Corticobasal Syndrome and Corticobasal Degeneration Clinical Presentation

Updated: Dec 04, 2019
  • Author: Alexander Pantelyat, MD; Chief Editor: Selim R Benbadis, MD  more...
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Armstrong et al. describe the following clinical symptoms as part of the phenotypic spectrum of corticobasal degeneration (CBD): [1]

  • Insidious onset and gradual progression

  • Minimum duration of symptoms of at least 1 year

  • If corticobasal syndrome (CBS), asymmetric presentation of at least 2 of the following: (i) limb rigidity or akinesia, (ii) limb dystonia, (iii) limb myoclonus; PLUS 2 of either (i) orobuccal/limb apraxia (ii) cortical sensory deficit or (iii) alien limb phenomena more than levitation or parietal drift

  • Other phenotypes of CBD may present with

    • Executive dysfunction, behavioral and personality changes and visuospatial deficits, termed frontal behavioral-spatial syndrome  (FBS)

    • Effortful, agrammatical speech with speech apraxia and/or relatively preserved single word comprehension and impaired sentence/grammar comprehension, termed nonfluent/agrammatical variant of primary progressive aphasia (naPPA)

    • Axial or symmetric limb rigidity or akinesia, supranuclear gaze palsy or decreased vertical saccade velocity, postural instability or falls, behavioral changes, and/or urinary incontinence, termed progressive supranuclear palsy syndrome (PSPS)

    • Outside of the Armstrong et al. criteria, posterior cortical atrophy (PCA; typically presenting as visual dysfunction due to cortical involvement, with intact retinal and ocular function) has been associated with CBD pathology and this association is formalized in the 2017 PCA consensus classification [24]

  • The presence of prominent delusions or hallucinations (not related to levodopa) is more characteristic of diffuse Lewy body disease and makes a primary tauopathy such as CBD less likely



Motor abnormalities

The “classic” corticobasal syndrome (CBS) presentation includes levodopa-unresponsive asymmetric parkinsonism (rigidity and/or bradykinesia), limb dystonia and limb myoclonus. Rigidity is such cases may be secondary to parkinsonism (cogwheel type), dystonia, paratonia, or their combination.

  • Dystonia: most often involves the limbs (upper extremities), however can present as cervical dystonia or blepharospasm

  • Myoclonus: of cortical origin, most often seen in the limbs, and is often action related and stimulus sensitive (can be elicited by tapping the limb or testing reflexes). Short latency of myoclonus is more commonly seen (this can be confused with tremor), in contrast with classic cortical reflex myoclonus.

  • Hyperreflexia

Gait abnormalities

These are typically parkinsonian (reduced stride length and gait/turn speed, reduced/absent arm swing on the more affected side), and can involve gait freezing and lead to falls.

Cortical abnormalities

See the list below:

  • Apraxia: can involve limbs and other body parts. Limb apraxia typically presents as ideomotor apraxia, but limb-kinetic variants are also seen. Leg apraxia may make walking impossible. Orobuccal apraxia is also reported. Eyelid opening apraxia is frequently described; this may in fact represent blepharospasm of the pretarsal muscles rather than true apraxia.

  • Cortical sensory loss: detected by abnormalities in graphesthesia and stereognosis

  • Alien limb phenomena: semi-purposeful/unintended movements (simple or complex) that appear to interfere with normal tasks; can include dissociation from one’s own limb, intermanual conflict, enabling synkinesis, grasping, impulsive hand groping, magnetic apraxia, and purposeless wandering of the limb; simple levitation or parietal drift alone are not sufficient to be characterized as alien limb phenomena [1]

Cognitive abnormalities

These can include the following:

  • frontal-executive dysfunction (distractibility, perseveration, loss of judgment, motor planning deficit)

  • memory impairment (typically recent memory)

  • language (reduced verbal fluency, syntax and apraxia of speech)

  • visuospatial deficits

  • when the presentation is of posterior cortical atrophy (visuospatial) or Gerstmann syndrome, the underlying pathology is most likely to be Alzheimer disease rather than CBD

  • calculation difficulties (i.e. arithmetic for double and single digits) are observed early on in some patients with autopsy proven CBD, although this was reported in a single-center study [25]

Eye movement abnormalities

Pursuit eye movements are slow and saccadic with the appearance of several steps to reach a target, ipsilateral to the side with apraxia; [26] can involve abnormal saccades, horizontal gaze or vertical gaze (in the latter case would represent PSP phenotype of CBD).


See the list below:

  • Tremor: poorly characterized; can present as resting tremor (although not the typical 4–6 Hz frequency seen in Parkinson’s disease)

  • Autonomic dysfunction is generally not seen (however, may be a part of the PSP phenotype presenting as urinary incontinence)



The ultimate cause of corticobasal degeneration (CBD) is currently unknown, although symptoms are thought to be associated with progression of 4-repeat tau pathology and associated neuronal loss.

Case reports suggest that a familial predisposition may exist in some individuals with this disorder.

H1 tau haplotype homozygosity is associated with a predisposition to develop CBD and progressive supranuclear palsy (PSP). [13]

Rare mutations in the MAPT gene have been associated with CBD, as have C9orf72 repeat expansions and GRN (progranulin) mutations. [27, 12]


Physical Examination

A thorough neurological and cognitive assessment are required for a complete characterization of syndromes associated with CBD pathology (see Physical section above).  



Key complications in patients suffering from corticobasal degeneration (CBD) include:

  • Aspiration pneumonia in the setting of progressve dysphagia

  • Weight loss in the setting of progressive dysphagia (and potentially depression)

  • Sepsis due to complicated urinary tract infections in the setting of progressive neurogenic bladder dysfunction, or from wound infection in the setting of progressive loss of mobility

  • Loss of the ability to communicate due to progressive nonfluent aphasia coupled with motor and voice impairments limiting the choice of augmented/alternative communication devices

  • Loss of reading ability due to oculomotor difficulties and cortical visual impairment

  • Loss of the ability to socialize due to behavioral/personality changes

  • Injury due to falls in the setting of progressive imbalance (gait/limb apraxia may contribute to this)

  • Deconditioning due to reduced mobility and limited ability to exercise

  • Reactive depression with potential suicidality