The patient was a 51-year-old male who was referred for physical therapy due to balance and gait difficulties secondary to diabetic PN. He was referred to the Neurologic Wellness Program at Wingate University. The Neurological Wellness Program is a student run (pro-bono) clinic that provides exercise, gait, and balance training to people with neurological disorders who do not have health insurance or have exhausted their insurance.
His primary complaint was that his feet were numb. His past medical history included a 10-year history of type II Diabetes Mellitus, well-controlled with medication, mild back pain, peripheral neuropathy, high blood pressure, and kidney failure. He denied any falls in the past year. He complained of a not being able to feel his feet, walking on bricks, tingling, and pain. He had a diagnosis of primary sensory PN with moderate pain and generalized weakness. Prior to the diagnosis of PN, he was very active playing 20 h of tennis per week, roller blading and playing basketball. He was a truck driver for many years prior to his diagnosis and had to stop driving as he could not feel his feet.
He was alert and oriented, appeared cognitively intact and was a good historian. His medication included 81 mg aspirin, sertraline, Lisinopril, meclizine (due to generalized dizziness), pravastatin, chlorpromazine, Lyrica, omeprazole, Apidra, Lantus, iron, vitamin C, B12, and D3. His blood pressure was 150/98 with O2 saturation of 98%. His integumentary system was normal as was his range of motion except for ankle dorsiflexion to neutral bilaterally. Strength was generally 4/5 with the exception of ankle dorsiflexion which was 3+/5 bilaterally. He ambulated ~0.25 miles in the community with a straight cane and was independent in all mobility and ADLs. His light touch and sharp/dull sensation was impaired below the knee bilaterally. He was unable to detect the 50 g monofilament below the knee but was able to detect the 2 g above the knee. He was unable to detect the 128 Hz tuning fork at the great toe or the lateral malleolus, but it was intact at the knee bilaterally.
Due to the results of the systems review and observation of his gait in the clinic, the following special tests were completed; The Activities-specific Balance Confidence Scale (ABC), The Vestibular Activities of Daily Living Scale (VADL), 20' gait speed, Functional Gait Assessment (FGA), miniBESTest, Timed "Up & Go" (TUG), and cognitive TUG. The results of his initial scores on these tests are illustrated in Figures 1, 2. Although he was seen for 6 months prior to using Walkasins, multiple baseline values were not collected except for 2 measures for the FGA.
The Activities-specific Balance Confidence (ABC) test is a 16 item self-efficacy questionnaire that quantifies how confident people are in their ability to balance during the activities. The ABC is scored on a mean with scores ranging from 0 to 100 with higher scores indicating more confidence. The ABC is reliable and valid. The minimal detectable change (MDC) of the ABC is reported to be 11-15 points depending on the population. The ABC has not been evaluated in people with PN. The patient's score on the ABC prior to intervention was 32%.
The Vestibular Activities of Daily Living Scale (VADL) was developed to quantify a person's ability to perform daily activities and perception of assistance needed during functional activities that challenge balance. It contains 28 items ranging from bed mobility to driving a car. The VADL was developed to be scored on a median so that an item can be skipped without affecting the score. We scored it on both a median and mean to increase its responsiveness. The reliability and validity of the VADL has been demonstrated in subjects with vestibular dysfunction although an MDC has not been established. The patient's mean score on the VADL prior to intervention was 3.5.
Gait speed was calculated on a 20' walkway with ~4' acceleration and deceleration space. Calculation of gait speed is considered reliable and valid. A gait speed of 1.2 m/s is necessary to cross the street. The MDC for gait speed is 0.09 m/s for people with Parkinson Disease and for those with Alzheimer's Disease, and 0.109 m/s in older adults. The patients preferred gait speed was 0.21 m/s prior to intervention. He ambulated with a straight cane in the community.
The Functional Gait Assessment (FGA) was initially developed to quantify gait tasks in people with vestibular dysfunction. It includes 10 tasks, including gait at normal, slow and fast speeds, gait with head turns, turning, stepping over obstacles, walking tandem, eyes closed, backwards, and stairs, rated on an ordinal scale. It has been shown to be reliable and valid in many populations. The MDC of the FGA has been calculated to be 4 points in people with Parkinson's Disease and 6 points in people with vestibular disorders. The Minimal Clinically Important Difference in community dwelling older adults is 4. Scores of <22/30 indicate increased fall risk in community dwelling older adults. The patient's FGA score prior to intervention was 13/30.
The mini-BESTest was developed to guide treatment for balance disorders. It is a revision of the BESTest to decrease the time for administration. It contains 14 items scored on an ordinal scale of 0-2. It has been shown to be reliable and valid in various populations. Scores of <16 indicate increased risk of falling in older adults. The MDC for the mini-BESTest is 3.5 points in people with balance deficits. The patient's mini-BESTest score prior to intervention was 15/28.
Timed "Up & Go" (TUG) is the time it takes a patient to stand from sitting in a chair, walk 3 meters, turn, walk back to the chair and sit down. Times >11 s indicate increased risk of falls in older, community dwelling older adults. The MDC for the Timed "Up & Go" is 1 s in people with Type II Diabetes. The cognitive Timed "Up & Go" (cTUG) requires that a cognitive task such as counting backwards by 3's is performed while completing the test. A 10% difference between scores on the TUG and the cTUG is considered abnormal. His TUG score was 26 s, and his cognitive TUG was 37 s prior to intervention.
The Walkasins  is a sensory prosthesis that is intended to replace nerve function used to detect and signal balance related foot pressure sensation that is lost in patients with PN. It is indicated for use by individuals with lower limb sensory peripheral neuropathy who present with gait and balance impairments and are at high risk of falls. Pressure sensors embedded in shoe inserts measure plantar pressure, an embedded microprocessor and software estimates center of pressure parameters and activates a relevant tactile actuator around the ankle just above the malleoli providing directional specific information on center of pressure sway to help indicate the position of the body in space. During walking, relevant events of the gait cycle are signaled including heel strike and toe off allowing identification of the stance and swing phases of gait. The device is currently being investigated in a multi-site long-term clinical trial in a cohort of patients with PN (walk2Wellness, ClinicalTrials.gov #NCT03538756). The findings of the first 10 weeks in this trial of Walkasins has demonstrated improvement in gait and balance function in 45 adults with PN. Previous short -term studies including a recent in clinic randomized cross-over trial showed short-term improvements in gait and balance function.
The patient in the current study had been participating in a student run, pro bono neurological wellness program for 2 times a week over a period of 5 months and was receiving gait and balance training prior to the intervention with the Walkasins . Although he had seen some improvement in his gait and balance, he was no longer improving. FGA scores increased from 10 in October to 13 in January (Figure 1C). Based on this he was still at an increased risk of falls. He reported decreased visual acuity, due to macular edema, in addition to the peripheral neuropathy, so a decision was made to try the Walkasins  to evaluate its use to maximize his function. The use of the device was approved by the Research Review Board at Wingate University. The patient was fitted with the Walkasins  and was instructed in how to use the sensory information for balance by swaying with the eyes open and closed as well as walking. Despite his loss of sensory function below the knee, he was able to feel the vibration from Walkasins and use the information, therefore it was agreed that a trial of the device was warranted. The patient was able to use the information immediately and improvements in gait and balance measures were noted over time (see Figures 1, 2). The patient wore Walkasins  for more than 2 years while participating in the Neurological Wellness Program sporadically. He was aware of his scores on the outcome measures, completed a home exercise program of gait and balance exercises including encouragement to walk in the community, and received positive feedback as he improved.