Rigidity in corticobasal syndrome (CBS) is a distinct form of motor dysfunction characterized by increased muscle tone that is velocity-independent and often presents with unique features not seen in other parkinsonian syndromes. Unlike the "cogwheel" rigidity of Parkinson's disease, rigidity in CBS typically lacks modulation by voluntary movement and often exhibits distinctive patterns related to cortical and basal ganglia pathology.
Clinical Features
Characteristic Patterns
Velocity-independent tone increase: Increased resistance throughout passive range of motion
Uniform resistance: No "give" or ratcheting quality
Postural influence: Often modulated by limb position
Asymmetric onset: Typically begins on one side, reflecting cortical pathology
Distribution in CBS
| Region | Prevalence | Typical Pattern | |--------|------------|------------------| | Upper limbs | 70-80% | Proximal > distal, more affected side | | Axial | 50-60% | Neck and trunk paraspinals | | Lower limbs | 40-50% | Often later onset | | Face | 20-30% | Blepharospasm, orofacial dystonia |
Distinctive Features
cortical "set" rigidity: Increased tone when attempting voluntary movement on contralateral side
Paratonia: In some cases, involuntary resistance increases with caregiver attempts to move patient
Freezing: Often co-occurs with gait freezing
Pathophysiology
Neural Circuitry
...
Rigidity in corticobasal syndrome (CBS) is a distinct form of motor dysfunction characterized by increased muscle tone that is velocity-independent and often presents with unique features not seen in other parkinsonian syndromes. Unlike the "cogwheel" rigidity of Parkinson's disease, rigidity in CBS typically lacks modulation by voluntary movement and often exhibits distinctive patterns related to cortical and basal ganglia pathology.
Clinical Features
Characteristic Patterns
Velocity-independent tone increase: Increased resistance throughout passive range of motion
Uniform resistance: No "give" or ratcheting quality
Postural influence: Often modulated by limb position
Asymmetric onset: Typically begins on one side, reflecting cortical pathology
Distribution in CBS
| Region | Prevalence | Typical Pattern | |--------|------------|------------------| | Upper limbs | 70-80% | Proximal > distal, more affected side | | Axial | 50-60% | Neck and trunk paraspinals | | Lower limbs | 40-50% | Often later onset | | Face | 20-30% | Blepharospasm, orofacial dystonia |
Distinctive Features
cortical "set" rigidity: Increased tone when attempting voluntary movement on contralateral side
Paratonia: In some cases, involuntary resistance increases with caregiver attempts to move patient