From the Guidelines
The ability to feel a 5.07 monofilament at only 4 out of 10 sites on the plantar aspect of each foot indicates moderate to severe peripheral neuropathy, placing the patient at high risk for foot ulcers and injuries, and thus immediate intervention is recommended. This finding suggests significant loss of protective sensation, which is a major risk factor for foot complications in patients with diabetes 1. The 5.07 (10g) monofilament represents the threshold for protective sensation; inability to feel it at multiple sites indicates damage to large myelinated nerve fibers 1.
Key Recommendations
- Daily foot inspections to identify any potential issues early
- Proper footwear with cushioning to reduce pressure and risk of injury
- Regular podiatry care every 2-3 months for ongoing assessment and management
- Tight glycemic control if diabetes is the underlying cause, as this can help slow the progression of neuropathy
- Avoid walking barefoot to prevent injuries
- Promptly address any foot injuries, no matter how minor, to prevent infection and further complications
The pattern of sensory loss (affecting 60% of tested sites) suggests progression beyond early neuropathy, requiring vigilant foot care and possibly medication for neuropathic pain such as pregabalin 75mg twice daily, duloxetine 60mg daily, or amitriptyline 10-25mg at bedtime if painful symptoms are present 1. It is crucial for patients with neuropathy to have a visual inspection of their feet at every visit with a healthcare professional and to be educated regarding their risk factors and appropriate management.
From the Research
Ability to Feel 5.07 Monofilament
- The ability to feel a 5.07 monofilament is an important aspect of protective sensation in the feet, as determined by Semmes-Weinstein monofilament testing 2.
- A study on sensory thresholds of normal human feet found that the inability to feel a Semmes-Weinstein monofilament of 5.07 represents a sensory threshold that is more than 50 times greater than normal, indicating a significant loss of sensory ability 2.
- The same study found that sensation in the lesser toes and the arch were the most sensitive, followed by the hallux and the plantar metatarsal heads, while the heel was the least sensitive site 2.
Testing Protocol
- The study on sensory thresholds of normal human feet used a testing protocol where the Semmes-Weinstein monofilaments were applied to each site on the foot in an order of increasing stiffness, then repeated in decreasing order 2.
- The results showed that subjects had significantly better sensitivity when testing was performed from higher to lower monofilament stiffness, highlighting the importance of a consistent testing protocol 2.
Diabetic Neuropathy
- Diabetic neuropathy is a common complication of diabetes that can cause loss of sensation in the feet, increasing the risk of ulceration and other foot problems 3, 4, 5, 6.
- Studies have shown that gabapentin and pregabalin are effective treatments for painful diabetic neuropathy, but may have adverse cardiovascular effects with long-term use 6.
- The ability to feel a 5.07 monofilament at 4/10 sites on the plantar aspect of each foot may indicate some loss of sensation, but the exact implications of this finding are not clear without further context or comparison to normal values 2.