Corticobasal Degeneration (CBD)

Corticobasal Degeneration (CBD) is the rarest of the four atypical parkinsonism disorders. Depending on whom you ask, it’s classified as an atypical parkinsonism disorder, a non-Alzheimer’s dementia, or a type of frontotemporal degeneration. CBD is most closely similar to PSP in terms of symptoms and pathology. Many organizations that perform research on PSP also research CBD.

CBD Symptoms

Because CBD is so rare, research has been very limited. Most studies of autopsy-confirmed disease only include a few dozen cases. It’s hard to be definitive with such small numbers.

The medical community now uses the term CBS or corticobasal syndrome to refer to a clinical diagnosis. CBD or corticobasal degeneration is now used for an autopsy-confirmed diagnosis.

Since 2013, CBD experts refer to four main types of CBD:

  • Corticobasal syndrome: limb rigidity; limb akinesia (lack of movement); limb dystonia; myoclonus (jerky movements); limb apraxia (difficulty using a limb not due to motor of sensory problems); orobuccal (mouth and cheek) apraxia; cortical sensory deficit (inability to discern a sensation); alien limb phenomena (the limb seems to have a mind of its own). We could describe this type as “classic CBD.”
  • Frontal behavioral-spatial syndrome: executive dysfunction; behavioral or personality changes; visuospatial deficits. This type may look like the behavioral variant of frontotemporal dementia.
  • Nonfluent/agrammatic variant of primary progressive aphasia: effortful, agrammatic speech; impaired grammar/sentence comprehension; apraxia of speech (groping, distorted speech production). This type may look like a type of frontotemporal degeneration called primary progressive aphasia (PPA).
  • Progressive supranuclear palsy syndrome: axial rigidity; limb rigidity; akinesia; postural instability or falls; urinary incontinence; behavioral changes; supranuclear vertical gaze palsy; decreased velocity of vertical saccades. This type looks like PSP.

The symptoms of these four types are so different that they seem to be entirely different disorders.

CBD Treatments

There is remarkably limited treatment for CBD/CBS. The most effective treatments are the therapies: physical therapy, occupational therapy, and speech therapy. Therapies are pinpointed on prevention of falls and aspiration pneumonia.

Exercise is key for fall prevention and maintaining mobility. A member of our local support group was told by his wife’s movement disorder specialist that she lived an additional two years due to exercise on a special treadmill.

The medication that can be prescribed and any other treatments are focused on a few symptoms that may respond to medication or treatments such as depression, urinary incontinence, and dry eyes. There is no evidence that any of the Parkinso’s medications (levodopa therapy) or Alzheimer’s medications are helpful in CBD/CBS.

Go-To Organizations for CBD Education

A handful of organizations consistently deliver quality information about CBD. Click the link for each organization to review their web sites:

Organization NameCountryFocusWeb Address
CurePSPUSAIncrease awareness, fund research, educate health professionals, support patients & families
PSP AssociationUKSupport patients & families, provide education

CBD Top Resources

Brain Support Network continually reviews most of the resources available on CBD. In our opinion, these are the most helpful resources for families:

Atypical Parkinsonism Symposium

This symposium featured Dr. Irene Litvan, one of the world’s top experts on CBD, giving the keynote on atypical parkinsonism as well as the break-out session on CBS/CBD. This October 2012 Stanford University (SF Bay Area) event was recorded, and the video is available online. A DVD is available through CurePSP (sponsor of recording) or Brain Support Network (one of the organizers).

UCSF Memory & Aging Center Overview of CBD

This is a good overview of the signs and symptoms of CBD.

The AFTD Overview of CBS

This is a good overview of the three categories of clinical features of CBS.

Your Personal Guide to PSP (and CBD)

The first section of this 110-page booklet has an excellent introduction to PSP and CBD, with a focus on symptoms such as cognition/mood, mobility/falls, fatigue/ sleep, pain, swallowing, vision, and bladder/bowel. Other sections focus on the care team, caregiving, etc.  Published April 2013 by The PSP Association (UK). The group uses the term “PSP” as shorthand for both conditions.
Section 1:
Section 2:
Section 3:
Section 4:

UCSF PSP/CBD Research Update

This Februray 2014 conference focused on what UCSF Memory and Aging Center researchers have learned thus far about PSP and CBD, and what research is underway. Most of the eight talks are about 14 minutes in length.

CBD: Some Answers

3-page overview of CBD, written by the now-defunct WeMove organization. Available on CurePSP’s website, and last reviewed by them in April 2011.

Update on PSP and CBD

This update was given by neurologist Dr. Rajeev Kumar at the CurePSP family conference in Denver in October 2013. Recorded presentation is available online.

Challenges in the Management of CBD

This October 2010 update on CBD was given by Dr. Litvan, one of the world’s top experts on CBD. In this CurePSP webinar, Dr. Litvan reviews the three common clinical presentations of CBD. The recorded presentation is no longer available online.
Notes on webinar:

Behavior/Cognitive Issues with PSP, CBD & FTD

This CurePSP webinar was presented by Dr. Brad Boeve, one of the US’s experts on CBD, in April 2010. Dr. Boeve examines how various CBD symptoms are managed.
Notes on webinar:

Exploring diagnosis, management and best practice interventions in relation to PSP, MSA, and CBD

This November 2009 conference for allied health professionals (RNs, PTs, OTs, STs, social workers, etc) in Melbourne, Australia was recorded. One of the world’s top researchers of CBD, Dr. David Williams, based in Melbourne, is featured. The multi-hour conference is broken into 10-minute online video segments.  The first part of one segment is about CBD.

Notes on video:

A Guide for People Living with PSP, CBD, and Other Atypical Parkinsonian Disorders

122-page booklet from CurePSP, last updated in September 2012.

Finding Meaning with Charles

Book by Janet Edmunson, whose husband Charles had CBD.

Diagnostic Criteria

The diagnostic criteria listed in this section are derived from the paper Criteria for the diagnosis of corticobasal degeneration, Armstrong, et al. published in Neurology in 2013.

The paper explains CBD in terms of four distinct types (“phenotypes”) of the disease. These are:

  • corticobasal syndrome (CBS)
  • frontal behavioral-spatial syndrome (FBS)
  • nonfluent/agrammatic variant of primary progressive aphasia (naPPA)
  • progressive supranuclear palsy syndrome (PSPS)

Proposed clinical phenotypes (syndromes) associated with the pathology of corticobasal degeneration (“Table 4” in Armstrong, et al.)

Probable corticobasal syndromeAsymmetric presentation of 2 of:

a) limb rigidity or akinesia,

b) limb dystonia,

c) limb myoclonus plus 2 of:

  • d) orobuccal or limb apraxia,
  • e) cortical sensory deficit,
  • f) alien limb phenomena (more than simple levitation)
Possible corticobasal syndromeMay be symmetric: 1 of:

a) limb rigidity or akinesia,

b) limb dystonia,

c) limb myoclonus plus 1 of:

  • d) orobuccal or limb apraxia,
  • e) cortical sensory deficit,
  • f) alien limb phenomena (more than simple levitation)
Frontal behavioral-spatial syndromeTwo of:

a) executive dysfunction,

b) behavioral or personality changes,

c) visuospatial deficits

Nonfluent/agrammatic variant of primary progressive aphasiaEffortful, agrammatic speech plus at least one of:

a) impaired grammar/sentence comprehension with relatively preserved single word comprehension, or

b) groping, distorted speech production (apraxia of speech)

Progressive supranuclear palsy syndromeThree of:

a) axial or symmetric limb rigidity or akinesia,

b) postural instability or falls,

c) urinary incontinence,

d) behavioral changes,

e) supranuclear vertical gaze palsy or decreased velocity of vertical saccades

Proposed clinical phenotypes (syndromes) associated with the pathology of corticobasal degeneration (“Table 5” in Armstrong, et al.)

Clinical research criteria for probable sporadic CBDClinical criteria for possible CBD
PresentationProbable corticobasal syndromeAsymmetric presentation of 2 of:

a) limb rigidity or akinesia,

b) limb dystonia,

c) limb myoclonus plus 2 of:

  • d) orobuccal or limb apraxia,
  • e) cortical sensory deficit,
  • f) alien limb phenomena (more than simple levitation)
Minimum duration of symptoms (years)11
Age at onset (years)≥50No minimum
Family history (2 or more relatives)ExclusionPermitted
Permitted phenotypes (see table 4 for criteria)1) Probable CBS or
2) FBS or NAV plus at least one CBS feature (a–f)
1) Possible CBS or
2) FBS or NAV or
3) PSPS plus at least one CBS feature b–f
Genetic mutation affecting tau (e.g., MAPT)ExclusionPermitted