From the Guidelines
Length-dependent sensorimotor polyneuropathy is a neurological disorder characterized by progressive damage to peripheral nerves that begins in the longest nerves of the body and advances in a symmetrical pattern, typically starting with symptoms in the feet and lower legs before gradually moving upward to affect the hands and arms, as noted in the most recent guidelines 1.
Key Characteristics
- The condition is characterized by both sensory symptoms (numbness, tingling, pain, or burning sensations) and motor symptoms (muscle weakness, cramps, or atrophy) 1.
- The "length-dependent" nature refers to how the longest nerve fibers are affected first due to their increased vulnerability to metabolic or toxic insults 1.
- Common causes include diabetes mellitus, alcohol abuse, vitamin deficiencies, certain medications, and hereditary factors 1.
Diagnosis and Assessment
- Diagnosis typically involves a thorough neurological examination, nerve conduction studies, and sometimes blood tests or nerve biopsies 1.
- Assessment for distal symmetric polyneuropathy should include a careful history and assessment of either temperature or pinprick sensation (small-fiber function) and vibration sensation using a 128-Hz tuning fork (for large-fiber function), as recommended in the latest standards of care 1.
- Annual 10-g monofilament testing is also recommended to identify feet at risk for ulceration and amputation 1.
Treatment and Management
- Treatment focuses on addressing the underlying cause when possible, such as improving glycemic control in diabetic neuropathy or discontinuing toxic medications 1.
- Symptom management often includes medications like gabapentin, pregabalin, duloxetine, or amitriptyline for neuropathic pain, with dosages tailored to individual patient needs 1.
- Physical therapy may help maintain muscle strength and function, while proper foot care is essential to prevent complications in patients with reduced sensation 1.
From the Research
Definition of Length-Dependent Sensorimotor Polyneuropathy
- A length-dependent sensorimotor polyneuropathy, also known as peripheral neuropathy, is a syndrome of diffuse, length-dependent, symmetric nerve dysfunction 2.
- It is characterized by sensory loss, pains, and motor deficit, with extensive sensory loss predominating in the distal limbs 3.
- The condition is linked with substantial morbidity, frequent healthcare utilization, and compromised quality of life due to related discomfort 2.
Clinical Features
- Typical neuropathic symptoms include pain, paresthesias, and numbness, particularly in the feet and calves 4.
- Clinical diagnosis is based on neuropathic symptoms and signs (deficits) 4.
- Sensory alterations are different among various types of diabetic neuropathies and are vital in diagnosis, following course, treatment options, and follow-up of treatment effects 5.
Pathophysiology
- The condition is associated with oxidative processes, and evidence suggests that alpha-lipoic acid (ALA) could mitigate the development of diabetic sensorimotor polyneuropathy (DSPN) and attenuate resultant symptoms and signs 2.
- The density of myelinated and unmyelinated axons is reduced in patients with length-dependent diabetic polyneuropathy (LDDP) 3.
- Regenerating axons are present in the nerves of patients with LDDP, but clinical improvement is not always observed 3.
Diagnosis and Management
- Diagnosis of DSPN is based on neuropathic symptoms and signs (deficits) 4.
- Management of DSPN includes lifestyle modification, optimal diabetes treatment, pathogenetically oriented pharmacotherapy, and symptomatic treatment of neuropathic pain 4.
- Quantitative examinations, such as nerve conduction study, corneal confocal microscopy, and intra-epidermal nerve fiber density, are useful in evaluating dysfunctions of large and small nerve fibers 6.