Question

Describe & explain & discuss diseases of the basal ganglia (Parkinson’s & Huntington’s)

Answer 1

APPLIED PHYSIOLOGY – DISORDERS OF BASAL GANGLIA
1. PARKINSON DISEASE
Parkinson disease is a slowly progressive degenerative disease of nervous system associated with destruction of brain cells, which produce dopamine. It is named after the discoverer James Parkinson. It is also called parkinsonism or paralysis agitans. Great boxer Mohammed Ali is affected by parkinsonism because of repeated blows he might have received on head resulting in damage of brain cells producing dopamine.
Causes of Parkinson Disease
Parkinson disease occurs due to lack of dopamine caused by damage of basal ganglia. It is mostly due to the destruction of substantia nigra and the nigrostriatal pathway, which has dopaminergic fibers. Damage of basal ganglia usually occurs because of the following causes:
i. Viral infection of brain like encephalitis ii. Cerebral arteriosclerosis
iii. Injury to basal ganglia
iv. Destruction or removal of dopamine in basal
ganglia. It occurs mostly due to long­term treat­ ment with antihypertensive drugs like reserpine. Parkinsonism due to the drugs is known as drug-induced parkinsonism.
v. Unknown causes: Parkinsonism can occur because of the destruction of basal ganglia due to some unknown causes. This type of parkin­ sonism is called idiopathic parkinsonism.
Signs and Symptoms of Parkinson Disease.
i.Tremor
ii. Slowness of movements
iii. Poverty of movements.
iv. Rigidity
v. Gait
vi. Speech problems
vii. Emotional changes.
Treatment for Parkinson Disease
As Parkinson disease is due to lack of dopamine caused by damage of dopaminergic fibers, it is treated by dopamine injection.

Huntington’s disease
This is an autosomal dominant inherited disorder, usually present- ing in adult life. It is due to expansion of a trinucleotide repeat on chromosome 4 and frequently demonstrates anticipation (younger age of onset in subsequent generations).
Clinical features: Gradually progressive chorea and behavioural disturbance are the earliest symptoms. There is cognitive impair- ment, which later becomes frank dementia. Seizures may occur late in the disease.
Investigations: The diagnosis is confirmed by genetic testing; pre- symptomatic testing for other family members is available but must be preceded by appropriate counselling. Brain imaging may show caudate atrophy but is not reliable.
Management: Chorea may respond to risperidone or tetrabenazine. Depression is common and may be helped by antidepressant medi- cation. Long-term psychological support and eventually institu- tional care are often needed.