Objective: To investigate the possible mechanism of amelioration of freezing of gait (FOG) in a patient with PAGF (Pure Akinesia with Freezing of Gait) by zolpidem.

Background: FOG is a challenging issue to be overcome in patients with parkinsonism and it is usually resistant to medications. Particularly in patients with PAGF, a rare clinical variant of progressive supranuclear palsy, the gait symptom is usually refractory to drug treatment. Furthermore, the mechanism of FOG is mysterious currently and remained to be elucidated. We recently encountered a 67-year-old female patient with PAGF whose FOG was improved dramatically by zolpidem. The neural mechanism was investigated.

Methods: Concomitant recording of 8-channel scalp EEG (FCz, Cz, Pz, C3, C4, P3, P4, EOG) and bilateral leg EMG (tibialis anterior and calf muscles) with sampling frequency of 8 KHz was performed during full-blown FOG and 1 hour after zolpidem when she can walk fluently in straight walking. EEG was filtered using a band-pass filter with cut-off frequencies of 1 to 50 Hz to get rid of the very low frequency drifting and high frequency noise. Then, the filtered EEG was down sampled to 250 Hz and further processed using independent component analysis (ICA). The electrode-component spectral map was plotted to identify the contribution of each component to the recording electrodes.

Results: Eight EEG components were identified by ICA. During FOG state, component-1 contributes almost equally to all recording electrodes and component-2 contributes mainly to FCz, Cz and P4. Component-6 and -7 contribute mainly to FCz and Cz. During zolpidem-on state, the contribution power of component-1 was diminished and the contribution from other components was no longer observed.

Conclusions: The source of EEG component-1 may arise from deep regions of the brain in regard of its widespread contribution to the recording electrodes and possibly the locomotion regions, including brainstem or basal ganglia, may be responsible to the source generation. Since zolpidem is a GABAergic agent, the basal ganglia GABA system could be crucial in this patient. On the other way the EEG component-2, -6, -7 sources may be located superficially and regions including the supplementary motor area, pre-motor cortex and schema formatting regions may engage in the generation of these sources.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/zolpidem-ameliorates-the-freezing-of-gait-in-a-patient-with-pagf-pure-akinesia-with-freezing-of-gait-the-possible-neural-mechanism/