Signs and symptoms
The most common signs leading to the diagnosis of Noonan syndrome are unique facial characteristics and musculoskeletal features. The facial characteristics are most prominent in infancy, becoming less apparent with age in many people with Noonan syndrome. Head
Some of the characteristic features of Noonan syndrome include a large head with excess skin on the back of the neck, low hairline at the nape of the neck, high hairline at the front of the head, triangular face shape, broad forehead, and a short, webbed neck. In the eyes, hypertelorism (widely set eyes) is a defining characteristic, present in 95% of people with Noonan syndrome. This may be accompanied by epicanthal folds (extra fold of skin at the inner corner of the eye), ptosis (drooping of the eyelids), proptosis (bulging eyes), strabismus (inward or outward turning of the eyes), nystagmus (jerking movement of the eyes) and refractive visual errors. The nose may be small, wide, and upturned. The development of the ears and auditory system may be affected in people with Noonans syndrome. This can result in low-set ears (in over 90%), backward-rotated ears (over 90%), thick helix (outer rim) of ear (over 90%), incomplete folding of ears, chronic otitis media (ear infections), and hearing loss. Development of the mouth may also be affected in Noonan syndrome. This can result in deeply grooved philtrum (top lip line) (over 90%), micrognathia (undersized lower jaw), high arched palate, articulation difficulties (teeth dont line up) which can lead to dental problems.
History
AMAN, also known as Chinese Paralytic Syndrome, was first described by a group of Johns Hopkins University and University of Pennsylvania neurologists in collaboration with neurologists from the Second Teaching Hospital of Hebei Medical School and Beijing Childrens Hospital. In 1991, Guy Mckhann, Jack Griffin, Dave Cornblath and Tony Ho from Johns Hopkins University and Arthur Asbury from University of Pennsylvania visited China to study a mysterious epidemic of paralytic syndrome occurring in northern China. Every summer, hundreds of children from rural China developed acute paralysis and respiratory failure. Hospitals were overwhelmed with number of cases and often ran out of ventilators and hospital beds. Examination of these children showed that many of them had acute flaccid paralysis and areflexia but with little or no sensory loss. Electrophysiological testing of these children showed motor axonal loss with occasional conduction block with a lack of demyelinating features and normal sensory potentials. In contrast, the common form of Guillain–Barré syndrome in the West often presents with sensory loss and demyelination on electrophysiology testing and is more common in adults. Later, several autopsies confirmed the focus of the immune attack was at the motor axolemma especially around the nodes of Ranvier. These cases showed deposition of antibody and complement along the motor axolemma and associated macrophage infiltration. References


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