Educational Guide for RAPID Users
Peripheral neuropathy often affects how a person senses pressure, loads their feet, and maintains balance. The RAPID Gravity Mat cannot diagnose neuropathy, but it detects functional signs of sensory loss by analyzing weight distribution, sway behavior, and response to biofeedback tasks.
This guide explains how each RAPID test works and what patterns may indicate sensory deficits worth further clinical evaluation.
1. RAPID Foot Decoding Test (Quiet Stance)
Purpose
To identify abnormal pressure distribution and postural stability during quiet standing.
What You Observe
Users with sensory deficits may show:
Left/right asymmetry
People often shift weight toward the more stable or less-affected side.Heel-dominant loading
Reduced forefoot sensation commonly leads to heavier heel pressure.Reduced micro-sway
Some individuals stiffen their posture to compensate for lost sensory feedback.OR excessive sway
Others rely more on visual or vestibular input and sway more than expected.
Key Parameters Collected
CoP (Center of Pressure) sway path length or velocity
Left vs. right loading (%)
Forefoot vs. heel pressure ratio
These metrics establish the user’s baseline stability and foot-loading pattern.
2. RAPID Clinical Test of Fall Risk (CTFR)
Purpose
To highlight sensory deficits by removing visual feedback. Testing involves two phases:
Eyes Open – Baseline balance
Eyes Closed – Stress test for sensory reliance
Typical Indicators of Sensory Impairment
When visual input is removed, individuals with neuropathy often demonstrate:
Increased sway velocity
Longer CoP path length
Difficulty maintaining quiet stance
Inconsistent pressure patterns
The CTFR is one of the most sensitive functional tests for detecting neuropathy-related balance challenges on the RAPID Gravity Mat.
3. RAPID Sensory Threshold Confirmation (Biofeedback Mode)
Purpose
To test whether the user can perceive and intentionally change pressure in specific foot regions.
How It Works
The RAPID system isolates regions on the mat (toes, heel, left foot, right foot, etc.).
The user is asked to shift pressure based on live CoP feedback:
Examples of instructions:
“Shift pressure into your toes.”
“Move weight into your right foot.”
“Increase heel pressure.”
“Tell me when you feel you made this change.”
What You Look For
Delayed response
Inaccurate pressure shifts
No reported sensation of change
Difficulty perceiving or controlling pressure changes supports the presence of sensory impairment.
How RAPID Reports Functional Neuropathy Indicators
Each assessment produces metrics that help clinicians identify atypical balance or loading patterns. The RAPID Gravity Mat report includes:
Asymmetry (%)
Forefoot / Rearfoot pressure ratio (%)
CoP sway velocity or path length
(Higher values generally indicate reduced sensory input or stability.)Regional force/pressure breakdown (%)
CoP plot patterns and direction
These data points help practitioners understand how the user loads their feet, compensates during balance tasks, and responds to biofeedback challenges. Lets take a look at some sample case studies to help understand how the system works.
Case Study 1: Early Sensory Decline with Mild Instability
Patient
Age: 58
History: Type 2 diabetes (12 years), occasional numbness in toes
Complaint: Feels “less steady” when walking in the dark
1. Foot Decoding Test (Quiet Stance)
Findings
Left/Right Loading: 60% left / 40% right
Forefoot/Heel Ratio: 35% forefoot (low), 65% heel
CoP Sway Velocity: Slightly elevated
Sway Pattern: Reduced micro-sway, stiffened posture
Interpretation
The user shifts weight toward the left (more stable side). Low forefoot loading and reduced subtle sway suggest reduced forefoot sensation and compensatory stiffening.
2. CTFR (Eyes Open → Eyes Closed)
Findings
Eyes Closed Sway: 35% increase in sway velocity
CoP Path Length: Moderately longer
Weight Pattern: Right foot becomes erratic when vision is removed
Interpretation
The user relies heavily on visual input for balance. When vision is removed, sensory deficits become more pronounced—common in early peripheral sensory loss.
3. Sensory Threshold Confirmation (Biofeedback)
Findings
When instructed to:
“Increase right forefoot pressure” → delayed response (2–3 seconds)
“Shift to toes” → patient unclear if enough pressure was applied
Interpretation
Delayed perception of pressure changes on the right forefoot suggests reduced tactile sensitivity.
Summary
Functional indicators (asymmetry, reduced forefoot loading, increased sway when vision is removed) support early sensory impairment, warranting further clinical evaluation.
Case Study 2: Moderate Neuropathy Patterns with High Fall Risk
Patient
Age: 72
History: Known diabetic neuropathy; previous fall
Complaint: “My feet don’t tell me where the floor is.”
1. Foot Decoding Test (Quiet Stance)
Findings
Asymmetry: 52% right / 48% left
Forefoot/Heel Ratio: 25% forefoot, 75% heel
CoP Sway Velocity: High
Sway Pattern: Wide, slow oscillations
Interpretation
Severe forefoot underloading and a heel-dominant stance show minimal forefoot sensory contribution. Large sway indicates instability despite conscious effort to stand still.
2. CTFR
Findings
Eyes Closed:
Sway velocity doubles
CoP path length increases by 80%
Patient must step to regain balance
Interpretation
Very strong dependence on vision. When removed, the user cannot maintain quiet stance—common in more advanced proprioceptive loss.
3. Sensory Threshold Confirmation
Findings
User cannot reliably detect:
Right toe pressure changes
Small changes in heel-to-toe weight shift
Lateral load adjustments
On-screen CoP changes are visible, but the user does not feel them.
Interpretation
Significant sensory impairment confirmed by lack of perception during controlled pressure tasks.
Summary
Results show severe sensory deficits and a high functional fall risk. Ideal for referral, targeted rehab, and ongoing monitoring.
Case Study 3: Balance Issues Not Primarily Sensory
Patient
Age: 44
History: Chronic ankle sprain on left side; no neuropathy risk factors
Complaint: Occasional instability during sports
1. Foot Decoding Test (Quiet Stance)
Findings
Asymmetry: 62% right load (offloading injured left side)
Forefoot/Heel Ratio: Normal
CoP Sway Velocity: Near normal
Pattern: Slight increase in lateral sway
Interpretation
Asymmetry likely due to mechanical/orthopedic compensation rather than sensory loss.
2. CTFR
Findings
Eyes Closed vs Open: Minimal difference
CoP Path Length: Normal range
Pressure Consistency: Stable and repeatable
Interpretation
Stable performance with eyes closed suggests intact sensory feedback.
3. Sensory Threshold Confirmation
Findings
Quick and accurate detection of:
Toe pressure commands
Heel loading
Left/right shifts
Interpretation
No functional sensory deficit detected. Difficulty is likely musculoskeletal.
Summary
Findings indicate balance issues related to orthopedic factors, not sensory impairment.
Case Study 4 — Early Sensory Decline
Patient Profile
Age: 60
Risk Factors: Type 2 diabetes
Complaint: “Hard to feel where my toes are.”
1. Foot Decoding Test (Quiet Stance — 20 sec)
Functional Interpretation
Forefoot underuse and subtle increase in sway suggest reduced forefoot sensory contribution.
Patient compensates with slight left weight shift.
2. Clinical Test of Fall Risk (CTFR)
Eyes Open
CoP Sway Velocity: 1.08 cm/s
CoP Path Length: 21.8 cm
Eyes Closed
CoP Sway Velocity: 1.59 cm/s
CoP Path Length: 31.5 cm
% Change in Velocity: +47%
% Change in Path Length: +44%
Functional Interpretation
Large increases when vision is removed indicate vision-dependent balance and subtle sensory loss.
3. Sensory Threshold Confirmation (Biofeedback)
Task: “Increase right forefoot pressure by 10%.”
Interpretation
Delayed perception and incomplete pressure shift → reduced sensory accuracy in right forefoot.
Overall Summary
Mild asymmetry
Forefoot underloading
Elevated sway, especially with eyes closed
Slowed sensory response
Functional indicators consistent with early sensory decline.
Case Study 5 — Advanced Sensory Impairment Pattern
Patient Profile
Age: 73
History: Known peripheral sensory disorder; prior fall
Complaint: “Floor feels soft or distant.”
1. Foot Decoding Test (Quiet Stance — 30 sec)
Functional Interpretation
Extreme heel loading + large sway amplitude → minimal plantar sensory contribution.
2. CTFR
Eyes Open
Sway Velocity: 2.01 cm/s
Path Length: 64.0 cm
Eyes Closed
Sway Velocity: 4.18 cm/s
Path Length: 128.2 cm
% Change in Velocity: +108%
Steps/Taps: 1 corrective step at 19 sec
Functional Interpretation
Doubling of sway and corrective step indicates vision-dependent balance and major sensory deficits.
3. Sensory Threshold Confirmation
Task 1: “Shift weight to left toes by 15%.”
Time to Initiate: > 5 sec
Achieved Change: 2%
Patient Perception: “I can’t feel anything changing.”
Task 2: “Shift weight from heels to forefoot.”
Mat detected shift: 7%
Patient perception: None
Interpretation
Even large CoP shifts are unperceived → severe sensory impairment.
Overall Summary
Marked instability
Very low forefoot sensory engagement
Strong vision dependence
Inability to perceive controlled pressure changes
Functional indicators consistent with advanced sensory deficits.
Case Study 6 — Mechanical Instability (Non-Sensory Origin)
Patient Profile
Age: 45
History: Chronic left ankle instability
Complaint: “Left ankle feels weak,” no sensory symptoms
1. Foot Decoding Test (Quiet Stance — 20 sec)
Functional Interpretation
Asymmetry appears mechanical, not sensory.
2. CTFR
Eyes Open
Sway Velocity: 0.74 cm/s
Path Length: 17.2 cm
Eyes Closed
Sway Velocity: 0.81 cm/s
Path Length: 19.1 cm
% Change in Velocity: +9%
Functional Interpretation
Minimal difference → intact sensory feedback.
3. Sensory Threshold Confirmation
Task: “Increase left forefoot pressure by 10%.”
Response Time: 0.9 sec
Achieved Change: 11%
Perception: Immediate
Interpretation
Strong sensory accuracy; instability likely orthopedic, not sensory.
Overall Summary
Asymmetry due to mechanical factors
Normal forefoot/rearfoot ratio
Stable sway metrics
Accurate perception of pressure shifts
Indicators consistent with mechanical instability, not sensory impairment.
Using RAPID metrics alongside clinical observation allows practitioners to identify functional patterns, tailor interventions, and monitor progress over time.