Pure Akinesia with Gait Freezing (PAGF), also known as primary freezing of gait, is a rare progressive neurological disorder characterized by the sudden, transient inability to initiate movement, particularly while walking. It is considered a variant of atypical parkinsonism and represents one of the clinical phenotypes of progressive supranuclear palsy (PSP)[1][2].
PAGF was first described as a distinct clinical entity in 2006 by Factor and colleagues, who identified patients with progressive gait freezing who did not meet criteria for Parkinson's disease (PD) or other known parkinsonian disorders. The condition is now recognized as part of the PSP spectrum, with many patients eventually developing classic PSP features[3].
The hallmark feature of PAGF is freezing of gait—a sudden, transient cessation of forward movement despite the intention to walk. Patients describe their feet as feeling "glued to the floor"[4].
Primary features:
Associated features:
PAGF typically follows a predictable pattern:
Approximately 50-70% of PAGF patients eventually develop classic PSP features, particularly vertical gaze palsy and axial rigidity[5].
PAGF is associated with neurodegenerative changes characteristic of PSP-type tauopathy:
The freezing of gait in PAGF involves dysfunction in multiple neural networks:
| Region | Role | Dysfunction in PAGF |
|---|---|---|
| Pedunculopontine Nucleus | Gait initiation | Tau deposition, neuronal loss |
| Basal Ganglia | Motor sequencing | Dopaminergic denervation |
| Supplementary Motor Area | Motor planning | Reduced activation |
| Frontal Cortex | Executive function | Executive deficits |
Proposed diagnostic criteria for PAGF:
Essential:
Supportive:
PAGF must be distinguished from other causes of gait disturbance[6]:
| Condition | Key Distinguishing Features |
|---|---|
| Parkinson's Disease | Tremor, asymmetric onset, sustained levodopa response |
| Progressive Supranuclear Palsy | Vertical gaze palsy, early falls, axial rigidity |
| Normal Pressure Hydrocephalus | Urinary incontinence, cognitive decline |
| Vascular Parkinsonism | Stepwise progression, cerebrovascular lesions |
| Drug-Induced Parkinsonism | Temporal relation to dopamine blockers |
| Functional Neurological Disorder | Inconsistent examination findings |
Limited efficacy is a hallmark of PAGF:
| Medication | Typical Response |
|---|---|
| Levodopa/Carbidopa | Minimal to partial benefit in ~30% |
| Dopamine agonists (pramipexole, ropinirole) | Variable, often limited |
| MAO-B inhibitors (selegiline, rasagiline) | Modest benefit in some |
| Amantadine | May reduce freezing episodes |
| Clozapine | Low-dose may help akinesia |
Physical Therapy is the cornerstone of management[7]:
Cueing Strategies can bypass freezing:
Assistive Devices:
Poor prognosis:
Relatively better prognosis:
Factor SA, et al. Pure akinesia with gait freezing: a clinical entity. Neurology. 2006;67(8):1518-1522. 2006. ↩︎
Gilman S, et al. Second consensus statement on the diagnosis of multiple system atrophy. Neurology. 2008;71(9):670-676. 2008. ↩︎
[Williams DR, Lees AJ. Progressive supranuclear palsy: clinicopathological concepts and diagnostic challenges. Lancet Neurol. 2009;8(3):270-279](https://doi.org/10.1016/S1474-4422(09). 2009. ↩︎
Nutt JG, Bloem BR, Giladi N, et al. [Freezing of gait: moving forward on a mysterious clinical phenomenon. Lancet Neurol. 2011;10(8):734-744](https://doi.org/10.1016/S1474-4422(11). 2011. ↩︎
Mahapatra RK, Edwards MJ, Schott JM, Bhatia KP. "Pure akinesia" as a feature of progressive supranuclear palsy. Mov Disord. 2004;19(3):365-369. 2004. ↩︎
Postuma RB, Berg D, Stern M, et al. MDS clinical diagnostic criteria for Parkinson's disease. Mov Disord. 2015;30(12):1591-1601. 2015. ↩︎
[Keus SHJ, Munneke M, Graziano M, et al. European Physiotherapy Guideline for Parkinson's Disease. 2014. ↩︎