NEUROLOGY. BRIEF REVIEW

Parkinson’s disease	Degenerative disorder of CNS associated with Lewis bodies and depigmentation of the substantia nigra pars compacta. Tremor at rest, pill-rolling tremor, cogwheel rigidity, akinesia, and postural instability.
Hemibalismus	Sudden, wild flailing of one arm (sometime one leg). Characterized by Subthalamic nucleus lesion. Loss of inhibition of thalamus through globus pallidus.
Huntington’s disease	Autosomal dominant trinucleotide (CAG) repeats disorder. Chorea, aggression, depression, and dementia. Atrophy of striatal nuclei (main inhibitor of movement). Caudate loses ACh and GABA.
Chorea	Sudden, jerky, purposeless movement. Basal ganglia lesion e.g. Huntington’s disease.
Athetosis	Slow, writing movements, especially of fingers. Basal ganglia lesion.
Myoclonus	Sudden, brief muscle contraction. Jerks, hiccups.
Dystonia	Sustained, involuntary muscle contractions. Writer’s cramps.

 First aid for USMLE Step 1. 2011.