Aiding Diagnosis of Normal Pressure Hydrocephalus with Enhanced Gait
Feature Separability Shanshan Chen, Adam T. Barth,
Maïté Brandt-Pearce, John Lach
Charles L. Brown Dept. of Electrical & Computer
Engineering
Bradford C. BennettMotion Analysis and Motor Performance
LabDepartment of
Orthopedic Surgery
Jeffery T. Barth , Donna K. Broshek, Jason R. Freeman, Hillary L. Samples
Department of Psychiatry and Neurobehavioral Sciences
Excessive accumulationcerebrospinal fluid(CSF)
Normal Pressure Hydrocephalus(NPH)
2Drains CSF toAbdomen
Surgical Implant
Treatment(Shunting)
Symptoms:Cognitive degradation
Gait DisturbanceUrinary Incontinence
Diagnosis?
Differential Diagnosis in Clinics
3
High Volume Lumbar Puncture (HVLP) procedure
Temporarily Drains CSF
Before HVLPBrain imagingCognitive skills assessmentsGait performance
After HVLPCognitive skills assessmentsGait performance
cf.
Current Clinical Gait Evaluation• 10m Walk with Stopwatch Timing
• Step Length• Step Time• Gait Speed• Subjective Observation from Clinicians
• Limitations• Low precision
• Incapable of capturing of subtle gait improvement• Short-term
• Subjected to fluctuations in gait performance• Incapable of capturing gradual gait improvement
4
Qualitative Patient Response
5Maximal Response
Gait
Perfo
rman
ce
∆𝑻=?
Longitudinal Timeline (days)
NPH Group
Individual NPH
Other DementiaGroups
HVLPCurrent observation time window
d
Confounding!
Platform and Data Collection
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• 6 Suspected NPH Subjects• 4 are diagnosed as NPH, 2 are not
• Inertial Sensor Nodes on Waist, Wrists, Lower Limbs• Validation
• Shunting record and following-up studies
TEMPO 3.1 System 6 DOF motion sensing
a wrist watch form factorDeveloped by the INERTIA Team
• Inertial Body Sensor Networks (BSNs)• Emerging Research on Gait Analysis using Inertial BSNs• Less Invasive and More Wearable
• Potential for continuous longitudinal analysis
Gait Feature Extraction -- Temporal Gait Features• Stride Time Standard Deviation• Average Double Stance Time • Neither Feature Separates the NPH Group and non-NPH Group
7NPH 1NPH 2
NPH 3NPH 4
Non-NPH 1
Non-NPH 2
0
0.1
0.2
0.3
0.4
0.5
0.6
Before HVLPAfter HVLP
Average DoubleStance Time (s)
NPH Subject after HVLPHealthy Subject
Gait Feature Extraction-- via Nonlinear Analysis
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• Different Diverging Rates of Different Gaits• Lyapunov Exponent (LyE)
NPH Subject beforeHVLP
NPH 1NPH 2
NPH 3NPH 4
Non-NPH 1
Non-NPH 2
0
1
2
3
4
5
6
7
Before HVLP
After HVLP
Lyapunov Exponent
Results: Nonlinear Gait Feature
9Lyapunov Exponent Gait Stability
Future Work• Larger Size Study• Clinical Interface in Development
• Visualization of the data• Interpretation of the data
• Longer-term Monitoring
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11Maximal Response
Gait
Perfo
rman
ce
Longitudinal Timeline (days)
NPH Group
Individual NPH
Other DementiaGroups
HVLPFuture Observation time window
𝒎𝒂𝒙 ∆
Future Work
Conclusion• Pilot Study
• Real system deployment on real subjects• Advanced Signal Processing with Domain Knowledge
• Identifying and extracting relevant features• Providing separability to aid clinical decision
• Exemplification
12
Thanks!