The condition is hallmarked by the four different types of episode/crises which are outlined below and patients may have any or all of them.
Affected babies are born red and stiff. This abates within minutes and is presumably secondary to 'the pain of birth.' No apnoeas (cessation of breathing) or bradycardias (heart beat slowness) are noted at the time of birth.
The episode which defines the phenotype is the rectal- or lower-body episode. Defecation is almost always the sole trigger in infants and children. From birth until about eight years of age these children have paroxysms (episodes) of pain following defecation. They often become restless for a few hours prior to opening their bowels. After opening their bowels they experience a severe burning pain which starts in the anus, ascends up the rectum and spreads all over their bodies but is especially severe in the abdominal area. This pain is often accompanied by apnoea and bradycardia resembling reflex anoxic seizures which lasts up to several minutes. EEG recordings during an episode show no seizure activity. Following the reflex anoxic seizures there is the classical flushing as described above.
Although children eventually outgrow defecation induced rectal episodes, affected adults fear defecating in case an episode is triggered. Adults experience similar attacks albeit rarely. Triggers include unexpected falls, fights, sexual activity and vivid dreams but not defecation.
These are the most frequent of the crises and occur in adults and children. They are mostly paroxysmal in nature (sudden attacks); however, if provoked, a change in temperature and a cold wind are the commonest triggers. Some individuals have up to twenty a day. They describe the pain as if someone is poking red hot needles into the back of one eye. This lasts for up to thirty seconds and resolves spontaneously. After this the eye waters, the pupil dilates and there is flushing on that side of the face.
Typically these occur in older children and adults and are often triggered by the first mouthful of food at a meal. Yawning is also a common trigger. Patients may experience a burning pain over the jaw area on one side of the face. It may spread round the back of the neck, and up to the ipsilateral eye (on the same side). In these instances there is an overlap with the ocular crisis. Once the pain abates the skin over the jaw area flushes and the nostril on the same side runs.