Corticobasal Degeneration

Original Editor - Mason Trauger
Top Contributors - Mason Trauger and Kim Jackson

Introduction[edit | edit source]

Corticobasal degeneration (CBD), sometimes called corticobasal ganglionic degeneration (CBDG), is a form of Parkinsonism, more specifically a Parkinson-Plus Syndrome. Parkinson-Plus Syndromes are a group of neurodegenerative disorders that present with symptoms typical of Parkinson's Disease (PD) (bradykinesia, apraxia, resting tremor, rigidity, etc.); however, they do not typically respond well to PD pharmacological management and have additional symptoms such as cognitive deficits, dementia, and cranial nerve involvement.[1] [2] The following video provides a brief (~3.5 minute) overview of CBD:[3]

Clinically Relevant Anatomy and Pathophysiology[edit | edit source]

Corticobasal degeneration is a type of tauopathy affecting regions throughout the cerebral cortex (with greater impacts to the frontoparietal cortex) and basal ganglia (specifically the striatum and substantia nigra). Common histopathologic findings with CBD are neuronal loss and "ballooned" achromatic neurons.[4]

Although the etiology of CBD is unknown, there are known trends associated with progressive neurodegenerative tauopathies. Tau is a protein that assists in providing structural stability to neuronal axons.[5] These proteins can either over-accumulate (aggregation; gain of function) and become toxic to neurons and glia, or can lose function, resulting in a loss of stability and inability to transport cellular contents.[5] In CBD, tau proteins appear to aggregate, and result in the formation of astrocytic plaques primarily in the cortex.[6]

Epidemiology[edit | edit source]

Due to the difficulty of antemortem diagnosis, the proposed numbers are likely to be underestimates.

  • Annual incidence rate: 0.62 to 0.92 cases per 100,000 people[7]
  • Prevalence: 5 to 7 per 100,000[7]

The age of symptom onset appears to range between 45 and 72.2 years, with a mean of 63.7 years[8]

Clinical Presentation[edit | edit source]

All Parkinsonisms present with symptoms of Parkinson's, including apraxia, rigidity, bradykinesia, tremor, and postural instability.[5] CBD is one pathological cause of the clinical condition known as Corticobasal Syndrome (CBS). Although there are multiple clinical criteria to diagnose CBS, the following are commonly used presentation criteria:[6]

  • Asymmetric presentation with insidious onset/gradual progress
  • Orobuccal/limb apraxia
  • Cortical sensory deficits
  • Alien limb phenomena
  • Limb rigidity or akinesia
  • Limb dystonia
  • Limb myoclonia
  • Behavioral and cognitive impairments
    • Executive function and memory; with preserved episodic memory
  • Language dysfunction:
    • Decreased speech fluency
    • Speech apraxia
    • Aphasia
  • Visuospatial dysfunctions including:
    • Visual agnosia
    • Oculomotor apraxia
    • Optic ataxia

Diagnostic Procedures[edit | edit source]

Diagnosing CBD is difficult due to the aforementioned collection of pathologies composing corticobasal syndrome. This term tends to be preferred at this time, as there is a relatively high rate of antemortem mis-diagnosis of CBD.[6] However, some diagnostic findings are consistent with the pathology of CBD.

Imaging such as an MRI, and to a lesser degree, a CT scan, can be used to assist in CBD diagnosis. The following are common CBD findings on MRI:[4]

  • asymmetric cortical atrophy (commonly posterolateral and medial frontal regions)
  • bilateral atrophy of the basal ganglia
  • atrophy of the corpus callosum
  • preserved brainstem anatomy

Nuclear medicine studies such as single-photon-emission computed tomography (SPECT) and positron-emission tomography (PET) may also demonstrate clinical features of CBD. A common pattern found in patients with CBD on PET scan is asymmetric frontoparietal hypometabolism, with the contralateral hemisphere to the onset of symptoms having the most hypometabolic clusters.[9]

The following is a ~15 minute podcast which describes the clinico-radiologic and pathologic evaluation of corticobasal syndrome:[10]

Medical Management[edit | edit source]

Presently, there is no cure for CBD; all medical interventions at this time are directed at symptom management, rather than disease management.

Pharmacological management: due to the resemblance to Parkinson's Disease, dopaminergic agonists such as levodopa or rotigotine are used to treat the motor effects of atypical parkinsonism. Although transdermal rotigotine may be effective in reducing these symptoms, it does not specify subtype efficacy; additionally, only 24% of patients with CBD demonstrated improvements with levodopa intervention. Dopaminergic interventions are also used sparingly due to the high likelihood of inducing adverse psychotic events. Benzodiazepams such as clonazepam, appear to be effective in combatting symptoms of myoclonus and dystonia. Ultimately, most effects of these drugs are considered unsatisfactory for the population as a whole. [11]

Botulinum Toxin Injections: In cases of dystonia, injections of botulinum toxin can provide pain relief and prevent skin damage, with the most promising effects on wrist dystonia. [11]

Physiotherapy Management[edit | edit source]

Based on the clinical presentation culminating in deficits in balance, communication, cognition, gross and fine motor control, a multidisciplinary approach is encouraged to address these functional deficits. Physiotherapy, Occupational Therapy, and Speech Therapy all have a role in patient care; communication/referral between specialties should be performed as appropriate.

The literature treating Parkinson-Plus Syndromes is relatively scant. However, recommendations for a comprehensive treatment plan involve:[12]

  • Encourage regular walking to maintain mobility and cardiovascular fitness
  • Implementation of a fall prevention program
  • Progressive strengthening with resistance training through early stages of disease progression
  • Utilization of motor learning principles (strategy training, avoiding initial dual tasking, constant, distributed, blocked practice, part training)

CurePSP presented an hour-long webinar on physical therapy intervention on progressive supranuclear palsy, corticobasal degeneration, and multiple system atrophy:[13]

The following are open-access case studies for patients with CBD:

Differential Diagnosis[edit | edit source]

The differential diagnosis list of CBD includes:[4][6]

Outcome Measures[edit | edit source]

The Cortical Basal ganglia Functional Scale (CBFS) is a novel rating scale assessing daily living experiences of individuals with 4 repeat tauopathies such as CBD. This scale is purported to have excellent clinimetric properties (test-retest reliability intraclass coefficient =0.93) to assess disability in physical, cognitive, and psychiatric domains.[14] The scale is currently owned by the International Parkinson and Movement Disorder Society; one can view and request permission to use the scale at the following link:

Any other outcome measure(s) selected for a patient with CBD will be not be validated for their diagnosis; however, based on the functional impairments, the following are some of the numerous options to track change over time:

Prognosis[edit | edit source]

Corticobasal degeneration has a rapid decline in function until death, with mortality being associated with the development of sepsis and pneumonia from immobility and dysphagia.[15]After symptom onset, life expectancy ranges from 2 to 13 years, with a median survival range of 6 to 8 years.[16]

Resources[edit | edit source]

References[edit | edit source]

  1. Mark MH. Lumping and splitting the Parkinson Plus syndromes: dementia with Lewy bodies, multiple system atrophy, progressive supranuclear palsy, and cortical-basal ganglionic degeneration. Neurol Clin. 2001;19(3):607-27
  2. Miyasaki JM. Treatment of Advanced Parkinson Disease and Related Disorders. Continuum (Minneap Minn). 2016;22(4):1104-16
  3. Neurology Shelf Exam and Board Review. Corticobasal Degeneration. Available from [Last accessed 1/24/2024]
  4. 4.0 4.1 4.2 Gaillard F, Botz B, Sharma R, Alsmair A, Bhandari , Thurston M, Smith D, Bell DJ, Jasne A, Di Muzio B, Luijkx Tim. Corticobasal degeneration [Internet]. 2023 [cited 23 January 2024]. Available from:,relatively%20preserved%20brainstem%20anatomy%205
  5. 5.0 5.1 5.2 Tsai RM, Boxer AL. Clinical trials: past, current, and future for atypical Parkinsonian syndromes. Semin Neurol. 2014;34(2):225-234
  6. 6.0 6.1 6.2 6.3 Parmera JB Rodriguez RD, Neto AS, Nitrini R, Dozzi Brucki SM. Corticobasal Syndrome: A diagnostic conundrum. Dement Neuropsychol. 2016;10(4):267-275
  7. 7.0 7.1 Constantinides VC, Paraskevas GP, Paraskevas PG, Stefanis L, Kapaki E. Corticobasal degeneration and corticobasal syndrome: A review. Clin Park Relat Disord. 2019;30(1):66-71
  8. Armstrong MJ, Litvan I, Lang AE, Bak TH, Bhatia KP, Borroni B, Boxer AL, Dickson DW, Grossman M, Hallett M, Josephs KA, Kertesz A, Lee SE, Miller BL, Reich SG, Riley DE, Tolosa E, Tröster AI, Vidailhet M, Weiner WJ. Criteria for the diagnosis of corticobasal degeneration. Neurology. 2013;80(5):496-503
  9. Pardini M, Huey ED, Spina S, Kreisl WC, Morbelli S, Wassermann EM, Nobili F, Ghetti B, Grafman J. FDG-PET patterns associated with underlying pathology in corticobasal syndrome. Neurology. 2019;92(10):e1121-e1135
  10. Neurology Journal. Clinico-radiologic and Pathological Evaluation of Corticobasal Syndrome. Available from: [last accessed 1/24/2024]
  11. 11.0 11.1 Caixeta L,Caizeta VM, Nogueira YL, Aversi-Ferreira TA. Pharmacological interventions in corticobasal degeneration: a review. Dement Neuropsychol. 2020;14(3):243-247
  12. Morris ME. Rehabilitation Approaches in Atypical Parkinsonism [PowerPoint presentation]. [cited 24 January 2024]. Available from:
  13. CurePSP. Physical Therapy for PSP, CBD, and MSA. Available from [Last acccessed 1/24/2024]
  14. Lang AE, Stebbins GT, Wang P, Jabbari E, Lamb R, Morris H, Boxer AL. The Cortical Basal ganglia Functional Scale (CBFS): Development and preliminary validation. Parkinsonism Relat Disord. 2020;79:121-126
  15. Grijalvo-Perez AM, Litvan I. Corticobasal degeneration. Semin Neurol. 2014 Apr;34(2):160-73.
  16. Saranza GM, Whitwell JL, Kovacs GG, Lang AE. Corticobasal degeneration. Int Rev Neurobiol. 2019;149:87-136.