Cortical-basal ganglionic degeneration (CBGD), or corticobasal degeneration typically begins from 50 – 70 years of age. Mean survival is about 8 years. Its distinctive features are an asymmetric levodopa-resistant akinetic-rigid syndrome associated with "cortical" features such as apraxia, cortical sensory loss, and alien limb phenomenon. General cognitive function had been thought to be preserved.

This "classical" description emphasizing a parietal/perceptual-motor presentation may be biased because the cases mainly originate from movement disorder centers. Features of speech disturbances or dementia had been thought to represent the minority of cases. In a recent review by Grimes et al. only 4 of 13 pathologically proven patients had a prior clinical diagnosis of CBGD. It appears now that dementia can be a prominent feature of advanced disease and may be the most common feature. Aphasia can be seen in over 50% of patients. Depression is common. Apathy, social withdrawal, bizarre behavior, hypersexuality irritability, and anarthria have been described.

Parkinsonian signs including unilateral limb rigidity (79%), bradykinesia (71%), postural instability (45%) and apraxia are found in almost all patients. Dystonic posturing of the arm and hand is common (43%). Tremor when present is typically an action tremor that improves at rest. It frequently has a myoclonic (jerky) component. Stimulus sensitive myoclonus can be seen. The rigidity may be extreme and associated pain is common.

With progression cortical sensory deficits, pyramidal tract dysfunction, dysarthria, dysphagia and other symptoms emerge or worsen. Alien limb phenomena develop in 50% of cases. It may be as simple as levitation of a limb. Magnetic apraxia (approach behavior with groping and manipulation) is a sign of CBGD. Described eye movement abnormalities include saccadic pursuit, difficulty initiating saccades, and rarely supranuclear palsy.

CBGD, like PSP is a disorder of the tau protein (a tauopathy). It seems now that it has significant overlap with the frontotemporal dementias (FTD), parkinsonism associated with chromosome 17 (FTDP-17), primary progressive aphasia (PPA), Pick's disease, and PSP.

General References On Clinical Features of Parkinsonisms
 

*Handbook of Clinical Neurology Vol 49 Extrapyramidal disorders: Vinken, Bruyn, Klawans eds.   Elsevier Science publishers 1996

Movement Disorders a Comprehensive Survey;: Weiner, Lang A. eds. Futura publishing company 1989

Neurodegenerative Diseases, Calne, D., eds. W.B. Saunders Company 1994

Parkinson's Disease and Movement Disorders, Jankovic, Tolosa ,eds. Urban & Scharzenberg 1988

References for criteria in the diagnosis of Parkinsonism

CBGD

D. A. Grimes, A. E. Lang MD, FRCPC, C. B. Bergeron Dementia as the most common presentation of cortical-basal ganglionic degeneration Neurology Volume 53  Number 9  December 10, 1999