Corticobasal Degeneration

Corticobasal ganglionic degeneration present with asymmetric basal ganglia (akinesia, rigidity, dystonia) and cerebral cortical (apraxia, cortical sensory loss, alien limb) manifestations. We see the alien limb with parietal lobe, medial frontal lobe, and corpus callosum pathology. Dementia is a variable but may be the presenting symptom. 

Oculomotor involvement like that in progressive supranuclear palsy may occur. But the major difference between PSP and corticobasal degeneration is that the latter is with limb coordination problems, and the former is with balance and walking problems. 

Prognosis

Survival ranges from 2.5 to 12 years, with a median of about 8 years. 

Neuropathology

Corticobasal degeneration pathology shows abundant ballooned, achromatic neurons, and focal cortical atrophy predominating in medial frontal and parietal lobes, plus degeneration of the substantia nigra. We also see astrocytic plaques in the cortex. corticobasal degeneration: neuronal tau pathology shows wispy, fine-threaded tau incus. Magnetic resonance imaging may show asymmetric atrophy in the frontal and parietal lobes contralateral to the dominantly affected limbs. 

Treatment

We have limited treatment options for corticobasal degeneration, with only a minority of patients responding to L-dopa preparations given for parkinsonism. Myoclonus may respond to benzodiazepines, particularly clonazepam. No specific treatment for dementia is available, but it may not be cholinergic, suggesting that cholinesterase inhibitors are of limited value. Depression is common in corticobasal degeneration, but few data exist on treatment response. 

Clinical Manual of Neuropsychiatry, 2017