Cluster Headache
Definition &CausesSymptomsInvestigations & TreatmentsRisk Factors & PreventionOutcome
Definition and Causes:


Cluster headaches are one of the most severe and intense headaches, when compared with migraine attacks. It is a brief, intolerable pain of unknown cause; surrounding the area around one eye (left or right).

Headaches tend to recur over a period of few weeks (often ~2-8 weeks), followed by headache free period of months before they occur again. The episodes typically occur around the same time each day, often awakening a person within 1 to 2 hours after going to bed. Each episode may last from minutes upto ~ 3 hrs. Some may experience 2-3 episodes at different times each day.

Nocturnal attacks can be more severe than the daytime episodes.

Cluster headaches are uncommon and often affect individuals less than 30 years.



The actual cause of cluster headaches is unknown. One theory is the activation of a neural (nerve) pathways in the base of the brain. The nerve that provides sensation to the face is called the trigeminal nerve; so named because it has three main branches. There is one trigeminal nerve on each side of the face. Each trigeminal nerve originates in the brain and runs out to the face.

Activation of trigeminal nerves which appears to come from the deeper part of the brain called hypothalamus, and is home to our "internal biologic clock" which regulates our sleep and wake pattern.

Recent imaging studies have shown activation or stimulation of the hypothalamus during a cluster attack; this may well explain why the attacks occur around the same time in each day.

In addition to pain, activation of the trigeminal nerve stimulates another group of nerves which causes; redness and tears of the eyes, with nasal congestion/draining associated with these attacks.


Back to Top

Pain is of sudden onset, comes without warning, typically on one side of the face (around the eye); may start as a burning sensation and peaks within minutes lasting for 15-180 mins.

The attacks are often nocturnal awakening a person from sleep.

The pain almost always begins in one eye and on one side of the face; while in a small minority the pain switches to the opposite side during the next cluster

The pain has been described as "excruciating," "explosive," and "deep." Some report a stabbing eye pain with or without sensation of an electrical-shock, lasting for a few seconds, and a deeper aching sensation that last for 30 min or more.


Summary of main symptoms:

  • Affects one side of the face
  • Excruciating pain around same time daily
  • Eye redness
  • Stuffiness of nostril
  • Facial swelling, flushing, and sweating.


Patients should seek medical attention by a physician with expertise in pain management and/or headaches.

Note: Prompt medical attention (including ER visit) may be required if:

  • Unbearable, uncontrolled pain that is not relieved by usual pain killers or prescribed medication
  • Difficulty with eating/drinking due to pain
  • Undesirable side effects from your medication such as, drowsiness, nausea and vomiting
  • Change in severity and frequency of attacks


Back to Top
Investigations and Treatment:

The treating physician may obtain a detailed history and a physical examination.

  • History: The doctor will inquire about
    • The nature of pain
    • Severity and intensity
    • Location /frequency/duration
    • Pain is new or longstanding
    • Intermittent or persistent pain
    • Association with nausea or vomiting
    • Triggers, i.e. if worsened by chewing, speaking, weather, temperature etc.
  • Physical exam might include:
    • Blood pressure, heart rate, temperature. A neurological examination may also be conducted



Most patients with a clear description of headache, that improves with pain medications and who has a normal physical examination, may not require any specific investigations. However, if there is a suspicion or concern of some other underlying cause, then patients may be requested to have brain imaging.

Computed Tomography (CT) Scan:

  • This device uses x-rays. Patients will lie on a table with the head placed inside of the scanner (resembles a large donut). Computer analyse detailed x-ray images of the brain which are obtained by the scanner. The scanning time is usually very rapid (~1 minute). In special circumstances a dye might be injected into the veins just before the scan (CT with contrast). This can sometimes help to identify areas of infection (abscesses), inflammation, tumors etc.

CT Angiogram (CTA):

  • A CT scan of the brain is completed after dye has been injected into the veins (CT with contrast), however, the computer analysis focuses on the arteries (a type of blood vessel) in and around the brain. This can be used to help identify aneurysms.

Magnetic Resonance Imaging (MRI):

  • This does not use x-rays. Instead MRI uses magnetic fields over the body. The device looks like a long cylindrical tube. Patients will lie on a table that slides into the hollow tube. Computer analysis of magnetic fields within the machine can generate images of the internal structures of the body's organs, including the brain. MRI of the brain will show the normal structures, plus any area(s) of brain injury caused by the inflammation, tumors, previous stroke etc. Patients must lie still inside the MRI machine for several minutes. In some circumstances a dye might be injected into the veins (enhanced MRI) just before the scan to help improve detection of abnormalities. Patients who complain of claustrophobia or discomfort may be given a mild sedative to help relax prior to MRI scanning

Cerebrospinal fluid (CSF) analysis:

Lumbar Puncture/Spinal tap

  • This procedure is not routinely used in the assessment of headache, but may be used in some circumstances, e.g. suspicion of brain infection or leakage of blood from an aneurysm. The purpose is to extract a small amount of fluid called cerebrospinal fluid (CSF) from the patient's spine in the low back (lumbar) area and send for analysis. During the procedure the physician will clean and drape the lumbar area. A local anaesthetic is administered over the skin where the needle is to be placed. Since the spinal cord does not extend down into the lower lumbar region there is little or no chance of causing injury to the spinal cord. The extracted CSF is sent to the laboratory for analysis and is checked for protein, glucose, red and white blood cells and infectious organisms such as bacteria and viruses. In some circumstances CSF is used to check for cancer cells (if required)



Involves two types of interventions as follows:

Abortive Therapy:

As the name suggests, this therapy is designed to abort a headache once it has started. Medications that may relieve symptoms include "triptan" agents; along with oxygen inhalation through a face mask for twenty minutes.

Triptan agents: Usually more effective than over the counter formulations, and are used as needed.


Preventive Therapy:

These medications are prescribed to shorten the length of the cluster headache period as well as decrease the severity of the headaches. Medications options includes: verapamil, lithium, divalproex sodium, prednisone (only short courses), and ergotamine tartrate.


Note: While there are potential side effects from using these medications, there are also beneficial effects. Consequently, the treating physician will assess the side effect risks versus the benefits in controlling symptoms and improving quality of life (risk versus benefit ratio), before recommending treatment. If the patient has other medical conditions or using other medications, these are taken into account when prescribing medications. Patient is advised to take note of and report potential side effects to the treating physician.

Nerve Block:

May be an option for people who do not benefit from standard therapy, mostly involves blocking of trigeminal nerve.


Back to Top
Risk Factors and Prevention:

Smokers and alcohol abusers may be more prone to cluster headaches.


Back to Top

Although there is no cure for cluster headaches, careful monitoring of symptoms, and use of both abortive (for immediate relief) and prophylactic medical therapy can help control cluster attacks and improve quality of life.


Back to Top
Copyright © 2011-2019 Innovate R&D

educate Are you a Healthcare professional or patient?

Healthcare Professionals would include: Physicians (MD,OD), Physician assistants, Nurses, Pharmacists,Allied Health Workers (PT, OT, SLP, etc), Chiropractors, Paramedics, Optometrists, Dentists, Podiatrists etc, and students within these disciplines.

educate ** You are required to register **

eDucate is committed to optimizing the delivery of health information across the Healthcare continuum. To this end eDucate uses a wide array of learning tools, including Webinars, Quick Review Charts, Graphs, Brochures, Videos and Slide Presentations.

Professional Membership Benefits include free access to all archived and upcoming Webinars:

educate DISCLAIMER: This website is owned and operated by The Innovate Research and Development LP (Innovate R&D). All references herein to Innovate R&D shall be deemed to include any subsidiary, affiliate, associate or successor corporation of Innovate R&D. By entering and using this site, you agree to the "Terms of Use"for this website. If you do not agree to these terms and conditions then exit from this site immediately. Although Innovate R&D updates this website regularly with material believed to be accurate at the time of posting, Innovate R&D does not guarantee the accuracy, completeness, timeliness or currency of the material and consequently Innovate R&D expressly disclaims any liability for errors or omissions in the material contained in the website. The Innovate R&D website and all contents are provided as-is, and all representations and warranties, express or implied, relating to the website or the content are disclaimed, including any implied warranty of merchantability, fitness for a particular purpose or non-infringement, as well as any warranty of quality, functionality, accuracy, currency, completeness, reliability, operability, use performance or absence of viruses. In no way or event will Innovate R&D or any party that has been involved in the creation, production, promotion and marketing be liable to you or any other party for perceived direct or indirect damages. You assume all responsibility and risk of loss resulting from the use of our website.