Pallister–Hall syndrome (abbreviated PHS) is a disorder that affects the development of many parts of the body. It is named for Judith Hall and Philip Pallister. Presentation
Most people with this condition have extra fingers and/or toes (polydactyly), and the skin between some fingers or toes may be fused  (cutaneous syndactyly). An abnormal growth in the brain called a hypothalamic hamartoma is characteristic of this disorder. In many cases, these growths do not cause any medical problems; however, some hypothalamic hamartomas lead to seizures or hormone abnormalities that can be life-threatening in infancy. Other features of Pallister–Hall syndrome include a malformation of the airway called a bifid epiglottis, laryngeal cleft, an obstruction of the anal opening (imperforate anus), and kidney abnormalities. Although the signs and symptoms of this disorder vary from mild to severe, only a small percentage of affected people have serious complications. Seizures
As noted above, the hypothalamic hamartoma can cause seizures. The most common types of seizures that occur are known as gelastic epilepsy. The term gelastic originates from the Greek word "gelos which means "laughter". Seizures may begin at any age but usually before three or four years of age. The seizures usually start with laughter and the laughter is often described as being "hollow" or "empty" and not very pleasant. The laughter occurs suddenly, comes on for no obvious reason and is usually completely out of place.
Pre-excitation syndrome is a heart condition in which part of the cardiac ventricles are activated too early. Pre-excitation is caused by an abnormal electrical connection or accessory pathway between or within the cardiac chambers. Pre-excitation may not cause any symptoms but may lead to palpitations caused by abnormal heart rhythms. It is usually diagnosed using an electrocardiogram, but may only be found during an electrophysiological study. The condition may not require any treatment at all, but symptoms can be controlled using medication or catheter ablation. Types
Several types of pre-excitation syndrome have been described. Pathophysiology
Normally, the atria and the ventricles are electrically isolated, and electrical contact between them exists only at the "atrioventricular node". In all pre-excitation syndromes, at least one more conductive pathway is present. Physiologically, the normal electrical depolarization wave is delayed at the atrioventricular node to allow the atria to contract before the ventricles. However, there is no such delay in the abnormal pathway, so the electrical stimulus passes to the ventricle by this tract faster than via normal atrioventricular/bundle of His system, and the ventricles are depolarized (excited) before (pre-) normal conduction system. References


== External links ==