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| Year : 1999 | Volume
: 47
| Issue : 4 | Page : 340-1 |
Juvenile Huntington's disease.
Srivastava T, Lal V, Prabhakar S
How to cite this article:
Srivastava T, Lal V, Prabhakar S. Juvenile Huntington's disease. Neurol India 1999;47:340 |
Huntington's disease is an autosomal dominant disorder, that usually begins in mid life and is characterised by involuntary movements, psychological changes and dementia. In large studies, the mean age of onset is 35-42 years. 10% cases of Huntington's disease develop it before age of 20 years and only 3% cases the disease develops before the age of 15. These patients typically have features of parkinsonism and experience a more rapid clinical decline compared to adult onset illness.
A 20 year girl was in good health till the age of 12 years when she developed poor school performance and started forgetting whatever she had read few days back. After 5 year of onset of these symptoms, she lost interest in family members and her friends. 6 months prior to admission she developed slowness of gait and initiation and performance of routine work along with fine tremors all over the body. Patient had no choreiform movements. All symptoms were gradual in onset and slowly progressive in nature. She had strong family history suggestive of Huntington's disease. Her father, grandmother, grandmother's sister and brother had adult onset choreoathetoid movements and dementia, and succumbed to their illness after a variable period. On examination she had an expressionless face. Higher mental examination disclosed impaired attention span, calculation, judgement and intelligence. She had a slow and monotonous speech with diminished word output. Cogwheel rigidity was present in all four limbs with flexor planters. Glabellar tap, snout and pout reflexes were positive. Eye movements were also affected. Pursuit was slow and saccades was absent. There was restriction of upward gaze. Patient had resting and action tremors. Investigation including haemogram, ESR, peripheral blood film, hepatic and renal function tests were normal. Ophthalmic examination did not show Kayser Fleischer ring. CT scan head showed atrophy of caudate nucleus with prominence of frontal horn of lateral ventricle [Figure. 1]. On the basis of clinical feature, strong family history and CT findings she was diagnosed as a case of juvenile Huntington's disease.
The term Huntington's disease is used to include patients with choreiform movements, dementia and other neuropsychiatric manifestations. The diagnosis is difficult or even nearly impossible if the principle diagnostic criteria viz. the presence of hereditary chorea among family members is not applied. The term juvenile Huntington's disease is used to include patients with definite signs and symptoms appearing before 20 year of age. The prevalence in adults is around 7 to 10 per 100,000 population. Population surveys have shown the incidence of juvenile Huntington's disease to be between 1% to 9.6% in different groups. In the New England study of 243 cases, 25 cases had onset of Huntington's disease before the age of 19 years.[1] Pani et al described a case of juvenile Huntington's disease manifesting at the age of seven years with predominant choreiform movements.[2]
90% of juvenile patients inherit the Huntington's disease gene from affected father rather than affected mother. There is female sex preponderance among juvenile cases with estimated ratio of between 1.5 : 1 to 2.0:1. Dementia is much more marked in juvenile form. Juvenile cases develop the hypokinetic rigid variant far more frequently than adults. One third to one half of the juvenile cases, shows the primary or secondary Westphal type i.e. they either starts with hypertonia, rigidity and loss of facial expression or gradually proceed from choreiform movements to picture of generalized rigidity with cogwheeling. Impairment of ocular motility, an early sign of Huntington's disease, which is characterized by progressive slowing of saccadic initiation and range, fixation and vengeance abnormalities is more prominent in juvenile onset patients.[3] In addition, signs and symptoms of pyramidal involvement, tremors and cerebellar signs may be detected in some patients. In juvenile Huntington's disease seizure disorders are observed occasionally, which presumably reflect extensive and rapid neuronal degeneration. The present case, a 12 year girl, with inheritance from father, had feature of hypokinetic rigid form with ocular abnormalities, tremor and hypereflexia. CT scan showed atrophy of caudate nucleus with prominence of frontal horn of lateral ventricle.
Molecular genetic investigations have far advanced in recent years and have localized a genetic marker on G-8 locus of chromosome 4.[4] For diagnosis of Huntington's disease, trinucleotide repeat sequence using polymerize chain reaction test is gold standard. The sensitivity of diagnosis based on radiological examination is only 87.5%.[5] Levodopa is useful when rigidity is the main feature of Huntington's disease.
| 1. | Martin JB, Gusella JF : Huntington's disease-pathogenesis and management. N Engl J Med 1986; 315 : 1267-1275.  |
| 2. | Pani C, Rajadhyaksha SB, Varudkar BL et al : Juvenile Huntington's disease. Neurol India 1993; 41 : 224-226. |
| 3. | Collewijn H, Went LN, Tamminga ED : Oculomotor defects in patients with Huntington's disease and their off springs. J Neurol Sci 1988; 86 : 307-320. |
| 4. | Martin JB : Huntington's disease : New approaches to a old problem. Neurology (NY) 1984; 34 : 1059-1072. |
| 5. | Sharma P, Savy L, Britton J : Huntington's disease a molecular genetic and CT Comparison. J Neurol Neurosurg Psychiatry 1996; 60 : 206-208. |
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