Huntington's disease is a progressive neurodegenerative disorder characterized by loss of neurons in the caudate nucleus and putamen.
Huntington's disease is an autosomal dominant disorder caused by CAG triplet repeat expansion in the Huntingtin gene (found on chromosome 4). Symptoms usually begin to appear in middle age (30-50 years), and both sexes are affected equally. Symptoms include progressive choreiform movements of all limbs, ataxic gait, dementia, depression, and grimacing. The mutation in Huntington's disease lead to atrophy of the caudate nucleus and putamen, with neuronal loss and gliosis.
Alexi et al. discuss the pathological findings of Huntington's. The Vonsattel scale is used to grade the severity of Huntington's disease at autopsy. The scale ranges from grade 0, which shows little-to-no loss of neurons in the striatum, to grade 4, which shows up to 95% neuronal loss. The Vonsattel grade at autopsy correlates well with symptoms prior to death.
Van den Bogaard et al. examined the neuroanatomy of Huntington's patients with active disease versus controls who were genetically positive but not symptomatic and also versus normal controls. Using functional MRI, the authors found that in active Huntington's patients there is a loss of brain volume in the putamen, caudate, and accumbens nucleus. They also found that in the inactive but predestined patients there is lesser loss of volume in these areas versus normal controls.
Figure A is an MRI image showing the shrunken caudate nucleus and enlarged ventricles of a patient affected by Huntington's disease.
Answer 1: Loss of neurons in the substantia nigra pars compacta is associated with Parkinson's disease.
Answer 2: Alpha-synuclein intracellular inclusions (“Lewy bodies”) are seen in Parkinson's disease and in Lewy body dementia.
Answer 4: Lipohyalinosis is seen in lacunar stroke. Hemiballismus or other movement disorders may result from lacunar stroke.
Answer 5: Beta-amyloid plaques are classically seen in Alzheimer's dementia.
Alexi T1, Borlongan CV, Faull RL, Williams CE, Clark RG, Gluckman PD, Hughes PE. Neuroprotective strategies for basal ganglia degeneration: Parkinson's and Huntington's diseases. Prog Neurobiol. 2000 Apr;60(5):409-70.
PMID:10697073 (Link to Abstract)
van den Bogaard SJ1, Dumas EM, Ferrarini L, Milles J, van Buchem MA, van der Grond J, Roos RA. Shape analysis of subcortical nuclei in Huntington's disease, global versus local atrophy--results from the TRACK-HD study. J Neurol Sci. 2011 Aug 15;307(1-2):60-8. doi: 10.1016/j.jns.2011.05.015. Epub 2011 May 31.
PMID:21624624 (Link to Abstract)