Cortico Basal Degeneration (CBD)
Like PSP, Cortico Basal Degeneration (CBD) is a neuro-degenerative disease that causes disturbances of movement and behaviour. It is an older person’s disease, with average age of onset at 63 years. Progressive ‘numbness or deadness’ or loss of use of one hand is a common symptom, and a stroke or brain tumour may be initially suspected. Other early symptoms include jerking of the fingers, slowness and awkwardness for dextrous acts and an ‘alien limb’ (the inability to recognise as one’s own the affected limb). There is a slow but relentless progression of the disorder to involve firstly the side with the alien limb, and then the other arm and leg. There may be disturbances of eye movements, although it is uncommon to see the severe gaze paralysis that is characteristic of classical PSP.
Dr Huw Morris, a Research Fellow sponsored by The PSP Association, writes about CBD below:-
"Cortico Basal Degeneration (CBD) is probably the most closely related disease to PSP and some doctors argue that they are variants of the same condition. Like PSP, CBD attacks areas in the base of the brain which control eye movement and balance, and complaints of difficulty with vision and of falls are common in the early stages of both conditions.
Unlike PSP, CBD also affects areas of the brain which control 'higher function' related to movement and sensation, usually asymmetrically. Patients with CBD commonly complain of difficulty in controlling or using one hand, although the strength and sensation in the hand are normal. This appears to result from breakdown of the semi automatic 'motor routines' that we use in everyday life to put many complex individual muscle movements together into a highly skilled movement, like writing or tying up a shoelace.
Damage in closely related parts of the brain can cause irregular muscle jerking called 'myoclonus' or, very occasionally, the loss of control of the hand can appear to make the hand have a mind of its own. Similar phenomena can occur in the legs.
The type of nerve cell damage in the brain is very similar, and the type of abnormal 'tau' protein laid down is identical to that seen in PSP. Not all patients with CBD have these very typical featues outlined above and, similarly, patients with PSP can often have some of the CBD type features in mild form. Studies of the process of making diagnoses by expert neurologists indicated that PSP and CBD are the conditions which are most likely to be confused. Working out the relationship between CBD and PSP is very important in investigating the disease process, and this work is very much advanced by examining the brain tissue of patients after death. This wil improve the knowledge and treatments available for future generations and will help resolve the types of symptoms and nerve cell damage seen in these conditions".
Bibliography - CBD
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Frisoni, G, Pizzolato, G, Zanetti, O et al Corticobasal degeneration: neuropsychological assessment and dopamine D2 receptor SPECT analysis. Eur. Neurol., 1995; 35(1): 50-4
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Ikeda, K, Akiyama, H ,Iritani, S et al Corticobasal degeneration with primary progressive aphasia and accentuated cortical lesion in superior temporal gyrus: case report and review. Acta Neuropathologica, 1996; 92(5): 534-9
Jendroska, K, Rossor, M, Mathias, C Morphological overlap between corticobasal degeneration and Pick’s disease: a clinicopathological report. Movement Disorders, 1995; 10(1): 111-4.
Leiguarda, R, Less, A, Merello, M et al The nature of apraxia in corticobasal degeneration. Journal of Neurology, Neurosurgery and Psychiatry, 1994; 57(4):455-9
