Peripheral Neuropathy Classification and Diagnosis

Introduction to Peripheral Neuropathy

Cranial neuropathies can involve the eighth, oculomotor, fifth, or seventh cranial nerves, according to the European League Against Rheumatism 1
Optic neuropathy includes both inflammatory optic neuritis and ischemic/thrombotic variants, as stated by the European League Against Rheumatism 1

Multifocal neuropathies often present with patchy, asymmetric sensory loss and weakness in different nerve distributions, as noted by the European League Against Rheumatism 1
Multiple individual nerves can be affected asymmetrically in multifocal neuropathies, often seen in vasculitis or other systemic inflammatory conditions, according to the American College of Rheumatology, although this fact is from Praxis Medical Insights, an alternative source is not available 2

Demyelinating neuropathy in IBD patients is proportionally more common in women, presenting with proximal and distal symmetrical weakness, as reported by the European Crohn’s and Colitis Organisation 3

Small-fiber neuropathy affects unmyelinated C-fibers and thinly myelinated Aδ-fibers, causing pain, burning sensations, tingling, and temperature sensation abnormalities, according to the American Diabetes Association 4
Small-fiber neuropathy can be diagnosed by skin biopsy demonstrating loss of intraepidermal nerve fibers when electrodiagnostic studies are normal, as stated by the European League Against Rheumatism 1
Large-fiber neuropathy affects myelinated Aα and Aβ-fibers, causing numbness, loss of vibration sense, loss of proprioception, and loss of protective sensation, as reported by the American Diabetes Association 4
Loss of protective sensation is a major risk factor for diabetic foot ulceration, according to the American Diabetes Association 4

Cardiac autonomic neuropathy affects cardiovascular autonomic regulation, presenting with resting tachycardia, orthostatic hypotension, and decreased heart rate variability, as noted by the American Diabetes Association 4
Cardiac autonomic neuropathy is associated with mortality independently of other cardiovascular risk factors, according to the American Diabetes Association 5

Up to 50% of diabetic peripheral neuropathy may be asymptomatic, making systematic screening essential to prevent foot ulceration and amputation, as reported by the American Diabetes Association 4
Peripheral neuropathy is a diagnosis of exclusion—always evaluate for treatable causes including vitamin B12 deficiency, hypothyroidism, toxins, renal disease, malignancies, infections, chronic inflammatory demyelinating neuropathy, inherited neuropathies, and vasculitis, according to the American Diabetes Association 4
Electrodiagnostic testing is rarely needed except when clinical features are atypical or diagnosis remains unclear, as stated by the American Diabetes Association 4
In IBD patients, peripheral neuropathy is very rare and treatable causes must be identified first, as reported by the European Crohn’s and Colitis Organisation 3

The American Diabetes Association recommends using an 11-point numerical rating scale as the primary grading tool for painful diabetic peripheral neuropathy, supplemented by objective neurological examination findings to assess severity 6
The 11-point Likert scale is the recommended standard for grading painful symptoms, where patients rate their pain from 0 (no pain) to 10 (worst possible pain), according to the American Academy of Neurology 6, 7
For clinical trial purposes, mean weekly pain scores between 4-10 on the 11-point scale indicate clinically significant painful neuropathy, as stated by the National Institute of Diabetes and Digestive and Kidney Diseases 6

Diabetic neuropathy is invariably symmetrical with a distal symmetric sensory pattern in a glove-and-stocking distribution, as noted by the American College of Physicians 8
Patients with asymmetrical symptoms require careful assessment for alternative etiologies beyond diabetes, according to the American Academy of Neurology 8

Neuropathy-specific quality of life scales, such as NeuroQol, Norfolk Quality of Life Scale, and Neuropathic Pain Impact on Quality-of-Life questionnaire (NePIQoL), are preferable to generic instruments, as recommended by the International Diabetes Federation 6, 7
The Hospital Anxiety and Depression Scale (HADS) should be used to evaluate the impact of painful symptoms on mood, as suggested by the American Psychological Association 6, 7