Definition and Causes:
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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
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
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
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
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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
Investigations and Treatment:
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The treating physician may obtain a detailed history and a
- 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,
- 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)
- 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
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:
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.
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
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.
be an option for people who do not benefit from standard therapy,
mostly involves blocking of trigeminal nerve.
Risk Factors and Prevention:
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Smokers and alcohol abusers may be more prone to cluster
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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.