PRIMARY PROGRESSIVE FREEZING GAIT

Freezing gait is an incapacitating symptom often observed in patients with Parkinson's disease. It has been less frequently described in ass ociation with multi-infarct state, multisystem atrophies, and normoten sive hydrocephalus. In our movement disorder clinic, we have diagnosed (and followed up to 3 years; median, 16 months), 18 patients in whom progressive freezing gait was the sole neurological dysfunction. These 15 men and 3 women (aged 60-82 years; 74 +/- 6) were subjected to an extensive neurological work-up that included clinical evaluation, vide otaping for grading of gait disability, comprehensive blood and cerebr ospinal fluid (CSF) analysis, and brain computed tomography (CT) and m agnetic resonance imaging (MRI). Mean disease duration was 2.5 +/- 1.9 years (range, 0.5-6). Neurological examination disclosed freezing gai t, often associated with varying degrees of postural instability. The degree of freezing gait ranged from sudden motor blocks only when conf ronted with obstacles to severe disability with total inability to sta rt walking requiring a walker, massive assistance, or a wheelchair. Ho wever, patients could mimic gait movements with absolutely no freezing when seated or lying prone, and most of them could overcome arrests b y the ''walking-over-lines'' maneuver. Otherwise, neurological examina tion was normal with no signs of bradykinesia, rigidity, or tremor. Bl ood chemistry and CSF analysis were normal. Brain CT and MRI were norm al or showed mild cortical atrophy in 12 and putative lacunes in 6 pat ients. Therapy with levodopa or dopamine agonists was ineffective. Dur ing the follow-up period, a gradual progression of the freezing gait w as observed. However, it remained unaccompanied by any other neurologi cal findings. We therefore conclude that primary progressive freezing gait should be recognized as a distinct neurological entity, unique in its clinical presentation and natural course. The lack of response to levodopa raises the possibility that nondopaminergic pathways might b e involved.