Congenital and inherited diseases Medical Assignment Help

CEREBRAL PALSY

This term describes disorders apparent at birth or in childhood due to brain damage in the neonatal period leading to non-progressive deficits.
Mental retardation, varying from severe intellectual impairment to mild learning disorders, is common in all forms of cerebral palsy, but severe physical disability is not necessarily associated with a severe defect in higher erebral function.

CAUSES

The precise cause of brain damage in an individual child may be difficult to determine. The following may be responsible:
HYPOXIA in utero and/or during parturition TRAUMA, during parturition or in the neonatal period PROLONGED CONVULSIONS OR COMA (e.g. febrile convulsions, hypoglycaemia) in infancy

Infantile hemiparesis
Hemiparesis may be noted at birth or during childhood. Hemiatrophy of the limbs (and atrophy of the contralateral  emisphere) is usual. Seizures are common.

Congenital ataxia
This is incoordination and hypotonia of the trunk and limbs.
DYSRAPHISM
Failure of normal fusion of the fetal neural tube leads to this group of congenital anomalies.

Anencephaly

Anencephaly is absence of the brain and cranial vault, and is incompatible with life. Meningo-encephalocele This is an extrusion of brain and meninges through a midline skull defect that varies from a minor protrusion to a massive defect.
Spina bifida
In spina bifida there is failure of fusion of the neural tube, usually in the lumbosacral region. Several varieties occur. SPINA BIFIDA OCCULTA. This is failure of fusion of the vertebral arch only. There are rarely neurological abnormalities and a bony anomaly is seen on X-ray. It occurs in 3% of the population. A dimple or a tuft of hair may overlie the lesion.
MENINGOMYELOCELE AND MYELOCELEWITH SPINA BIFIDA. Meningomyelocele consists of elements of the cord and lumbosacral roots contained within a meningeal sac that herniates through a defect in the vertebrae. In severe cases the lower limbs and sphincters are paralysed. The defect is visible at birth.Meningocele is a meningeal defect alone.  Hydrocephalus is commonly associated with theseabnormalities  Meningitis may follow if a sinus connects the s pinal canal with the overlying skin.

BASILAR IMPRESSION OF THE SKULL (PLATYBASIA) This is usually a congenital anomaly in which there is invagination of the foramen magnum and skull base upwards. The lower cranial nerves, medulla, upper cervical cord and roots are affected. It is often complicatedby the Arnold-Chiari malformation, in which aberrant cerebellar tissue extends through the foramen magnum. The condition also occurs in Paget’s disease and rarely in osteomalacia.

NEUROECTODERMAL SYNDROMES

These are disorders in which organs derived from ectoderm show a tendency to form tumours and hamartomas, with lesions in the skin, eye and nervous system. Neurofibromatosis (von Recklinghausen’s disease)
This is characterized by multiple skin neurofibromas and pigmentation. The neurofibromas arise from the neurilemmal sheath. One new case occurs in every 3000 live births. The mode of inheritance is autosomal dominant.

CLINICAL FEATURES (see p. 1025)

Clinically neurofibromatosis can be divided into type 1 (or peripheral) and type 2 (bilateral acoustic or central). The predisposing gene for type 1 has been localized to chromosome 17 and for type 2 to the long arm of chromosome 22. The main application for these genetic markerswill be for antenatal diagnosis and genetic counselling,  although the severity of the disease itself will not be predictable.

Skin tumours

Subcutaneous, soft, sometimes pedunculated, tumours appear. They may be multiple. Skin pigmentation Multiple caje-au-lait patches-pale brown macules 1- 20 em in diameter-are found. These are common in
the normal population, but more than five patches is abnormal.

TREATMENT

Surgery may be necessary for cosmetic reasons. Tumours causing pressure within the nervous system require excision, if this is feasible.
Tuberose sclerosis (epiloia) This is a rare autosomal dominant condition whose principal features are adenoma sebaceum, epilepsy and mental retardation (often severe). Adenoma sebaceum These are reddish nodules (angiofibromas) that develop on the cheeks in childhood. Other lesions Other lesions include shagreen patches, amelanotic naevi, retinal phakomas (glial masses), renal tumours, glial overgrowth in brain and gliomas. Cardiac rhabdomyomas, hamartomas of lung and kidney, and polycystic kidneys may also occur. Sturge-Weber syndrome (encephalofacial angiomatosis) There is an extensive port-wine naevus on one side of the face (usually in the distribution of a division of the fifth nerve) and a leptomeningeal angioma.Epilepsy is common. Familial occurrence is exceptional.  Von Hippel-Lindau syndrome (retinocerebellar angiomatosis)This is the occurrence in families (dominant inheritance  with variable penetrance) of retinal and cerebellar haem angioblastomas or, less commonly, aemangioblastomas
of the cord and cerebrum. Renal, adrenal and pancreatic cysts (and haemangioblastomas) may also be found. Polycythaemia sometimes occurs. There are numerous other disorders related to these conditions,for example ataxia telangiectasia and Osler-Web er-Rendu syndrome.

SPINOCEREBELLAR DEGENERATIONS

The classification of this large group of rare inherited disorders is complex. Three conditions will be mentioned here.

Hereditary spastic paraparesis Isolated progressive paraparesis runs in some families. The inheritance is variable. Additional features includingcerebellar signs, pes cavus, wasted hands and optic atrophy are somet  mes seen. The conditions are usually mild and progress slowly over many years. Ataxia telangiectasia (see p. 147) This is a rare, autosomal recessive condition that produces a progressive ataxic syndrome in childhood and early adult life.
There is striking telangiectasia of the conjunctiva, nose, ears and skin creases. There are also defects in cellmediated immunity and antibody production. A defect in DNA repair has been demonstrated. Death is usual by the third decade, either from infection or from the development
of lymphoreticular malignancy. PERONEAL MUSCULAR ATROPHY AND OTHER INHERITED NEUROPATHIES These disorders are classified within a large and complex group-the hereditary motor and sensory neuropathies (HMSN).
Peroneal muscular atrophy Peroneal muscular atrophy (Charcot-Marie-Tooth disease) is a common clinical syndrome in which there isdistal limb wasting and weakness that slowly progresses  over many years, mostly in the legs, with variable loss of sensation and reflexes. In advanced cases the distal wasting below the knees is so marked that the legs resemble ‘inverted champagne bottles’. Mild cases have only pes cavus and clawing of the toes and may pass unnoticed. Three forms are recognized:

1 HMSN type I-a demyelinating neuropathy
2 HMSN type II-an axonal neuropathy
3 Distal spinal muscular atrophy
Both autosomal dominant and recessive inheritance is seen in different families. In HMSN type I with dominant inheritance (the commonest form), linkage has been demonstrated for the locus on the long arm of chromosome
1.Optic atrophy, deafness, retinitis pigmentosa and spastic paraparesis are sometimes seen in variants of theseconditions. HMSN type III This was formerly known as the ‘hypertrophic neuropathy of Dejerine-Sottas’. It is an autosomal recessive demyelinating sensory neuropathy of childhood leading to severe incapacity during adolescence. It is notable because the CSF protein may be greatly elevated to g litre-lor more, and the CSF pathways are obstructed by greatly hypertrophied nerve roots.

Posted by: brianna

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