Polyneuropathy in the Feet: When Tingling and Numbness Persist

What lies behind the condition

In medicine, polyneuropathy refers to a disease affecting multiple peripheral nerves in the human body. The peripheral nervous system encompasses all nerve pathways located outside the brain and spinal cord. These pathways conduct motor impulses from the central nervous system to the muscles and, in return, transmit sensations such as cold, heat, touch, and pain to the brain. In polyneuropathy, this signal processing is disrupted.

In the vast majority of cases, this process begins at the most distant nerve endings, known as the distal segments. Because the nerve fibres extending to the feet and toes are the longest in the entire human body, metabolic disorders or toxic damage manifest there first. Medical specialists refer to this as length-dependent, distal-symmetric polyneuropathy. The conductive pathways lose their insulating layer, the myelin sheath, or the inner nerve strand, the axon, degenerates.

Anatomically, a distinction is made between large-calibre A-beta fibres, which are responsible for vibration perception and fine mechanoreception, and thin C fibres and A-delta fibres. The latter transmit temperature signals and painful stimuli. If these thin fibres are damaged, natural protective sensation is lost. Although the skin still registers coarse pressure, it no longer signals harmful stimuli to the brain. Consequently, tissue injuries remain unnoticed, and the foot loses its sensory feedback to the gait apparatus.

Typical signs

The symptoms of polyneuropathy are varied and usually progress insidiously over months or years. Initially, so-called positive symptoms often dominate. Those affected feel an involuntary tingling reminiscent of ants crawling, or a burning sensation on the soles of the feet, which is referred to in medical literature as burning feet syndrome. Nocturnal calf cramps or hypersensitivity to light contact, such as from a bedsheet, are also characteristic early signs.

As the condition progresses, negative symptoms increasingly appear, reflecting the progressive loss of sensation. Sensitivity to fine touch, cold, and heat steadily decreases. Affected individuals perceive the ground under their feet as if walking through a thick layer of felt. The absence of vibration sensation also leads to gait instability, which becomes particularly noticeable in the dark or on uneven surfaces. The body can no longer provide precise feedback regarding the position of the joints in space.

Careful differentiation from other clinical conditions is medically essential. A herniated disc in the lumbar spine region (L5/S1) also causes abnormal sensations in the leg, but these usually occur unilaterally and along a specific dermatome. Peripheral arterial disease (PAD), on the other hand, causes pain related to poor circulation during exertion, with the skin typically appearing pale and cool, and foot pulses being weak or impalpable. In pure neuropathy, the foot pulses are generally well defined, while sensory perception is blocked.

Everyday causes

The causes of damage to the peripheral nerves are complex. By far the most common cause in the Western world is diabetes mellitus. Permanently elevated blood sugar levels (HbA1c value above 6.5 percent) cause metabolic breakdown products of sugar to deposit in the walls of the finest blood vessels. These so-called vasa nervorum supply the nerve fibres with oxygen and nutrients. If they are damaged, the nerves gradually atrophy.

In addition to diabetes mellitus, chronic alcohol consumption and neurotoxic substances play a significant role. Alcohol has a direct toxic effect on axons and simultaneously leads to a deficiency of B vitamins, particularly thiamine (vitamin B1) and cobalamin (vitamin B12). Similarly, cytostatic drugs used in chemotherapy can trigger chemotherapy-induced peripheral neuropathy (CIPN). Hypothyroidism, chronic renal insufficiency, and autoimmune diseases are also among the triggers.

In daily life, biomechanical factors accelerate complications. Ill-fitting footwear with a toe box that is too narrow creates local pressure peaks. Normally, the foot would respond to this pressure with evasive movements or pain. In the presence of polyneuropathy, this warning signal is absent. The tissue reacts to continuous pressure with excessive callus formation (hyperkeratosis). Under these callus caps, shearing forces often cause unperceived haemorrhagic cavities and deep tissue necrosis.

When medical clarification is required

Polyneuropathy must be evaluated by a neurologist and an internist to treat the underlying cause or slow its progression. If abnormal sensations occur, a specialist should be consulted promptly. However, specific alarm signals require immediate medical evaluation.

Sudden onset of paralysis or foot drop, where the tip of the foot drags along the ground while walking, indicates acute motor involvement. Likewise, any open skin lesions, blisters, skin discolouration, or weeping areas require immediate medical assessment. If the foot swells significantly, becomes overly warm, and turns red without a perceptible cause, neuro-osteoarthropathic changes are suspected, also known as Charcot foot. Without immediate pressure relief, the collapse of the foot skeleton is imminent.

What podiatric treatment can achieve

A podiatry practice fulfils a central protective and monitoring function for people with polyneuropathy. Because affected individuals can no longer adequately feel tissue damage, foot treatment requires the highest degree of anatomical knowledge and instrumental precision. In our practice for podiatry, we begin every initial treatment with a thorough assessment of the neurological status of the feet.

Standardised test procedures are used for this purpose. Using the Semmes-Weinstein 10-gram monofilament, we check for the presence of protective sensation at defined anatomical points on the sole of the foot. If the synthetic filament bends without the patient feeling the pressure, a relevant loss of sensation is present. We test vibration perception using a Rydel-Seiffer 128 Hertz tuning fork at the bony prominences of the first metatarsophalangeal joint and the malleoli. To check thermal perception, we use a testing device with a metal side and a plastic side.

The actual podologische Komplexbehandlung (comprehensive podiatric treatment) is performed completely atraumatically. Callus removal is carried out in controlled, wafer-thin layers using surgical scalpel blades of sizes 10 or 15, without injuring the healthy dermis. When shortening and smoothing the toenails, we work with high-speed micromotors and wet-grinding technology. The fine spray mist continuously cools the treatment site, thereby preventing thermal tissue damage that the patient would otherwise not feel due to neuropathy. As a sektorale Heilpraktikerin für Podologie (sectoral practitioner of podiatry), the treatment strategy can be specifically adapted as required.

In addition, we fabricate custom pressure-protection orthoses made of medical two-component silicone for mechanical misalignments. These orthoses provide lasting relief to vulnerable areas such as hammer toes or hallux valgus pressure points. Treatment intervals for patients with polyneuropathy are generally four to six weeks to remove recurrent hyperkeratosis in a timely manner. A treatment unit usually lasts between 45 and 60 minutes.

What you can do yourself

Daily self-inspection and care represent the most important pillar in the self-management of polyneuropathy. Because you can no longer rely on pain perception, your eyes must assume the monitoring function of the nerves.

• Perform a systematic visual inspection of the soles, heels, and spaces between the toes every evening, using a shatterproof hand or floor mirror if necessary.
• Never check the water temperature for a foot bath with your feet, but always with a bath thermometer, ensuring the temperature does not exceed 37 degrees Celsius.
• Apply moisturising foams or creams containing 10 percent urea to your feet daily, avoiding the spaces between the toes to prevent tissue maceration.
• Wear only socks without pressing inner seams and with a soft cuff, preferably made of cotton or merino wool, and change them daily.
• Thoroughly feel the inside of your shoes with your hand for foreign objects such as small stones, folded insoles, or damaged linings before putting them on.

Common mistakes

In podiatric practice, we regularly observe behaviours that lead to severe tissue damage despite good intentions. Many affected individuals underestimate the dangers posed by everyday heat sources or unsuitable foot care tools.

• Walking barefoot on carpets, tiles, or in the garden, as small glass shards, thorns, or thumbtacks can penetrate deep into the tissue without triggering a pain response.
• Using hot water bottles, heating pads, or hot foot baths to combat cold feet, which quickly leads to second- or third-degree scalds.
• Using sharp rasps, planes, callus blades, or chemical callus-remover plasters containing salicylic acid for home foot care.
• Purchasing new footwear in the morning, as foot volume changes throughout the day and shoes that are too tight cause severe pressure points by the afternoon.

Current research and medical context

The evidence regarding the prevention and therapy of neurological complications affecting the foot is clearly documented in medical literature. The National Clinical Practice Guideline on Neuropathy in Adults with Diabetes highlights that regular podiatric monitoring and treatment drastically reduce the risk of ulcerations and secondary damage [1]. Studies demonstrate that the loss of protective sensation is the strongest independent predictor for the development of foot ulcers [2].

Research into the efficacy of podiatric interventions proves that combining professional callus removal, orthopaedic pressure relief, and structured patient instruction can reduce amputation rates in high-risk patients by more than 50 percent [3]. Regarding chemotherapy-induced peripheral neuropathy (CIPN), recent work indicates that targeted sensomotor training stimuli and physical measures can support the recovery of nerve function [4]. Regular re-evaluation of vibration and pressure perception using monofilaments and tuning forks is internationally regarded as the gold standard in follow-up diagnostics [5].

Treatment in Memmingen

In our specialist practice FREITAG® Podologie GmbH in Memmingen, we care for patients with polyneuropathy from across the Unterallgäu, Allgäu, and Upper Swabia regions. Under the professional direction of Helga Maria Freitag, we offer medically sound, pain-free care tailored precisely to your specific symptoms.

Our practice is located at Kempterstr. 25 in 87700 Memmingen. We operate according to the highest hygiene standards and coordinate closely with your treating medical specialists when needed. If you notice changes in your feet or require regular medical foot care, you can reach out to us at any time via our contact page.

Orthopaedic footwear provision and biomechanical pressure relief

When nerve pathways lack the ability to provide feedback on pressure loads, walking generates extreme shearing forces under the metatarsal heads and the heel. The adjustment of footwear therefore represents a central element of prevention. Standard off-the-shelf shoes rarely meet the biomechanical requirements of advanced nerve damage.

Orthopaedic footwear for neuropathic feet utilizes multi-layered insole constructions. Ethylene-vinyl acetate (EVA) foams with a low Shore hardness of 15 to 20 Shore A serve as the base material to cushion impact loads. Overlying memory foams adapt precisely to the contour of the foot under body heat. This distributes plantar weight evenly across the entire surface of the foot and prevents localized pressure peaks.

Mechanical load limits are easily exceeded without sensory perception. A 62-year-old female patient from the Unterallgäu presented with painless hyperkeratosis under the second metatarsal head. Podiatric inspection revealed an underlying subcutaneous tissue defect caused by a rigid outsole lacking adequate rocker bottom functionality.

The construction of the outsole is crucial for pressure reduction. An integrated roller sole or butterfly pad shifts the rollover point backwards and relieves the forefoot skeleton during the push-off phase. The upper material of the shoe must be seamless. Soft calfskin or elastic textile materials provide sufficient flexibility, while an elevated toe box prevents friction on hammer or claw toes.

Physical therapies and proprioception training

Although damaged peripheral nerve fibres have limited regenerative capacity depending on the etiology, the neural plasticity of the central nervous system permits functional adaptations. Targeted physical measures and proprioceptive stimuli can stimulate remaining sensitivity. They significantly improve movement coordination in daily life.

Sensomotor training uses unstable surfaces such as foam cushions, balance pads, or balance boards. Patients perform targeted weight shifts under visual control using a mirror. The brain thereby learns to connect the reduced nerve signals from the soles of the feet more effectively with visual and vestibular input. Short sessions of ten minutes of daily practice show measurable success in stabilizing gait patterns.

Electrotherapeutic procedures offer a non-pharmacological option for reducing neuropathic dysaesthesia. High-tone frequency therapy (HTEMS) conducts medium-frequency electrical impulses into the tissue via large-surface shin and plantar electrodes. Unlike classic TENS therapy, high-tone therapy does not primarily act on the nerve pathways themselves, but positively influences cellular metabolism and microcirculation in the vasa nervorum.

Thermal training carries significant risks due to impaired temperature perception. Contrast baths or cold pours are therefore contraindicated. Conversely, tactile stimulation using dry stimuli is safe. The use of soft massage brushes, various fabric textures, or gentle micro-vibrations activates remaining A-beta fibres without risking tissue damage.

Wound prophylaxis and principles of neuropathic ulcer management

If the integrity of the skin barrier collapses due to sustained pressure, a neuropathic ulcer develops. These deep wounds develop preferentially at the points of maximum mechanical stress on the sole of the foot. Due to the absence of pain perception, such lesions often remain unnoticed by affected individuals for days.

Tissue breakdown usually does not begin on the skin surface, but in the deep layers of the plantar fat pad. Excessive shearing forces lead to microtrauma and haematomas within the tissue. Under an intact but heavily calloused epidermis, a pressure-induced cavity forms. Only when this callus cap opens does the extent of tissue necrosis become visible.

Bacteria invade the deeper tissues unnoticed. Staphylococci and Streptococci colonize the ulcer and can rapidly trigger cellulitis or infectious involvement of the bone. If a deep infection is suspected, immediate surgical and diabetological intervention is required alongside podiatric wound debridement.

Local wound management follows the principles of moist wound healing. Alginates or hydrofibres derived from algae absorb wound exudate and transform into a gel-like environment that promotes granulation. Polyurethane foam dressings protect moist wound margins from maceration. The most critical prerequisite for healing remains complete pressure relief. Special offloading shoes or orthoses immobilize the foot and redistribute weight to the lower leg until the ulcer is fully epithelized.