Transcription
Cluster headache is a neurological disorder that presents with an intense and severe, strictly unilateral headache. Typically, the pain is located in the supraorbital, retroorbital, and temporal regions and arises from deep within the head. The headache is described as the person's worst headache ever, using comparisons such as childbirth, fractures, and renal stones. The headaches are so severe that it is known as the "suicide headache."
The pain ramps up quite quickly once it starts and typically remains for 15 to 180 minutes when untreated. During this time, patients are agitated and restless, preferring to rock in a sitting position, pace, fidget, and push their hands into the area of most pain. Cluster headache attacks can occur once every other day in the start, and increase to up to eight times a day. The attacks can have a circadian pattern with a nocturnal preference. They are usually associated with prominent cranial autonomic symptoms such as lacrimation, conjunctival injection, rhinorrhea, oral fullness, periorbital swelling, ptosis, or miosis, which again are all ipsilateral to the pain.
Cluster headaches have bouts of attacks. Cluster headaches are more common in men and can be triggered by alcohol, foods containing nitrates, and strong odors. The pathophysiology of cluster headaches is poorly understood but involves the trigeminal nerve, the nerve responsible for sensation in our face. Cluster headaches are actually part of a bigger group of headaches called trigeminal autonomic cephalgias because of the involvement of the trigeminal nerve, as well as the autonomic features associated with all these headaches. It is believed that activation of the trigeminal autonomic reflex plays a central role in the pathophysiology of cluster headaches. The thought is that stimulation of trigeminal afferents can result in cranial autonomic outflow. Pain from the cranium travels to the nucleus of the trigeminal nerve; from here, it sends pain information to the higher brain centers where we perceive pain. The ipsilateral autonomic features of cluster headaches suggest cranial parasympathetic activation. This includes lacrimation, rhinorrhea, nasal congestion, and eyelid edema, as well as sympathetic hypofunction—so inhibition of the sympathetic nerve—resulting in ptosis and miosis. These cranial autonomic symptoms are thought to result, in part, from activation of the trigeminal autonomic reflex. The activation of the trigeminal autonomic reflex is thought to be a result of activation of the hypothalamus. This makes up the trigeminal-hypothalamic pathway, which is thought to be the basically cornerstone of the pathophysiology of cluster headaches. The posterior hypothalamic region plays an important role in the pathophysiology because these headaches display the following characteristics: relapsing and remitting cause, seasonal variation, and a clock-like regularity to a single attack. This all implies involvement of a biological clock, namely the hypothalamus, in the origin of the illness. PET scan imaging has also demonstrated activation of these areas during cluster attacks and not with other headaches such as migraines.
Another theory is the vascular theory: clinical symptoms of cluster headaches are caused by neurogenic inflammation of the walls of the cavernous sinus where the sympathetic nerve and the trigeminal nerve run through. The differential diagnosis of cluster headaches is really other trigeminal autonomic cephalgias. The cluster headache itself shares many features with other trigeminal autonomic cephalgias, differing in duration and frequency. Cluster headaches typically run a 15- to 180-minute duration with a frequency of up to eight times a day. Paroxysmal hemicrania have a shorter duration but higher frequency. Then you have SUNCT and SUNA, which are terrible headaches lasting a very short duration but extremely frequent—up to 100 times a day. And then hemicrania continua, which is a constant headache that can last days. Other differential diagnoses separate to trigeminal autonomic cephalgias include migraines and trigeminal neuralgia. Investigations to order include an MRI brain.
Treatment for a cluster headache can be divided into three parts: treating an acute attack, interim treatment or bridging treatment, and once subsided, a preventative treatment. For acute treatment, if someone has an acute onset cluster headache, using high-flow oxygen via Hudson mask, for example, for 20 minutes is helpful. Also, in addition, sumatriptan subcutaneous or intranasal interim treatment can be used as an adjunct, including steroids or an occipital nerve block. Once pain is settled, preventative strategies such as verapamil or something new called calcitonin gene-related peptide monoclonal antibodies can be used.
In summary, cluster headaches are a severe, intense headache that is unilateral with associated autonomic features. The pathophysiology is thought to involve the trigeminal autonomic reflex in addition to hypothalamic activation. Treatment includes using high-flow oxygen for acute attacks and preventative strategies using verapamil.