Clinical history. It is the key element in the diagnosis of headaches, in order to define the characteristics of the pain (continuous, pulsatile), the location (hemicranial, frontal, periocular or in the nape of the neck), the duration, if it is episodic, the intensity of the pain, the way it starts (sudden or gradual), time of onset (when has the headache appeared), if there are associated symptoms like vegetative state (nausea and vomiting), photophobia, phonophobia, neurological symptoms that may precede the pain, such as changes in vision (bright light, halos, or fortification spectra, black spots, loss of vision), in sensitivity, in speech, or in strength. It also should be asked if there are factors that aggravate it (menstruation, recently starting to take oral contraceptives or other drugs, stress, changes in sleep pattern, red wine, Chinese restaurant spices), those that trigger it (trigger points, such as pressure in a specific point of the face, brushing teeth, biting), or those that alleviate it. It is important to know if there is a family history of cephalalgia.
Physical and neurological examination. In order to detect changes that rule out secondary causes of cephalalgia, tests are used, such as a back of the eye examination to evaluate the presence of a swelling or oedema of the papilla (a prominence that forms the entrance to the back of the eye) that suggests the presence of intracranial pressure.
They are performed when a secondary cause is suspected or needs to be ruled out:
Laboratory tests. When there is the suspicion of an arteritis of the temporal artery, which is more common in women over 60 years-old.
Neuroimaging tests. The two main ones are cranial computed tomography (cranial CT) and cranial magnetic resonance (cranial MR). These are performed when the patient has an atypical headache, epileptic seizures, or signs/symptoms of a neurological focus.
Cranial CT. It can detect the majority of the conditions that can cause secondary headaches. It is a rapid test, and of first choice in emergency situations. It is also the preferred test for assessing acute haemorrhages, skull injuries, and bone anomalies.
Cranial MR. It provides a better characterisation of the changes observed in the CT, and sometimes can detect small lesions that are not seen in an initial cranial CT scan, such as multiple micro-infarctions or micro-haemorrhages in cerebral venous thrombosis, or in cerebral vasculitis (inflammation of the blood vessels).
Angio-MR and Angio-CT.They are special MR or CT techniques with intravenous contrast that are useful for studying blood vessels (angiology) and their anomalies, such as aneurysms, other vascular malformations, or cerebral venous thrombosis. They are non-invasive and safe tests. Some MR techniques and sequences enable angiology studies to be performed without contrast.
Lumbar puncture. It helps to identify if there is an inflammation or infection in the cerebrospinal fluid (CSF) that surrounds the brain and the spinal cord, and to measure its pressure. The main indications are when the patient has a thunderclap headache (one that reaches its maximum intensity in one minute) with no evidence of bleeding in the CT, persistent headache of recent appearance with a normal neuro-image, suspicion of infectious meningeal or inflammatory encephalitis (headache, fever, change in level of consciousness, neck stiffness), meningeal infiltration processes due to cancer, or idiopathic intracranial pressure (increase in the pressure of the cerebrospinal fluid).
Isotope cisternography and CT-myelography.They are used, exceptionally, in the study of cerebrospinal fluid (CSF) hypotension in order to detect CSF leaks, generally after skull trauma.