What types of abnormal muscle movements occur in frontotemporal dementia?

Abnormal Muscle Movements in Frontotemporal Dementia

Frontotemporal dementia presents with a wide spectrum of abnormal muscle movements, most commonly parkinsonism (occurring in 25-80% of patients), stereotypical movements, and various hyperkinetic disorders, with the specific pattern often indicating particular FTD subtypes or genetic variants. 1

Parkinsonian Features (Most Common)

The most frequent abnormal movements in FTD are parkinsonian features, which differ substantially from idiopathic Parkinson's disease:

Core Parkinsonian Signs

• Bradykinesia/akinesia - most common parkinsonian feature 1
• Parkinsonian gait and posture - frequently observed 1
• Rigidity - common, may be symmetric (unlike typical Parkinson's) 1
• Tremor - notably LESS common than in idiopathic Parkinson's disease 1

Syndrome-Specific Patterns

Corticobasal Syndrome indicators:

• Asymmetric rigidity 1
• Alien limb phenomenon 1, 2
• Unilateral dystonia 1
• Ideomotor apraxia 1

Progressive Supranuclear Palsy features:

• Vertical gaze palsy (downward more than upward) 1
• Absence of normal optokinetic nystagmus 1
• Slowing of downward saccades 1
• Postural instability 1
• Axial dystonia 2

Hyperkinetic Movement Disorders

Stereotypical Movements

Motor and vocal stereotypies are observed in up to 78% of patients with autopsy-proven FTD 3, making them extremely common but often underrecognized. These include:

• Frequent rubbing behaviors 4
• Repetitive motor patterns 4
• Some self-injurious acts 4
• Strong association with compulsive-like behaviors 4

Other Hyperkinetic Movements

• Chorea - occasional 3
• Orofacial dyskinesias - occasional 3
• Myoclonus (stimulus-sensitive) - occasional 1, 3
• Dystonia - particularly unilateral dystonia in corticobasal syndrome 1, 3

Motor Activity Level Changes

Beyond specific movement disorders, FTD patients commonly show:

• Hyperactivity - prevalent in 58.5% of behavioral variant FTD and 68.8% of semantic variant PPA 5
• Hypoactivity - less common (29.3% in bvFTD, 18.8% in semantic PPA) 5
• Excessive ambulation (can walk continuously for hours) 6

Motor Neuron Disease Features

When FTD overlaps with motor neuron disease (particularly with C9orf72 mutations):

• Asymmetric weakness 6
• Marked muscle atrophy (facial and limb muscles) 6
• Hyperreflexia 6
• Upper and lower motor neuron signs requiring EMG evaluation 1

Additional Neurological Signs to Assess

Primitive reflexes:

• Grasp reflex (non-specific) 1

Oculomotor abnormalities:

• Decreased velocity of saccades 1
• Smooth pursuit abnormalities 1

Cortical sensory deficits 1

Clinical Significance

Critical distinction: The parkinsonism in FTD is typically symmetric, axial, and poorly responsive to levodopa 7, unlike idiopathic Parkinson's disease. This poor levodopa response is an important diagnostic clue, though patients with Pick's disease pathology may show better response 8.

The presence of these movement disorders strongly points toward FTLD subtypes rather than primary psychiatric disorders 1, making their recognition crucial for accurate diagnosis. Movement disorders can present at any disease stage and often evolve over time, with parkinsonism typically appearing as a late additional feature while corticobasal syndrome more commonly presents early 8.