Knee trembling during freezing of gait represents multiple anticipatory postural adjustments

Jesse V. Jacobs, John Nutt, Patricia Carlson-Kuhta, Marilee Stephens, Fay Horak

Research output: Contribution to journalArticle

139 Citations (Scopus)

Abstract

Freezing of gait (FoG) is an episodic, brief inability to step that delays gait initiation or interrupts ongoing gait. FoG is often associated with an alternating shaking of the knees, clinically referred to as knee trembling or trembling in place. The pathophysiology of FoG and of the concomitant trembling knees is unknown; impaired postural adjustment in preparation for stepping is one hypothesis. We examined anticipatory postural adjustments (APAs) prior to protective steps induced by a forward loss of balance in 10 Parkinson's disease (PD) subjects with marked FoG and in 10 control subjects. The amplitude and timing of the APAs were determined from changes in the vertical ground-reaction forces recorded by a force plate under each foot and were confirmed by electromyographic recordings of bilateral medial gastrocnemius, tibialis anterior and tensor fascia latae muscles. Protective steps were accomplished with a single APA followed by a step for control subjects, whereas PD subjects frequently exhibited multiple, alternating APAs coexistent with the knee trembling commonly observed during FoG as well as delayed, inadequate or no stepping. These multiple APAs were not delayed in onset and were of similar or larger amplitude than the single APAs exhibited by the control subjects. These observations suggest that multiple APAs produce the knee trembling commonly associated with FoG and that FoG associated with a forward loss of balance is caused by an inability to couple a normal APA to the stepping motor pattern.

Original languageEnglish (US)
Pages (from-to)334-341
Number of pages8
JournalExperimental Neurology
Volume215
Issue number2
DOIs
StatePublished - Feb 2009

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Gait
Freezing
Knee
Fascia Lata
Parkinson Disease
Foot
Muscles

Keywords

  • Anticipatory postural adjustment
  • Balance
  • FoG
  • Freezing of gait
  • Gait initiation
  • Parkinson's disease

ASJC Scopus subject areas

  • Neurology
  • Developmental Neuroscience

Cite this

Knee trembling during freezing of gait represents multiple anticipatory postural adjustments. / Jacobs, Jesse V.; Nutt, John; Carlson-Kuhta, Patricia; Stephens, Marilee; Horak, Fay.

In: Experimental Neurology, Vol. 215, No. 2, 02.2009, p. 334-341.

Research output: Contribution to journalArticle

Jacobs, Jesse V. ; Nutt, John ; Carlson-Kuhta, Patricia ; Stephens, Marilee ; Horak, Fay. / Knee trembling during freezing of gait represents multiple anticipatory postural adjustments. In: Experimental Neurology. 2009 ; Vol. 215, No. 2. pp. 334-341.
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