Table 4. Corticobasal degeneration.
| Areas | Findings/recommendations |
|---|---|
| Neuropathology | Aggregates of 4-repeat tau in astrocytes (astrocytic plaques), oligodendrocytes (coiled bodies), and neurons (neurofibrils) and, often, swollen achromatic neurons in typical distribution (neocortex and basal ganglia) |
| Clinical syndrome | Corticobasal syndrome (CBS, about 25% of cases, PPV about 25%): at least one cortical symptom (apraxia, loss of cortical sensitivity, alien limb phenomenon) and at least one extrapyramidal symptom (akinesia, rigidity, dystonia, myoclonus) Frontal behavioral-spatial syndrome (about 10% of cases, PPV low): executive dysfunction, behavioral or personality changes, visuospatial deficits Richardson’s syndrome (RS, about 40% of cases, PPV low): symmetric, axial, akinetic-rigid, levodopa-resistant parkinsonian syndrome with early-onset postural instability and vertical supranuclear gaze palsy Progressive non-fluent aphasia (PNFA, <5% of cases, ppv low): non-fluent speech production (<9 words beginning with s in 60 seconds) with agrammatism while retaining understanding of individual words |
| MRI results | Parietal lobe atrophy: focal, mostly asymmetric |
| Basic diagnostic evaluation | Levodopa test: poor responsiveness to levodopa Neuropsychological testing: for example, apraxia, pathological Frontal Assessment Battery (FAB), reduced verbal fluency (<9 words beginning with s in 60 seconds), executive dysfunction (<6 correct successive luria sequences) |
| Extended diagnostic evaluation |
123I-FP-CIT-SPECT/18F-Dopa-PET: asymmetric striatal dopaminergic denervation 99 Tc-HMPAO-SPECT/ 18 FDG-PET: asymmetric hypometabolism in striatum and parietal cortex 123 I-IBZM-SPECT: asymmetric postsynaptic striatal degeneration |
| Symptomatic treatment | Levodopa (3–4 × 100–200 mg): mild to moderate improvement of akinetic-rigid symptoms in about 35% of cases (evidence level 3, recommendation grade B) Botulinum toxin A: good improvement of focal dystonia in 70% of cases (evidence level 3, recommendation grade B) Baclofen (up to 40 mg/day): moderate improvement of dystonia in 7% of cases (evidence level 3, recommendation grade 0) Clonazepam (2–6 mg/day): moderate improvement of myoclonus in about 25% of cases (evidence level 3, recommendation grade B) Propranolol (80–120 mg/day, maximum dose 320 mg/day): moderate improvement of action/postural tremor in about 20 % of cases (evidence level 3, recommendation grade B) |
Evidence level 1 = randomized controlled study (studies); 2 = case-control study (studies); 3 = non-analytic case study (studies); 4 = expert opinion;
recommendation grade A = strong recommendation [should]; B = recommendation; 0 = open recommendation [can]
CBD, corticobasal degeneration; MRI, magnetic resonance imaging; PPV, positive predictive value; SPECT, single photon emission computed tomography;
PET, positron emission tomography