“Corticobasal degeneration” (Current Treatment Options)

This great overview of CBD was recently published. The lead author is Stephen Reich, MD, a neurologist at the University of Maryland in Baltimore. He was the chair of the CurePSP Board.

Here’s the abstract (or “Opinion statement,” as it’s called in the article):

Current Treatment Options in Neurology. 2009 May;11(3):179-85.
Corticobasal degeneration.
Reich SG, Grill SE.

Corticobasal degeneration (CBD) is a neurodegenerative disorder characterized clinically by a combination of cortical and basal ganglia signs. Pathologically, it is classified as a tauopathy. The most distinctive clinical feature is its unilateral or markedly asymmetric presentation; among parkinsonian syndromes, with rare exceptions, only Parkinson’s disease presents with such asymmetry. The most common presenting cortical features include apraxia (patients often complain of a “useless” limb), aphasia (usually nonfluent), parietal lobe sensory signs (agraphesthesia, extinction, astereognosis), frontal dementia, or myoclonus. Basal ganglia signs include rigidity, akinesia, limb dystonia, and postural instability.

The diagnosis is often challenging for three reasons: 1) The full complement of findings are rarely seen at presentation; 2) If CBD is not suspected, subtle but relevant findings (eg, extinction, language impairment, myoclonus, or apraxia) may not be searched for or appreciated; 3) The clinical picture of CBD has substantial overlap with a variety of other parkinsonian and dementing illnesses. The differential diagnosis includes Parkinson’s disease, progressive supranuclear palsy, frontotemporal dementia, primary progressive aphasia, and Alzheimer’s disease. The clinical diagnosis is not confirmed pathologically in up to half of cases, so the term corticobasal syndrome is often preferred during life, reserving the term corticobasal degeneration for pathologically verified cases.

Treatment of CBD is primarily supportive, and most patients die within 10 years of onset. Parkinsonian signs may improve to a modest degree with levodopa, clonazepam can suppress myoclonus, and botulinum toxin can relieve dystonia. Early speech therapy, physical therapy, and occupational therapy, as well as assist devices such as a rolling walker may improve functioning and reduce complications such as aspiration pneumonia and falls. With time, however, most patients lose their independence and mobility. Throughout the course of the illness (particularly when it is advanced), caring for the caregiver is as important as caring for the patient.

PubMed ID#: 19364452 (see pubmed.gov for this abstract only)

You may be in need of some definitions, as I was:
* apraxia: loss of the ability to execute or carry out learned purposeful movements, despite having the desire and the physical ability to perform the movements (wikipedia)
* aphasia: loss of speech (or difficulty with speech); might also include loss of the ability to write (or difficulty writing)
* agraphesthesia: Inability to recognize letters or numbers drawn by the examiner on skin. The patients’ eyes are closed if this is done on skin visible to them. (wordinfo.com)
* extinction: when the conditional response no longer occurs i.e. salivating to the sound of a bell alone. (gerardkeegan.co.uk)
* astereognosis: a loss of the ability to recognize objects by handling them (wordnet.princeton.edu)
* akinesia: no movement or lack of movement

After reading the article, here are some new points for me:

* “…Togasaki and Tanner estimated that CBD accounts for about 5% of all cases of parkinsonism. The estimated incidence rate is 0.62 to 0.92 per 100,000 per year, with an estimated prevalence of 4.9 to 7.3 per 100,000, suggesting that about 20,000 people in the United States have CBD.”

* “Several reports have suggested that CBD may be more common in women.”

* “Other than PD, almost all other parkinsonian syndromes begin bilaterally, although not always symmetrically. In the typical onset of CBD, a limb (usually upper) gradually becomes “useless” or clumsy.”

* “One fourth of cases presented with difficulty walking. In our experience, this group represents a greater diagnostic challenge; it is not unusual for these patients to undergo unsuccessful shunting for presumed normal pressure hydrocephalus before more typical features of CBD either emerge or are tested for.”

* “…other challenging presentations include dementia (often confused with Alzheimer’s disease or frontotemporal dementia) and aphasia resembling progressive, nonfluent aphasia or apraxia of speech. Murray et al. demonstrated a typical cognitive profile of CBD: ‘…a characteristic impairment of gestural, executive, social, language, and visuospatial functioning but…normal recall and recognition memory even late in the course of the disease.’ The relative sparing of memory may help to distinguish CBD from frontotemporal dementia and Alzheimer’s disease.”

* “Rinne et al. emphasized the ‘striking rigidity, akinesia and apraxia of the affected limbs,’ and the dystonic postures were often accompanied by myoclonic jerks. Few other disorders have the distinctive picture of unilateral ‘jerky dystonia’.”

* “Almost half of the patients in this series demonstrated another feature of CBD, an alien limb. Such a limb is often described as ‘having a mind of its own,’ moving uncontrollably or seeming ‘foreign.’ Similarly, a limb in CBD may levitate, but levitation is not as specific for CBD as is the alien limb.”

* “Vidailhet et al. had previously demonstrated that there is no actual paralysis of vertical saccades in CBD, as occurs in PSP along with saccadic slowing; instead, patients with CBD demonstrate a prolonged latency prior to initiating a saccade. Thus, some patients with CBD may be mistakenly thought to have ophthalmoplegia if not given sufficient time or stimulation to generate a saccade. Unequivocal slowing of vertical saccades (often best demonstrated by testing optokinetic nystagmus) or vertical supranuclear ophthalmoplegia early in the course suggests PSP rather than CBD.”

* “It is often assumed that parkinsonian syndromes like CBD ‘don’t respond’ to levodopa, but this is not entirely accurate, as there may be some improvement early in the disease course. Kompoliti et al. reported a modest benefit with levodopa in up to 24% of patients. There is a report of an autopsy-confirmed CBD patient who developed dyskinesias on levodopa, but in general, levodopa dyskinesias are rarely seen except in Parkinson’s disease and (less frequently) in multiple system atrophy.”

The full article can be purchased for $35 here:
http://www.treatment-options.com/home_j … urnalID=NE