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ATAXIA WITH INSIDIOUS ONSET (CHRONIC ATAXIAS)


Chronic ataxia with slow progression:-
The commonest causes of chronic slowly progressive ataxia are brain tumors (cerebellar astrocytoma-commonest) and hereditary ataxias (Friedreich's Ataxia and Ataxia Telangiectasia are the commonest).

Brain tumors -
They are always suspected in a previously healthy child who develops progressive ataxia with/ without headache. The commonest brain tumors causing ataxia are the infratentorial tumors seen commonly in children between 2 to 8 years. Supratentorial tumors may also cause ataxia when it involves the input fibers from the frontal lobes to the cerebellum.

1. Cerebellar astrocytoma -They are slow growing tumors consisting of a large cyst with a mural nodule in the region of the cerebellar hemisphere. Headache, signs of raised ICT and ataxia are the commonest features. The head may remain tilted to one side. (This is the earliest symptom to develop). Brain imaging is useful for diagnosis and treatment consists of surgical removal. Emergency shunting may be required with life threatening hydrocephalus.
   
   
2. Ependymoma of the fourth ventricle - It is derived from the cells that line the roof and floor of the 4th ventricle. Patients may develop raised ICT over months and may develop truncal ataxia. CT or MRI is useful in diagnosis and treatment consists of surgical removal along with radiation therapy.
   
   
3. Medulloblastoma - It is a primitive neuroectodermal tumor and presents either in the vermis or fourth ventricle. Patients present with rapidly evolving raised ICT and truncal ataxia due to rapid growth of the tumor. Treatment consists of surgical removal, radiation and chemotherapy.
   
   
4. Cerebellar Hemangioblastoma :- It is a neurocutaneous syndrome inherited in an autosomal dominant fashion and consists of hemangioblastomas of the cerebellum and retina (Retinal hemangioblastomas occur earlier), renal carcinoma and pheochromocytoma.

Hereditary Ataxias:-
Friedreich's ataxia - It is inherited as an autosomal recessive condition. The symptoms begin in the first decade of life as unsteady gait and rapid progression. Rhomberg's test is positive and patients have an impaired vibration & position sense. The deep tendon reflexes are absent showing involvement of posterior column and posterior roots. The patients have an extension planter reflex due to spasticity and involvement of the cortical tracts. Patients always develop dysarthria. Along with CNS involvement, the patients develop skeletal deformities in form of scoliosis and flexion contractures of the knees and pes cavus. Cardiomyopathy may also be seen. These patients have increased susceptibility to develop diabetes. EMG shows decrease conduction of sensory nerves. The patients are usually confined to the wheel chair by early twenties. Treatment is only symptomatic.

Ataxia Telangiectasia - It is an autosomal recessive neurocutaneous syndrome. Ataxia, predominantly truncal, starts early in childhood. Telangiectasias may be present at 2 years of age but become apparent at 4-6 years. They appear first on bulbar conjunctiva and then spread in a butterfly distribution on face, ears and neck, Mental development may slow over period of time. These children have recurrent sinopulmonary infection and serum IgA levels are decreased or absent. Thymus has an embryonic appearance and they also have an impaired cellular immunity. They have increase propensity to neoplasia due to generalized disorder of tissue differentiation and cellular repair. Elevated alpha fetoproteins (AFP) and carcinoembryonic antigens (CEO) are found commonly. Prognosis is poor.

Chronic ataxia with intermittent or stationary course:-
It is seen commonly in patients with chronic drug ingestion (antiepileptics), Hartnup's disease, Refsum's disease and congenital malformations (They are usually associated with mental retardation)

Hartnup's disease :-
It is an autosomal recessive metabolic error associated with massive aminoaciduria and nicotinamide deficiency. Tryptophan, instead of being converted to nicotinamide is converted to indole derivatives. Patients present with pellagra like itching eruptions on visible parts of the skin, ataxia, nystagmus, double vision and exaggerated deep tendon reflexes. Mental changes in form depression, confusion, hallucination may also be seen. Treatment is by giving large doses of oral nicotinamide along with high protein diet.