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.