Treatment of Hemicrania Continua: Case Series and Literature Review

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.

Hemicrania continua: clinical review, diagnosis and management

Hemicrania continua (HC) is an indomethacin-responsive primary headache disorder which is currently classified under the heading of trigeminal autonomic cephalalgias (TACs). It is a highly misdiagnosed and underreported primary headache. The pooled mean delay of diagnosis of HC is 8.0 ± 7.2 years. It is not rare. We noted more than 1000 cases in the literature. It represents 1.7% of total headache patients attending headache or neurology clinic. Just like other TACs, it is characterized by strictly unilateral pain in the trigeminal distribution, cranial autonomic features in the same area and agitation during exacerbations/attacks. It is different from other TACs in one aspect. While all other TACs are episodic, HC patients have continuous headaches with superimposed severe exacerbations. The central feature of HC is continuous background headache. However, the patients may be worried only for superimposed exacerbations. Focusing only on exacerbations and ignoring continuous background headache are the most important factors for the misdiagnosis of HC. A large number of patients may have migrainous features during exacerbation phase. Up to 70% patients may fulfill the diagnostic criteria for migraine during exacerbations. Besides migraine, its exacerbations can mimic a large number of other primary and secondary headaches. The other specific feature of HC is a remarkable response to indomethacin. However, a large number of patients develop side effects because of the long-term use of indomethacin. A few other medications may also be effective in a subset of patients with HC. Various surgical interventions have been suggested for patients who are intolerant to indomethacin. Several aspects of HC are still not defined. There is a great heterogeneity in types of patients or articles on the HC in the literature. Diagnostic criteria have been modified several times over the years. The current diagnostic criteria are too restrictive in some aspects. We suggest a more accommodating type of criteria for the appendix of International Classification of Headache Disorder (ICHD).

Gabapentin in Headache Disorders: What Is the Evidence?

OBJECTIVE

Gabapentin (GBP), originally an antiepileptic drug, is more commonly used in the treatment of pain, including headache disorders. Off-label GBP is used in headache disorders with some success, some failure, and much debate. Due to this ambiguity, a clinical evidence literature review was performed investigating GBP's efficacy in headache disorders.

METHODS

Bibliographic reference searches for GBP use in headache disorders were performed in PUBMED and OVID Medline search engines from January 1, 1983 to August 31, 2014. Based on abstracts read by two reviewers, references were excluded if: GBP was not a study compound or headache symptoms were not studied. The resulting references were then read, reviewed, and analyzed.

RESULTS

Fifty-six articles pertinent to GBP use in headache disorders were retained. Eight headache clinical trials were quality of evidence Class 2 or higher based on American Academy of Neurology criteria. Seven of the eight clinical trials showed statistically significant clinical benefit from GBP in various headache syndromes (though modest affects at times). One study, Mathew et al., had concerns about intention-treat analysis breaches and primary outcomes.

CONCLUSION

Despite the conflicting evidence surrounding select studies, a significant amount of evidence shows that GBP has benefit for a majority of primary headache syndromes, including chronic daily headaches. GBP has some efficacy in migraine headache, but not sufficient evidence to suggest primary therapy. When primary headache treatments fail, a GBP trial may be considered in the individual patient.

Indomethacin-responsive headaches

Indomethacin-responsive headaches are a heterogeneous group of primary headache disorders distinguished by their swift and often absolute response to indomethacin. The epidemiology of these conditions is incompletely defined. Traditionally, indomethacin-responsive headaches include a subset of trigeminal autonomic cephalalgias (paroxysmal hemicrania and hemicrania continua), Valsalva-induced headaches (cough headache, exercise headache, and sex headache), primary stabbing headache, and hypnic headache. These headache syndromes differ in extent of response to indomethacin, clinical features, and differential diagnoses. Neuroimaging is recommended to investigate for various organic causes that may mimic these headaches. Case reports of other primary headache disorders that also respond to indomethacin, such as cluster headache, nummular headache, and ophthalmoplegic migraine, have been described. These "novel" indomethacin-responsive headaches beg the question of what headache characteristics are required to qualify a headache as an indomethacin-responsive headache. Furthermore, they challenge the concept of using a therapeutic intervention as a diagnostic criterion.

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.

Orofacial pain syndromes: evaluation and management

Patients will often visit their primary medical practitioner with orofacial pain complaints. Hence, it is important to recognize and have an understanding of these conditions to properly evaluate and potentially manage these disorders. If the practitioner is uncertain or uncomfortable with these conditions, then patient referral to a knowledgeable health care practitioner should be considered for further evaluation and management. In this article, the evaluation and management of various neuropathic, neurovascular, and vascular pains are discussed.

[Successful treatment of hemicrania continua with a combination of low-dose indomethacin and pregabalin: a case report]

A 51-year-old man complained of continuous pain lasting about 3 weeks around his forehead and left orbit-locations where pain may indicate conjunctival injection and lacrimation. Upon arrival to our hospital, his neurological examination was normal, and brain MRI showed no abnormality. The headache disappeared with indomethacin treatment (75 mg/day), and a diagnosis of hemicrania continua (HC) was established according to the International Classification of Headache Disorders, 2nd Edition. The headache returned after reducing the dose of indomethacin. After adding pregabalin (150 mg/day) to his treatment regimen, we could reduce the dose of indomethacin from 75 mg/day to 25 mg/day, which the patient tolerated well. Although HC is one of the indomethacin-responsive headaches, continuous administration can cause side effects including gastrointestinal disorders. Such side effects can decrease the tolerability of indomethacin, and may eventually lead to its reduction or discontinuation. Pregabalin can be an alternative to indomethacin for treating HC.