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Paroxysmal Extreme Pain disorder

Also known as: Familial Rectal Pain

Background

Paroxysmal extreme pain disorder is a rare disorder of abnormal pain sensation which presents in the first year of life with episodes of severe rectal pain following bowel movements which is often accompanied by reflex anoxic seizures. Eventually there is a colour change down one half of the body; this may be horizontally from the waist down or involving one half of the body. Older patients are also affected by painful eye and jaw crises.

Credits

Medical text written November 2002 by Dr C Fertleman. Last updated February 2007 by Dr C Fertleman, Honorary Senior Lecturer, Royal Free and University College London Medical School, London, UK.

What are the symptoms?

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.

Birth episode
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.

Rectal episode
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.

Ocular crisis
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.

Mandibular/facial crisis
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.

How is it diagnosed?

Diagnosis is based on a careful history, a normal examination and normal EEG (electroencephalogram), ECG (electrocardiogram)and nerve conduction studies.

How is it treated?

In children, it has been important to manage the inevitable constipation that ensues from stool withholding secondary to fear of defecation. The episodes themselves respond to medication useful in the management of chronic neuropathic pain disorders - namely anticonvulsants. Carbamazepine is the most effective of these.

Inheritance patterns and prenatal diagnosis

Inheritance patterns
Autosomal dominant. Mutations in the sodium channel gene SCN9A cause paroxysmal extreme pain disorder in several families

Prenatal diagnosis
In a family where the mutation is known it is possible to offer prenatal diagnosis.

Is there support?

There is no support group for paroxysmal extreme pain disorder in the UK. Cross referrals to other entries in The Contact a Family Directory are intended to provide relevant support for those particular features of the disorder. Organisations identified in those entries do not provide support specifically for paroxysmal extreme pain disorder.

Families can use Contact a Family's freephone helpline for advice, information and, where possible, links to other families. Contact a Family's web-based linking service can be accessed at community.cafamily.org.uk

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