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  • Writer's pictureDr. Harold Pierre

Cluster Headaches: What You Need to Know

Updated: Apr 26

Cluster Headaches: What you Need to Know in 2023

Cluster headaches are excruciatingly painful headaches that affect approximately 1 in 1000 people. Characterized by severe unilateral head pain and associated autonomic symptoms, cluster headaches are relatively rare but can be debilitating. This guide provides an overview of the symptoms, causes, diagnosis, and treatment options for effectively managing cluster headaches.

What Exactly Are Cluster Headaches?

Cluster headaches are classified as a type of primary headache disorder. They are not caused by underlying medical conditions but originate within the head itself. The term "cluster" refers to the tendency for these headaches to occur in cyclical patterns or clusters.

Cluster headaches occur in two primary forms:

Episodic Cluster Headaches

Episodic cluster headaches are the most common type, making up about 80-90% of cases. These involve cyclical headache periods called cluster periods which last from 2 weeks to 3 months, alternating with headache-free remission periods lasting months or longer.

During a cluster period, episodic cluster headache attacks strike once or more times per day, often at the same times each day. The cluster bout may happen just once or recur multiple times per year. With effective treatments, many patients with episodic cluster headaches experience minimal disruption during their periods between clusters.

Chronic Cluster Headaches

In the chronic form, cluster headache attacks occur for more than one year without remission or with remissions lasting less than 3 months. There are no long breaks from the headaches.

Chronic cluster headaches may begin as episodic but transform into the chronic pattern over time. Patients require continuous preventive treatment to try reducing headache frequency and disability.

The chronic form of cluster headaches can be very difficult to fully control. Patients may suffer severe impairment in work, relationships, and quality of life. While the pain may be severe, a cluster headache is not life threatening.

Some key features that define cluster headaches:

  • Severity - The pain is excruciating, rated as one of the most intensely painful conditions. Patients describe it as burning, stabbing, or shock-like.

  • Laterality - The pain always occurs on one side of the head, typically around the eye, temple, or forehead region.

  • Duration - Attacks last 15 minutes to 3 hours when untreated. The headache phase tends to be shorter than migraines.

  • Frequency - During a cluster period, attacks often strike once or more times per day.

  • Autonomic symptoms - Teary eye, congested nose, or droopy eyelid may occur on the affected side.

  • Restlessness - Many patients feel agitated and need to pace during an attack.

  • Triggers - Alcohol, strong odors, heat, or exertion can trigger attacks in some people.

  • Timing - Attacks follow a circadian pattern, often striking at night.

So in summary, cluster headaches cause severe head pain along with cranial autonomic features and agitation, recurring frequently in cyclical time patterns.

man suffering from headache

What Causes Cluster Headaches?

Experts don't know what causes cluster headaches. They were once thought to be vascular headaches due to arterial dilation, but newer research implicates dysfunction in the hypothalamus and trigeminovascular system as likely contributors.

Some theories on the origin of cluster headache attacks:

  • The hypothalamus regulates circadian rhythms and may trigger cluster periods. PET scans show hypothalamic activation during attacks.

  • The trigeminal nerve is responsible for conducting sensation of the face, scalp and controls chewing.

  • The trigeminovascular system is a neural pathway that connects the trigeminal nerve to blood vessels in the brain's meninges.

  • The trigeminocervical complex is where nerves from the trigeminal nerve and nerves from the cervical spine meet.

  • Overactive trigeminal nerves relay pain signals from the head to the brainstem trigeminocervical complex. This activates the cranial parasympathetic nervous system.

  • Inflammation and dilation of arteries in the brain may initiate the cascade leading to head pain.

  • Genetics may play a role, as cluster headaches sometimes run in families.

While the sequence of events is unclear, cluster headaches may result from abnormal signaling between the hypothalamus, trigeminal nerves, and cranial blood vessels. But more research is needed on the precise causes and pathology.

Who Gets Cluster Headaches?

Cluster headaches most often start between ages 20 and 40, but any age group can be affected. Other patterns noted:

  • Men are impacted 3-4 times more often than women.

  • Tobacco smokers have an increased risk.

  • Patients often have a personal or family history of migraines.

  • Remission during pregnancy is common. Attacks may also improve with menopause.

  • No definitive cause has been identified, though genetics likely contributes.

Overall, cluster headaches remain very rare, affecting an estimated 0.1% of the population. While more research is still needed, hypothalamic and trigeminal dysfunction along with vascular and inflammatory changes appear central to the disorder.

What Are the Symptoms of Cluster Headaches?

The primary symptom is a severe, piercing headache on one side of the head. Characteristic features of a cluster headache include:

  • Location - Pain centers around the eye, temple, or forehead on one side. It may radiate to other areas like the face, neck, or shoulder.

  • Quality - Patients describe a sharp, burning, drilling, or stabbing sensation. The pain rapidly peaks in intensity.

  • Severity - The headaches cause severe pain. They are typically rated among the most painful conditions, with pain scores of 8-10 out of 10.

  • Duration - If untreated, cluster headaches usually last 15 minutes to 3 hours, with most under 90 minutes. The headache phase tends to be shorter than migraine.

  • Frequency - During a cluster period, attacks occur once every other day up to 8 times per day. More than 5 per day is rare.

  • Autonomic symptoms - Teary eyes, swollen eyelid, stuffy nose, or facial sweating may occur on the painful side. The pupil may be constricted.

  • Restlessness - More than two-thirds of patients have agitation and an urgent need to move during headaches.

  • Timing and triggers - Attacks follow a circadian pattern. Most happen at night, often waking the person. Triggers like alcohol, heat, strong scents, or exertion can precipitate attacks in some.

So in summary, the hallmark of a cluster headache is severe unilateral head pain with cranial autonomic symptoms. Attacks are frequent, short-lived, and lead to agitation.

How Are Cluster Headaches Diagnosed?

Cluster headaches are usually diagnosed based on the typical clinical presentation. Investigations help rule out secondary causes like infections, vascular disorders, or tumors. Common tests include:

  • Medical history - Details about headache patterns, triggers, family history of headaches, and associated symptoms.

  • Neurological exam - To assess nerve function and check for other problems.

  • Head MRI or CT scan - To rule out other headache causes like mass lesions or aneurysms. Findings are typically normal.

  • Blood tests - To check for potential inflammatory or infectious causes.

  • Keeping a headache diary for 1-2 months aids diagnosis by revealing attack frequency, timing, triggers, and response to treatments tried.

The diagnosis can be confirmed by meeting the International Classification of Headache Disorders (ICHD-3) criteria for cluster headache. A neurologist or headache specialist should evaluate persistent or worsening headaches.

How Are Cluster Headaches Treated and Managed in Detail?

Cluster headaches are highly disruptive and difficult to treat. A multifaceted therapeutic approach is often needed to both rapidly abort acute attacks and prevent recurrence. This section provides more in-depth detail on the various medications, procedures, devices, and other therapies used for managing cluster headaches.

Abortive Medications

Abortive medications aim to stop an attack quickly once it starts. The mainstays for acute cluster headache treatment are injectable sumatriptan and high-flow oxygen:

  • Sumatriptan – This serotonin agonist is considered first-line. Sumatriptan injection (6 mg subcutaneous) or nasal spray (20 mg) can relieve pain within 15 minutes in many patients. It works by inhibiting trigeminal nerve transmission of headache pain signals and cranial vasodilation. It helps with cluster headaches or migraine headaches. Side effects may include dizziness, fatigue, and chest or neck discomfort.

  • Oxygen – Inhaling high flow 100% oxygen (12 L/min) via face mask for 15-20 minutes aborts attacks for most patients. It may work by reducing inflammation and cranial blood vessel dilation. Drawbacks include limited portability of oxygen tanks and risk of rebound headaches.

  • Octreotide - an injectable synthetic somatostatin analog that is sometimes used as an acute treatment for cluster headaches. It is thought to interrupt the activation of the trigeminal-autonomic reflex which mediates cranial parasympathetic symptoms during cluster headache attacks. Octreotide dampens trigeminal nerve excitation and inhibits the release of vasoactive neuropeptides involved in headache pain signaling. Subcutaneous octreotide injection rapidly reaches peak plasma levels, allowing it to abort an acute cluster headache attack within minutes in some patients.

Other fast-acting options that may be tried include intranasal zolmitriptan spray, high dose oral triptans like eletriptan or frovatriptan, intranasal lidocaine, and intranasal ketamine. Having an individualized abortive therapy plan is key to rapidly treating breakthrough headaches.

Transitional (Bridge) Treatments

Transitional or bridge therapies are used short-term at the start of a cluster period to prevent attacks until long-term preventives become effective.

  • Corticosteroids – A short prednisone taper (starting at 60-100 mg/day) or suboccipital steroid injection can suppress headaches temporarily. They likely work by reducing neurogenic inflammation in the trigeminal system. Side effects like insomnia, hyperglycemia, or mood changes may occur.

  • Greater occipital nerve blocks – Injecting a local anesthetic and steroid around the occipital nerves can provide headache relief lasting weeks or more for some. Risks include hair loss or infection at the injection site. Repeated blocks may be needed.

These brief therapies can provide attack protection while starting or optimizing preventive medications when cluster headaches first emerge. They are not used long-term due to adverse effects.

Preventive Medications

Daily preventive medications taken during the full cluster period aim to reduce headache frequency, severity, and disability. Common options include:

  • Verapamil – This calcium channel blocker is considered first-line for cluster headache prevention. Doses of 240-960 mg daily may be needed. It likely works by inhibiting cranial vasodilation and reducing trigeminal nerve excitability. Potential side effects include dizziness, constipation, low blood pressure and heart block.

  • Lithium – Lithium doses of 600-1500 mg daily may help prevent attacks. Frequent monitoring of blood levels is needed to avoid toxicity. Nausea, tremor, fatigue and increased urination are potential side effects. It may suppress hypothalamic activation involved in cluster headache.

  • Topiramate – This anticonvulsant can be effective for prevention at doses up to 400 mg daily. Side effects may include cognitive problems, fatigue, nausea, weight loss, kidney stones or metabolic acidosis.

  • Melatonin – At doses of 10-15 mg nightly, melatonin reduces headache frequency for some patients with minimal side effects besides drowsiness. Its circadian rhythm effects may benefit cluster headaches.

  • Galcanezumab – This monoclonal antibody blocks the action of CGRP, a peptide involved in headache pain signaling. Injections of 120 or 240 mg monthly significantly reduced weekly headache frequency compared to placebo in a study of episodic cluster headache patients. It was ineffective for chronic cluster headaches. Galcanezumab may work by inhibiting CGRP release from trigeminal neurons to suppress attacks. Potential side effects include injection site reactions. Its role compared to other preventives requires further study.

  • Baclofen – Baclofen is a GABA-B receptor agonist that may reduce cluster headache frequency at doses of 15-30 mg daily in divided doses. Its mechanism of action in cluster headaches is not fully understood but may involve inhibition of trigeminal activation. Drowsiness, fatigue, and muscle weakness are potential side effects. Evidence for its use is limited to open-label studies but baclofen offers a treatment option for patients intolerant to first-line preventives. More research is still needed.

  • Valproic Acid – Valproic acid is an anticonvulsant that has been used off-label for cluster headache prevention at doses ranging from 500-2000 mg daily. It may work by enhancing GABA activity and inhibiting sodium and calcium channels involved in pain signaling. Side effects can include nausea, tremor, weight gain, hair loss and liver toxicity. Small open-label studies show mixed results for efficacy.

Other options sometimes used include gabapentin and corticosteroids, but evidence is limited. Having access to multiple preventive medication classes is beneficial since patient responses vary.

Young handsome business man with hand on head for pain in head because of stress. Suffering from Cluster headache

What Neuromodulation Devices Are Used for Cluster Headaches?

Neuromodulation techniques use electrical stimulation to modulate misfiring pain pathways and treat cluster headaches. Non-invasive and invasive nerve stimulators may help patients refractory to medications.

  • Non-invasive vagus nerve stimulation – This handheld device (gammaCoreTM )delivers stimulations to the neck to activate the vagus nerve. It may inhibit attacks through effects on the trigeminal and cranial autonomic pathways. Twice daily preventive use has the best evidence in chronic cluster headache.

  • Sphenopalatine ganglion stimulation – An implanted device stimulates the sphenopalatine ganglion nerve bundle, which is part of the trigeminal autonomic reflex arc. This may reduce cluster headache frequency and provide acute attack relief for some chronic cluster headache patients.

  • Occipital nerve stimulation – Electrodes implanted over the occipital nerve give chronic stimulation to inhibit headache attacks. It may work by modulating pain signaling in the trigeminocervical complex. Benefits are most evident long-term in chronic refractory cluster patients.

Though invasive, nerve stimulation approaches may be very helpful for patients not responding adequately to medications.

Other Therapies

A number of non-traditional therapies have also been tried specifically for cluster headache management with varying success:

  • Ketamine – Sub-anesthetic intravenous ketamine infusions aim to “reset” aberrant pain pathways in chronic headaches. It may work by blocking NMDA receptors and glutamate signaling. Ketamine may be given intranasal or sublingual as another option.

  • Lidocaine Infusions – Slow intravenous lidocaine administration has demonstrated preventive effects lasting weeks or more for episodic cluster headaches and chronic cluster headaches in open-label studies. How it provides benefit is unknown but may involve stabilizing neurotransmitters, inhibiting ion channels, and anti-inflammatory effects.

  • Intravenous Magnesium Infusions - Administering high dose (1 gram) magnesium sulfate intravenously can help abort an acute cluster headache for some patients. It may work by blocking glutamate signaling involved in migraine and cluster headaches. However, this seems to work best in patients with low serum magnesium levels.

  • Psilocybin – In small studies, supervised dosing with psilocybin-containing mushrooms shows promise for rapidly aborting acute cluster attacks and maintaining headache remission when used prophylactically. Its serotonergic, anti-inflammatory and hypothalamic effects may modulate chronic cluster headache.

  • Greater occipital nerve blockade – Repeated injections of local anesthetic and steroid around the greater occipital nerve can have protective effects lasting weeks to months for some cluster headache patients. Evidence is limited but larger trials are underway.

  • Stellate ganglion block - Injecting local anesthetic into the stellate ganglion, which is part of the sympathetic nervous system, can provide pain relief lasting hours to days for some chronic cluster headache patients. It may work by disrupting the trigeminal-autonomic reflex involved in cranial parasympathetic activation during attacks. Evidence is limited but stellate ganglion blocks may reduce attack frequency as a bridge therapy while starting preventives.

  • Low-Dose Naltrexone - Naltrexone is an opioid receptor antagonist that at low doses of 4.5mg daily may have anti-inflammatory and neuromodulatory pain relieving properties. Through effects on microglia and central opioid pathways, it has demonstrated reductions in headache frequency for a subset of patients in small open-label cluster headache trials. Side effects like insomnia, vivid dreams and GI upset are usually temporary.

Other non-pharmacological therapies like cognitive behavioral therapy, stress reduction techniques, acupuncture, capsaicin nasal sprays and more continue to be explored as potential additions to standard cluster headache management. A patient-centered integrative treatment approach is recommended.

In summary, effective cluster headache management requires a toolbox of treatment options - abortive, transitional, and preventive medications, neuromodulation devices, and complementary techniques. An individualized approach combining modalities tailored to each patient offers the best chance of limiting this disabling disorder. Ongoing research continues to provide more therapies and hope for gaining control over stubborn cluster headaches.

What Is the Prognosis for People with Cluster Headaches?

The long-term outlook for cluster headaches depends on whether the condition is episodic or chronic:

  • Episodic - This is the more common type, making up 80-90% of cases. Cluster periods or "bouts" lasting weeks or months alternate with remission periods of months or years. With proper treatment, many patients experience minimal disruption.

  • Chronic - In about 10-15% of patients, attacks occur for more than 1 year without remission or with remissions lasting less than 3 months. Preventive treatment is often needed continuously. The condition can be more debilitating with greater impact on work, relationships, and quality of life.

  • With adequate treatment, cluster headaches typically do not result in serious complications or long term consequences. Patients may have anxiety or depression associated with the severity and unpredictability of attacks. Very rare secondary problems like venous thrombosis have been reported.

Overall, the prognosis for cluster headache is generally good with proper medical management. But the chronic form can be difficult to fully control and is disabling for some patients. More research is needed to better understand this devastating disorder.

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In Conclusion

Cluster headaches can be extremely painful but various treatment options exist to help manage symptoms. Being prepared with effective abortive and preventive medications and avoiding potential headache triggers can help patients better cope with cluster headache periods. Work closely with your medical provider to find an optimal treatment plan for your particular headache pattern. With an individualized management approach, the debilitating effects of cluster headaches can often be minimized so patients can still live well.

Frequently Asked Questions About Cluster Headaches

What triggers cluster headaches? Alcohol, strong odors, heat, exertion, or strong emotions can trigger attacks during a cluster period in susceptible individuals. Keeping a headache diary can help identify personal headache triggers.

Is there a cure for cluster headaches? Currently there is no medical cure for cluster headaches. Available treatments aim to abort acute attacks and prevent recurrent headaches. Avoiding triggers and following a healthy lifestyle may help some patients manage clusters.

Are cluster headaches serious or life threatening? The severity of pain is very high with cluster headaches but the headaches themselves are not life threatening or a sign of serious underlying illness in most patients. Very rarely, secondary headaches with similar features can stem from infectious or vascular causes.

How are cluster headaches different from migraines? Compared to migraines, cluster headaches cause more severe pain but for a much shorter duration. Migraines are common while cluster headaches are rare. Cluster headaches also recur more frequently during a bout, happen at the same time daily, and cause agitation and cranial autonomic symptoms. Cluster headaches tend to occur in men while migraines are more common in women.

How are cluster headaches treated during pregnancy? Pregnancy often induces natural remission of cluster headaches. If needed, oxygen, magnesium, and some pain relievers are considered safe treatment options during pregnancy. Preventive medications often need to be stopped prior to conception.

When should I see a doctor for cluster headaches? It’s important to consult a doctor if you experience any severe recurrent headache patterns for proper diagnosis and treatment. Keep notes on your headache features, triggers, frequency, and response to any medications tried to assist your physician.

About the author:

Dr. Harold Pierre is a board-certified anesthesiologist and addiction medicine specialist with over 20 years of experience. He is board-certified by the American Board of Anesthesiology and the American Board of Preventive Medicine.

This website is provided for educational and informational purposes only and does not constitute providing medical advice or professional services. The information provided should not be used for diagnosing or treating a health problem or disease, and those seeking personal medical advice should consult with a licensed physician or another qualified medical professional. Never disregard professional medical advice or delay in seeking it because of something you have read on this website.

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