Cluster headaches can be distinguished from other types of headache because they produce a distinctive type of pain and occur in a unique pattern. As the name suggests, they come in “clusters,” with severe pain followed by remission periods. Physicians can use these symptoms to help diagnose cluster headaches.

During an evaluation for cluster headaches, physicians typically take the patient’s medical history and perform a physical examination. Information provided during these steps can help physicians determine whether a patient’s symptoms are the result of a cluster headache or an underlying medical condition (e.g., brain tumor, aneurysm).

While collecting a patient’s medical history, physicians may ask the patient to describe symptoms. Questions in a pain assessment may focus on the characteristics of the pain, including its severity, location, frequency and duration. The patient will also be asked to describe any symptoms that accompany the pain. During the physical exam, physicians may detect one-sided eyelid drooping or reduced pupil size as part of a neurological exam.  

There is no particular test to diagnose cluster headaches, so medical history and physical examination are the only way to diagnose this condition.  Other tests may be performed to rule out other serious causes of head pain.  Physicians may use a number of methods to determine the cause of the chronic or recurrent head pain. These include:  

• MRI (magnetic resonance imaging). MRIs use a powerful magnetic field to create images of structures and organs within the body, allowing a computer to produce clear cross-sectional or three-dimensional images. This test may be ordered to examine the brain and rule out aneurysm and a number of other serious causes.
  
  
• CAT scan (computed axial tomography). This test allows for multiple x-rays to be taken from different angles around the patient. A computer analyzes the “slices” or cross-sectional images. Frequently after the first set of images is taken, the patient receives an intravenous (I.V.) injection of a contrast medium (dye) to better outline the body parts. Then a second set of images is taken. This test may be ordered to examine the brain and rule out aneurysm and a number of other serious causes of pain. 

If trigeminal neuralgia or another cranial neuralgia is also suspected, the patient may undergo a neurological exam and testing such as electromyography (EMG) and nerve conduction velocity (NCV) studies.