly gentleman: case report.

BACKGROUND: Paroxysmal hemicrania has not been associated with ipsilateral weakness, loss of sensation and Horner's syndrome. This report is the first of its kind documented in literature. CASE PRESENTATION: This was an elderly, sixty-five-year-old Chinese male who presented with a headache fulfilling criteria of paroxysmal hemicrania and was found to have signs of ipsilateral conjunctival injection, Horner's syndrome, weakness and loss of sensation; with resolution of the patient's physical signs after relief of the headache. Brain magnetic resonance imaging did not show any strokes or other headache mimics. The patient had a marked response to indomethacin and a decrease of headache intensity and frequency with indomethacin prophylaxis. CONCLUSIONS: Paroxysmal hemicrania has joined the list of stroke chameleons and that it would be one of the differentials in a patient with hemiplegia, hemisensory loss, autonomic signs and severe headache. It suggests that paroxysmal hemicrania in the elderly present atypically.

Case Report: Shortest Course of Pediatric Paroxysmal Hemicrania.

Paroxysmal hemicrania (PH) is a rare primary headache disorder, especially among children. We describe herein a case with the shortest course of pediatric PH among previously reported cases, and the first case report of Japanese pediatric PH. An 11-year-old boy was referred to our clinic by his primary care physician for a headache evaluation. He had been complaining of severe, sharp, pulsating headache for 5 days. Attacks were restricted to the left side with a duration ranging from 2 to 20 minutes, 20-30 times a day. Attacks were associated with left autonomic symptoms (conjunctival injection, lacrimation, nasal congestion, eyelid edema, and ptosis). Two days after we prescribed indomethacin at 0.9 mg/kg/day, the patient was headache free. He stopped taking indomethacin 14 days after consultation because of drug eruptions. As of the time of writing, more than 1 year later, he has experienced no recurrence of headache. This case indicates the importance of improving awareness among general doctors regarding PH in children, and of conducting further investigations about low-dose, short-term indomethacin treatment.

Hemicrania Continua-Like Headache Related to Transdermal Nitroglycerine Therapy.

Several cases of symptomatic hemicrania continua (HC) have been reported. A 66-year-old man, suffering from migraine without aura, presented with a four month history of a new headache fulfilling the ICHD 3beta clinical criteria for HC. HC onset was strictly related to the use of transdermal nitroglycerine patch (TNP). In agreement with the cardiologist, TNP was discontinued and the headache promptly disappeared; symptoms reappeared within 6-12 hours after nitroglycerine reintroduction. After permanent discontinuation of TNP, headache disappeared at one year follow-up. To the best of our knowledge, this is the first report of the occurrence of an HC-like headache related to TNP.

"Cough Hemicrania" - An Overlapping Form of Headache: Case Reports.

OBJECTIVE: To describe two patients with recurring unilateral brief headaches that fulfilled criteria for both primary cough headache (CH) and chronic paroxysmal hemicrania (CPH). BACKGROUND: CH is typically a bilateral headache, specifically triggered by cough, straining, or other Valsalva maneuvers. The report of cases sharing features with other primary headache disorders, such as CPH, suggest common pathogenic mechanisms. METHODS: Case reports. RESULTS: Two patients (one man), aged 55 and 64, had a two-year history of daily, unilateral, side-locked headache attacks, lasting about 15 minutes, and associated with ipsilateral tearing. Headaches were triggered by cough, sneezing, laughing, or bending forward. Both patients experienced a marked and sustained improvement with indomethacin, and both relapsed when it was interrupted. CONCLUSIONS: These cases suggest the existence of transitional phenotypes, or shared pathogenic mechanisms, between CH and CPH, two indomethacin-responsive headaches. A more comprehensive analysis of different CH subtypes is necessary to understand their relation with other primary headaches.

Therapeutical approaches to paroxysmal hemicrania, hemicrania continua and short lasting unilateral neuralgiform headache attacks: a critical appraisal.

BACKGROUND: Hemicrania continua (HC), paroxysmal hemicrania (PH) and short lasting neuralgiform headache attacks (SUNCT and SUNA) are rare syndromes with a difficult therapeutic approach. The aim of this review is to summarize all articles dealing with treatments for HC, PH, SUNCT and SUNA, comparing them in terms of effectiveness and safety. METHODS: A survey was performed using the pubmed database for documents published from the 1st January 1989 onwards. All types of articles were considered, those ones dealing with symptomatic cases and non-English written ones were excluded. RESULTS: Indomethacin is the best treatment both for HC and PH. For the acute treatment of HC, piroxicam and celecoxib have shown good results, whilst for the prolonged treatment celecoxib, topiramate and gabapentin are good options besides indomethacin. For PH the best drug besides indomethacin is piroxicam, both for acute and prolonged treatment. For SUNCT and SUNA the most effective treatments are intravenous or subcutaneous lidocaine for the acute treatment of active phases and lamotrigine for the their prevention. Other effective therapeutic options are intravenous steroids for acute treatment and topiramate for prolonged treatment. Non-pharmacological techniques have shown good results in SUNCT and SUNA but, since they have been tried on a small number of patients, the reliability of their efficacy is poor and their safety profile mostly unknown. CONCLUSIONS: Besides a great number of treatments tried, HC, PH, SUNCT and SUNA management remains difficult, according with their unknown pathogenesis and their rarity, which strongly limits the studies upon these conditions. Further studies are needed to better define the treatment of choice for these conditions.

Hemicrania continua may respond to repetitive sphenopalatine ganglion block: A case report.

BACKGROUND: Hemicrania continua (HC) is a chronic headache disorder characterized by a continuous, strictly unilateral head pain accompanied by cranial autonomic symptoms, which completely responds to indomethacin; however, few alternative treatment options exist for the patients with this disorder who cannot tolerate indomethacin. Sphenopalatine ganglion (SPG) block has been used for the treatment of various headaches, with the strongest evidence for efficacy in cluster headache. CASE REPORT: A 52-year-old woman with a 7-year history of HC was evaluated in our clinic for management of her headaches after she had stopped using indomethacin due to a bleeding gastrointestinal ulcer. After failing multiple pharmacologic therapies, she was treated with repetitive SPG blocks using bupivacaine (0.6 mL at 0.5%) twice a week for 6 weeks and followed by maintenance therapy. This treatment protocol resulted in significant improvement in her headaches, mood, and functional capacity. CONCLUSION: SPG block using a local anesthetic may be an effective treatment for patients with HC, specifically for those who cannot tolerate indomethacin, or when this drug is contraindicated.

When indomethacin fails: additional treatment options for "indomethacin responsive headaches".

Indomethacin has been used for the treatment of headache disorders since the 1960's, shortly after it was introduced as a treatment for pain and joint swelling in rheumatologic conditions. A subgroup of primary headache disorders, often refractory to other pharmacologic treatment such as triptans and the usual non-steroidal anti-inflammatories, was noted to be exquisitely and absolutely responsive to the analgesic effects of indomethacin. These disorders have been better characterized over the past decade and classified into primary headache disorders of paroxysmal hemicrania (PH) and hemicrania continua (HC). Since the current ICHD-3 beta requires response to indomethacin as a diagnostic criterion, studies on alternative treatments in HC and PH generally occur in patients with intolerance to its gastro-intestinal side effects rather than loss of analgesia effectiveness. More rarely, the development of new headaches have been reported in chronic indomethacin use. In these settings, other classes of medications such as selective cyclooxygenase-2 inhibitors (celecoxib), anti-epileptic agents (topiramate), calcium channel blockers (verapamil, flunarizine), melatonin, and local nerve blocks with anesthetic and steroids have been shown to be effective in case reports and series. We review the literature and provide our clinical recommendations on alternative therapies for the "indomethacin-responsive headaches".

Diagnose and adios: practical tips for the ongoing evaluation and care of TAC patients taking indomethacin.

Paroxysmal hemicrania and hemicrania continua are primary headache disorders characterized by unilateral attacks of severe pain around the orbit with associated autonomic features. They are unique in their absolute response to indomethacin. Diagnosis is made when patients with suspected paroxysmal hemicrania or hemicrania continua have the resolution of headache with therapeutic doses of indomethacin. Once diagnosis is made, limited data exists on the ongoing management of these patients. For patients who do not tolerate indomethacin, or wish to come off medication, there remain few options. This article will discuss the diagnosis of paroxysmal hemicrania and hemicrania continua and the ongoing management of patients on indomethacin, as well as options for patients who do not tolerate or need to come off indomethacin.

Paroxysmal hemicrania: an update.

Paroxysmal hemicrania (PH) is an underreported and underdiagnosed primary headache disorder. It usually begins in the third or fourth decade of life. The recent observations indicate that it is equally prevalent in both males and females. PH is characterized by severe, strictly unilateral head pain attacks that occur in association with ipsilateral autonomic features. The attacks in PH are shorter and more frequent compared with cluster headache (CH) but otherwise PH and CH have similar clinical features. The hallmark of PH is the absolute cessation of the headache with indomethacin. However, a range of drugs may show partial to complete relief in certain groups of patients. Neuromodulatory procedures, such as greater occipital nerve blockade, blockade of sphenopalatine ganglion and neurostimulation of the posterior hypothalamus, are reserved for refractory PH.

Indomethacin-Responsive Headache Disorders.

OBJECTIVE: This article describes the clinical features and treatment of the indomethacin-responsive headache disorders paroxysmal hemicrania and hemicrania continua. LATEST DEVELOPMENTS: Both paroxysmal hemicrania and hemicrania continua are treated with indomethacin at the lowest clinically useful dose. It has recently become clear that some patients with either condition may respond to treatment with noninvasive vagus nerve stimulation, which can be both indomethacin sparing and, in some cases, headache controlling. Given the lifelong nature of both paroxysmal hemicrania and hemicrania continua, brain imaging with MRI is recommended when the conditions are identified, specifically including pituitary views. ESSENTIAL POINTS: Paroxysmal hemicrania and hemicrania continua are indomethacin-responsive headache disorders that offer a rewarding and unique opportunity to provide marked clinical improvement when recognized and treated appropriately. These disorders share the final common pathway of the trigeminal-autonomic reflex, with head pain and cranial autonomic features, and are differentiated pathophysiologically by the pattern of brain involvement, which can be seen using functional imaging. They have distinct differential diagnoses to which the clinician needs to remain alert.

Diagnosis and clinical features of trigemino-autonomic headaches.

Although severe short-lasting headaches are rare, they can be considered disabling conditions with a major impact on the quality of life of patients. These headaches can divided broadly in to those associated with autonomic symptoms, so called trigeminal autonomic cephalgias (TACs), and those with few or no autonomic symptoms. The TACs include cluster headache, paroxysmal hemicranias, hemicrania continua, and short-lasting unilateral neuralgiform headache attacks with cranial autonomic symptoms as well as short-lasting unilateral neuralgiform headache attacks with conjunctival injection and tearing syndrome. In all of these syndromes, half-sided head pain and ipsilateral cranial autonomic symptoms such as lacrimation or rhinorrhea are prominent. The paroxysmal hemicranias have, unlike cluster headaches, a very robust response to indomethacin, leading to a notion of indomethacin-sensitive headaches. The diagnosis of TACs is exclusively a clinical task. Because of the fact that cluster headache is strictly half-sided, typically involves the region around the eye and temple and often starts in the upper jaw, most patients first consult a dentist or ophthalmologist. No single instrumental examination has yet been able to define, or ensure, the correct diagnosis, or differentiate idiopathic headache syndromes. It is crucial that a trained neurologist sees these patients early so that management can be optimized and unnecessary procedures can be avoided. Although TACS are, in comparison to migraine, quite rare, they are nevertheless clinically very important for the neurologist to consider as they are easy to diagnose and the treatment is very effective in most patients.

Paroxysmal hemicrania: a retrospective study of a consecutive series of 22 patients and a critical analysis of the diagnostic criteria.

BACKGROUND: Paroxysmal hemicrania (PH) is a probably underreported primary headache disorder. It is characterized by repeated attacks of severe, strictly unilateral pain lasting 2 to 30 minutes localized to orbital, supraorbital, and temporal areas accompanied by ipsilateral autonomic features. The hallmark of PH is the absolute cessation of the headache with indomethacin. However, these all features may not be present in all cases and a few cases may remain unclassified according to the 2nd Edition of The International classification of Headache Disorders (ICHD-II) criteria for PH. METHODS: Twenty-two patients were included in this retrospective observation. RESULTS: We describe 17 patients, observed over six years, who fulfilled the ICHD-II criteria for PH. In parallel, we identified five more patients in whom one of the features of the diagnostic criteria for PH was missing. Two patients did not show any evidence of cranial autonomic feature during the attacks of headache. Another two patients did not fulfill the criteria for PH as the maximum attack frequency was less than five. One patient had an incomplete response to indomethacin. CONCLUSION: A subset of patients may not have all the defined features of PH and there is a need for refinement of the existing diagnostic criteria.