NeuroStride
Overview Clinical detail Research view
PD
PD-Patient · Monitoring active
Parkinson's FOG Monitor › Patient session
At a glance
Freezing of gait — session summary
Bilateral ankle IMU · 128 Hz · 6 min 58 s recorded · IRB-approved protocol
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47 freeze episodes detected this session — 14% of monitoring time above clinical threshold. Longest episode: 4.8 s. Consider medication timing review.
Freeze episodes
47
+12 vs last
FOG burden
14%
of session time
Avg episode
2.4 s
Longest: 4.8 s
Detection latency
<300 ms
Pre-onset
Episode timeline — 6 min 58 s session
Each bar marks a detected freeze event by onset time
0:001:453:305:156:58
Bilateral freeze index over time
Threshold at 1.5 — red = FOG
Episode frequency by time-of-session
Events cluster in the middle third
Signal view
Anti-phase coupling — 30 s pre-freeze window
Left and right ankle gyroscopes should be anti-phase during normal gait
0 s10 s20 s30 s
Left ankle
Right ankle
Desynchronization region
FOG event log — top 10 by severity
Bilateral freeze index at peak · Duration · Severity classification
# Onset Duration Peak FI Severity
Mean freeze index
Freeze vs gait comparison
FOG data
1.22
Normal gait
0.48
Specificity
Algorithm on gait-only data
98.3%
1.7% false positive rate
on normal gait windows
Sensor placement
Bilateral ankle, sagittal plane
L
Left ankle · GyroX sagittal
R
Right ankle · GyroX sagittal
Spectral analysis
Power spectral density — normal gait
Energy concentrated in locomotor band 0.5–3 Hz
Locomotor 0.5–3 Hz
Freeze 3–8 Hz
Power spectral density — FOG episode
Energy shifts into freeze band during FOG
Locomotor 0.5–3 Hz
Freeze 3–8 Hz
Algorithm parameters
Bilateral Freeze Index — sliding window Welch PSD
Sampling rate
128 Hz
Window size
256 samples
2.0 s
Step size
16 samples
0.125 s
FI threshold
1.5
bilateral geometric mean
Key innovation — bilateral phase coherence
Single-sensor systems cannot compute inter-leg desynchronization
Standard single-sensor approach
Detects freeze only after onset. Computes freeze index on one leg. Cannot measure inter-limb coordination. Typical latency 800–1200 ms post-onset.
NeuroStride bilateral approach
Detects bilateral desynchronization ~500 ms before onset. Bilateral FI = geometric mean of both legs. Requires coordinated breakdown across both limbs — reduces false positives.
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