A possible role of the carotid body in the pathogenesis of cluster headache

A Review of Cardiovascular Autonomic Control in Cluster Headache

OBJECTIVE

This review aims to evaluate existing literature concerning cardiovascular autonomic function and CH. Suggestions about future research are offered and known difficulties in investigating the autonomic nervous system in cluster headache are discussed.

BACKGROUND

Little is known of the pathophysiological mechanisms behind cluster headache. Cranial autonomic features are an inherent and diagnostic feature; however, a number of studies and clinical observations support the involvement of systemic autonomic control in its pathophysiology. Further, cluster headache attacks are apparently more easily triggered during periods of parasympathetic dominance. A better understanding of this interaction may provide insight into central autonomic regulation and its role in cluster headache.

METHODS

A PubMed search was performed in April 2015 using the search terms "cluster headache," "cardiovascular," "autonomic nervous system," and "cardiac." References of identified articles were also searched for relevant articles. Studies were included if they contained data on cardiovascular or autonomic responses to autonomic tests, induced or spontaneous attacks.

RESULTS

In total, 22 studies investigating cardiac autonomic control in cluster headache were identified. Three overall categories of investigations exist: (1) Those studying changes in heart rate, blood pressure, and electrocardiographic changes; (2) those employing various clinical autonomic tests; and finally (3) those using spectral and nonlinear analysis of heart rate variability. Although not completely congruent, overall, results suggest ictal hyperactivation of the parasympathetic branch and a sympathetic deficit. Subclinical autonomic dysregulation is also present in the pain-free state.

CONCLUSION

Cardiac autonomic control is subclinically affected in cluster headache. The changes could be attributed to the suggested central dysregulation present in this disorder.

Trigeminal Autonomic Cephalalgias: Current and Future Treatments

The trigeminal autonomic cephalgias include cluster headache, paroxysmal hemicrania, and short-lasting unilateral neuralgiform headache attacks with conjunctival injection and tearing (SUNCT). The evidence for the current treatment options for each of these syndromes is considered, including oxygen, sumatriptan, and verapamil in cluster headache, indomethacin in paroxysmal hemicrania, and intravenous lidocaine and lamotrigine in SUNCT. Some treatments such as topiramate have an effect in all of these, as well as in migraine and other pain syndromes. The involvement of the hypothalamus in functional imaging studies implies that this may be a substrate for targeting treatment options in the future.

Investigation into sleep disturbance of patients suffering from cluster headache

The new discoveries relating to cluster headache (CH) encouraged the study of the relationship of the hypothalamus to respiratory physiology and its comorbidity with sleep apnoea. The question is whether the apnoeas are more frequent during REM sleep and the desaturations could be involved as triggers of the cluster attacks. Furthermore, could the connection with the hypothalamus, already proved, be responsible for an alteration in the structure of REM sleep and a chemoreceptor dysfunction. We set out to analyse when polysomnography investigation is necessary in patients with CH. We studied 37 patients suffering from episodic CH, 31 (83.8%) men and six (16.2%) women. For the control group, we selected 35 individuals, 31 (88.6%) men and four (11.4%) women. There was a greater percentage of obstructive sleep apnoea (OSA) in patients with CH (58.3%) compared with the control group (14.3%) and with the general population (2-4%). In cases of pain during sleep, the majority is deflagrated during the REM phase, following a desaturation episode. A stratified analysis of the apnoea/hypnoea index relating to body mass index (BMI) and age showed that patients with CH have 8.4 times more chance of exhibiting OSA than normal individuals (P < 0001). This risk increases to 24.38 in patients with a BMI > 25 kg/m(2) and increases to 13.5 in patients > 40 years old. Surprisingly, the risk decreases sharply in patients with a BMI < 25 kg/m(2) and who are < 40 years old. Due to the fact that polysomnography is a complex, costly and sometimes difficult examination, we suggest, in concordance with the results, that it should be carried out routinely in patients with CH that exhibit a BMI of > 25 kg/m(2) and/or in patients who are > 40 years of age.

Obstructive sleep apnea and cluster headache

A patient with cluster headache often wakes from sleep. The relationship to sleep apnea has been described. This study sought to confirm the relationship cluster may have with sleep apnea.

METHODS

Thirty-nine consecutive patients diagnosed with episodic cluster headache according to the International Headache Society (IHS) criteria were sent for polysomnographic studies. All patients were in an active phase when they were in the study. Patients were told of the proposed relationship and were allowed to choose a sleep laboratory close to their home.

RESULTS

Thirty-one patients with episodic cluster headache completed an overnight polysomnographic study. Twenty-three were male and eight female. The average age was 51 years (range 33 to 78 years). The average weight was 173 pounds (range 117 to 260 pounds). A total of 80.64% had sleep apnea (25/31). Average respiratory depression index (RDI) was 19.0 (SD 14.6) with 6 patients having no apnea, 10 having mild, 11 having moderate, and 4 having severe apnea (RDI < 5 = none; RDI 5 to 20 mild; RDI 20 to 40 moderate; RDI > 40 severe). Oxygen saturation decreased on average to 88.4% SD 4.5. Sleep efficiency was 76.2% (SD 13.4).

CONCLUSIONS

The data closely approximate those of Chervin et al, where 80% had RDI > 5. The relationship sleep apnea has in the perpetuation or precipitation of cluster headache is still to be determined. There are some reports that treatment stops the cluster but there is no prospective study. The high incidence (80.64%) seen in this population suggests the cluster patient should receive a sleep evaluation and perhaps intervention with continuous positive airway pressure (CPAP) or an appropriate dental device.

Cluster headache associated with sleep apnoea

This study of sleep changes in patients with cluster headache (CH) was conducted in view of the nocturnal predominance of this condition, the efficacy of oxygen and the fact that the attacks follow oxygen desaturation. Proposed mechanisms include impairment of carotid body activity secondary to hypothalamic vasomotor regulatory dysfunction. Sixteen patients with episodic CH and 29 healthy volunteers underwent nocturnal polysomnography. Five (31.3%) patients with episodic CH were found to have sleep apnoea (SA). Two patients with SA experienced two attacks during the study period. The attacks followed episodes of oxygen desaturation and were associated with REM sleep. In two patients with SA and CH, treatment with continuous positive airway pressure abolished their oxygen desaturation, sleep apnoeas and headaches. Our study confirmed the high percentage of CH associated with SA. We suggest that oxygen desaturation may be a trigger factor in some patients and play a role in the pathogenesis of CH.

Cluster headaches and sleep disorders

Cluster headaches are characterized by unilateral paroxysmal attacks of severe pain with associated symptoms. The headaches occur during particular sleep stages and are associated with other chronobiologic factors. Several sleep disorders have been associated with the occurrence of cluster headache; multiple hormonal influences affect the relationship between sleep and headache. Melatonin and other treatments that affect circadian rhythm have been suggested for the treatment of cluster headache. Obstructive sleep apnea can occur in patients with cluster headache; attempts to treat one disorder may influence the other. Sleep disorders such as insomnia and narcolepsy also may be associated with and influence cluster headaches. This article examines the relationship between the various sleep disorders and cluster headache, and reviews current research. Normal and abnormal sleep and details of treatments for specific sleep disorders that may decrease the frequency and severity of cluster headaches also are discussed. The relationship between obstructive sleep apnea, which is the most common sleep disorder, and cluster headache is discussed in detail.

Diagnosis and treatment of cluster headache

This article classifies cluster headaches as distinct from other types of headaches and gives guidelines for diagnosis and treatment. Explanations of the pathophysiology and pathogenesis of cluster headaches are included also.

Onset of nocturnal attacks of chronic cluster headache in relation to sleep stages

Nocturnal attacks are symptomatic of numerous primary headache syndromes. It has proven possible to verify, with polygraphic sleep recordings, a strict correlation between the onset of headache attacks and the rapid eye movements (REM) stage for migraineurs, patients with chronic paroxysmal hemicrania and cluster headache (CH). The purpose of this study was to investigate the correlation between attack onset of chronic CH and sleep stages, the REM stage in particular. Nine patients from our headache outpatient service with a diagnosis of CH were examined in this study. All medication was discontinued at least one week prior to sleep polygraphias, which were conducted in a sleep laboratory on two consecutive nights. Any attacks were treated with oxygen inhalation during the drug-free period. EEG, EMG, and EOG were continuously monitored during the sleep polygraphias. Eight patients had 25 CH attacks during 12 of the 17 nights recorded. Only three of these patients had arousals with attacks in the REM stage and these amounted to five of the 25 recorded attacks. Eleven attacks were in stage 2, four in stage 1 and two in stage 3. These results correlate with recent findings according to which headache attacks were often related to REM in episodic CH, but rarely in the chronic type. Whether or not different pathogenic mechanisms are involved in the episodic and the chronic type of CH is a matter for further discussion.