Phocomelia is a congenital condition that involves malformations of human arms and legs which results in a flipper-like appendage. A prominent cause of phocomelia is the mother's use of the drug thalidomide during pregnancy; however, the causes of most cases are to be determined.
Occurrence in an individual results in various abnormalities to the face, limbs, ears, nose, vessels and many other underdevelopments. Although operations may improve some abnormalities, many are not surgically treatable due to the lack of nerves and other related structures.
The term is from Ancient Greek φώκη phōkē, "seal (animal)" + -o- interfix + μέλος melos, "limb" + English suffix -ia). Phocomelia is an extremely rare congenital disorder involving malformation of the limbs (dysmelia). Étienne Geoffroy Saint-Hilaire coined the term in 1836.
Signs and symptoms
The symptoms of phocomelia syndrome are undeveloped limbs and absent pelvic bones; however, various abnormalities can occur to the limbs and bones. Usually the upper limbs are not fully formed and sections of the "hands and arms may be missing". Short arm bones, fused fingers, and missing thumbs will often occur. Sometimes hands or fingers will be present but limp due to having no bones or being loosely attached. Legs and feet are also affected similarly to the arms and hands. Individuals with phocomelia will often lack thigh bones, and the hands or feet may be abnormally small or appear as stumps due to their close "attachment to the body".
According to National Organization for Rare Disorders (NORD), individuals carrying phocomelia syndrome will generally show symptoms of growth retardation previous to and after birth. The syndrome can also cause severe mental deficiencies in infants. Infants born with phocomelia will normally have a petite head with "sparse hair" that may appear "silvery-blonde". Hemangioma, the abnormal buildup of blood vessels, will possibly develop around the facial area at birth and the eyes may be set widely apart, a condition known as orbital hypertelorism. The pigment of the eyes will be a bluish white. Phocomelia can also cause: an undeveloped nose with slender nostrils, disfigured ears, irregularly petite jaws (a condition known as micrognathia), and a cleft lip with cleft palate. According to NORD, severe symptoms of phocomelia include: A fissure of the skull and a projecting brain known as encephalocele An accumulation of spinal fluid under the skull also known as hydrocephalus, causing vomiting and migraines An abnormally shaped uterus (bicornuate) Inability to clot blood efficiently due to a low amount of platelets running through the blood Malformations in the kidney and heart Shortened neck Abnormalities in the urethra
Thalidomide syndrome symptoms
When an individual is born with phocomelia due to drugs or pharmaceuticals, it is known as thalidomide syndrome. The symptoms of thalidomide syndrome are defined by absent or shortened limbs, causing flipper hands and feet. According to Anthony J Perri III and Sylvia Hsu they can additionally receive: Palsy disorder of the face Ear and eye abnormalities, resulting in limited/complete loss of hearing or sight Gastrointestinal and genitourinary tract disorders Ingrown genitalia Undeveloped/missing lungs Distorted digestive tract, heart, kidney Hypoplastic or absent bones
The infants that were exposed to thalidomide during development phases had a 40% chance of survival. The McMredie–McBride hypothesis explains that the limbs of the infants become malformed as a result of the thalidomide harming the neural tissue—simply because the neural tissue has such a large impact on formation and development of the limbs.
Causes
Thalidomide
Thalidomide was released onto the market in 1958 in West Germany under the name Contergan. Primarily prescribed as a sedative or hypnotic, thalidomide also claimed to cure "anxiety, insomnia, gastritis, and tension". Afterwards it was used against nausea and to alleviate morning sickness in pregnant women. Thalidomide became an over-the-counter drug in Germany around 1960, i.e. it could be bought without a prescription. Shortly after the drug was sold, in Germany between 5,000 and 7,000 infants were born with phocomelia. Only 40% of these children survived.