Confusional migraine appears to be a rare subtype of migraine. About half these cases are associated with mild brain trauma. The onset of confusional migraine may almost immediately follow an impact to the head and the symptoms can also disappear within 1-12 hours.
The study of confusional migraine is interesting as it points to a common pathophysiology found in migraine and mild brain injury. It is thought that mild brain injury causes a depression or suppression of neural activity, which spreads in a circular pattern from the site of the impact across the hemisphere concerned. This transient wave of neuronal depolarisation - the cortical spreading depression - is believed to be the pathophysiological mechanism underlying the clinical phenomenon of migraine aura. The aura symptoms, such as scotoma, are also associated with blood flow changes or hypoperfusion. Speculation has, thus, arisen as to whether confusional migraine is actually an indication of mild brain injury, which has a similar pathophysiology. Figure 1.2 compares the multitude of neuro-cortical dysfunctions that can be found in both migraine and mild brain injury. Another explanation for the onset of confusional migraine - and probably also posttraumatic migraines - could be the development of localised cerebral oedema, which occur due to increased vascular permeability following a mild brain injury. As described above, neurological migraine attacks affect the functioning of many areas of the cortex as well as the hippocampus and brain stem. This ties in with explanations of mild brain injury and concussion as transient micro-neurological and ischemic pathologies, which affect the integrity of brain systems and result in a concert of posttraumatic pain and concussion symptoms.
Figure 1.2 Similarities in pathology: mild brain injury and migraine. Cervicogenic headache
Cervicogenic headache is very common following brain injury. This is due to the force of the blow' to the head also affecting the musculoskeletal regions of the neck and upper spine. In a typical car accident, the head bends rapidly backwards, causing the mouth and jaw to open. This can lead to jaw' dislocation and disc injuries, which can be associated with cervical myofascial pain, cervical ligament strain, cervical disc protrusion and upper cervical joint injury (C2, C3). Cervicogenic headache may also be caused by direct injury to a number of nerves, which can result in neuralgic pain.
Headache after an injury to the features of the head and brain may also occur in the case of lesions to the soft tissues or when there is scar formation. The site of the injury is often sensitive to finger pressure. Neuralgic headaches may develop following local blunt trauma or penetrating scalp injury, resulting in damage to nerve endings. Types of neuralgic headaches include occipital, trigeminal, scalp laceration and supraorbital neuralgias. Allodynia is characterised by hypersensitivity and localised painful sensory disturbances.
There are a number of other reasons for the development of headache disorders following brain injury. It is useful to be observant of painkiller overuse headaches and headaches linked to the side effects of other medications. In addition, somatoform headaches, malingering and pain in association with any somatic or mental health conditions should be taken into account.
Patients may have different types of headaches at different times or a variety of symptoms together that are characteristic of more than one type of headache.
Initially, it is important for a medical professional to conduct an adequate physical examination of each patient in order to identify the specific headache subtype and to prescribe the correct treatment. The headache therapist will also benefit from a clear understanding of the various headache subtypes outlined above in their formulation of a clear description of the symptom profile. This will facilitate the design and implementation of the most appropriate and thus most effective therapy programme, as suggested in the later chapters of this book.