Corticobasal syndrome (CBS) is a rare,

progressive Progressive may refer to: Politics * Progressivism, a political philosophy in support of social reform ** Progressivism in the United States, the political philosophy in the American context * Progressive realism, an American foreign policy par ...

atypical Parkinsonism syndrome and is a tauopathy related to

frontotemporal dementia Frontotemporal dementia (FTD), or frontotemporal degeneration disease, or frontotemporal neurocognitive disorder, encompasses several types of dementia involving the progressive degeneration of frontal and temporal lobes. FTDs broadly present as ...

. CBS is typically caused by the deposit of tau proteins forming in different areas of the brain.

Classification

CBS is the most common type of

corticobasal degeneration Corticobasal degeneration (CBD) is a rare neurodegenerative disease involving the cerebral cortex and the basal ganglia. CBD symptoms typically begin in people from 50 to 70 years of age, and the average disease duration is six years. It is chara ...

(CBD) although the terms CBD and CBS have been used interchangeably in the past. The other three phenotypes of CBD are: * frontal-behavioral dysexecutive-spatial syndrome (FBS) * nonfluent/agrammatic variant of primary progressive aphasia (naPPA), and * progressive supranuclear palsy syndrome (PSPS).

Symptoms and signs

Symptoms of CBS include apraxia, alien limb phenomenon, frontal deficits, and extrapyramidal motor symptoms such as myoclonus or rigidity. Movement deficits often begin on one side and progress to the other.

Pathophysiology

CBD is the pathology underlying approximately 50% of CBS cases.

Diagnosis

The Armstrong criteria were proposed in 2013; the accuracy of these is limited and further research is needed. Symptoms may be symmetric or asymmetric, with one or more of the following: # limb rigidity or akinesia # limb dystonia # limb myoclonus, plus one of: # orobuccal or limb apraxia # cortical sensory deficit # alien limb phenomena (more than simple levitation) The onset is insidious with gradual progression, lasting one year or more, with no

exclusion criteria In a clinical trial, the investigators must specify inclusion and exclusion criteria for participation in the study. Inclusion and exclusion criteria define the characteristics that prospective subjects must have if they are to be included in a st ...

present. The diagnosis is more likely if onset is after age 50, there is no family history (2 or more relatives), and there is no genetic mutation affecting T (e.g., MAPT). Probably sporadic CBS is more likely if there are two of: # limb rigidity or akinesia # limb dystonia # limb myoclonus * plus two of: # orobuccal or limb apraxia, # cortical sensory deficit # alien limb phenomena (more than simple levitation) The diagnosis is excluded if there is evidence of: * Lewy body disease *

multiple system atrophy Multiple system atrophy (MSA) is a rare neurodegenerative disorder characterized by autonomic dysfunction, tremors, slow movement, muscle rigidity, and postural instability (collectively known as parkinsonism) and ataxia. This is caused by progr ...

Alzheimer's disease Alzheimer's disease (AD) is a neurodegeneration, neurodegenerative disease that usually starts slowly and progressively worsens. It is the cause of 60–70% of cases of dementia. The most common early symptom is difficulty in short-term me ...

amyotrophic lateral sclerosis Amyotrophic lateral sclerosis (ALS), also known as motor neuron disease (MND) or Lou Gehrig's disease, is a neurodegenerative disease that results in the progressive loss of motor neurons that control voluntary muscles. ALS is the most comm ...

* semantic or logopenic variant primary progressive aphasia * structural lesion suggestive of focal cause * granulin mutation or reduced plasma progranulin levels * TDP-43 or fused in sarcoma (FUS) mutations The diagnostic criteria for clinical use may result in a misdiagnosis of other tau-based diseases. The ''probable'' criteria are proposed for clinical research.

Differential

Other degenerative pathologies that can cause corticobasal syndrome include: *

Pick's disease Frontotemporal dementia (FTD), or frontotemporal degeneration disease, or frontotemporal neurocognitive disorder, encompasses several types of dementia involving the progressive degeneration of frontal and temporal lobes. FTDs broadly present as ...

with Pick bodies *

Lewy body dementia Lewy body dementias are two similar and common subtypes of dementia—dementia with Lewy bodies (DLB) and Parkinson's disease dementia (PDD). Both are characterized by changes in thinking, movement, behavior, and mood. The two conditions have sim ...

s * Neurofilament inclusion body disease * Creutzfeldt-Jakob disease * Frontotemporal degeneration due to

progranulin Granulin is a protein that in humans is encoded by the ''GRN'' gene. Each granulin protein is cleaved from the precursor progranulin, a 593 amino-acid-long and 68.5 kDa protein. While the function of progranulin and granulin have yet to be deter ...

gene mutation * Motor neuron disease‐inclusion dementia. The symptoms of classic CBS differ from CBD in that CBD also includes cognitive deficits in the

executive functions In cognitive science and neuropsychology, executive functions (collectively referred to as executive function and cognitive control) are a set of cognitive processes that are necessary for the cognitive control of behavior: selecting and succe ...

Prognosis

The average survival time after disease onset is estimated at 6.5  years.

References

{{reflist Cognitive disorders Neurodegenerative disorders Rare syndromes