Signs Associated with Peripheral Neuropathy
Peripheral neuropathy presents with a characteristic constellation of sensory, motor, and autonomic signs in a symmetrical "stocking-and-glove" distribution, with loss of ankle reflexes occurring early, followed by sensory deficits, and later motor weakness in advanced disease.
Sensory Signs
The sensory manifestations depend on which nerve fiber types are affected:
Small Fiber Involvement
- Impaired pinprick sensation 1, 2
- Reduced temperature discrimination (particularly cold sensation) 1
- Burning sensations and dysesthesias 2
- Hyperalgesia (exaggerated pain response to painful stimuli) 1
- Allodynia (pain triggered by normally non-painful stimuli like socks, shoes, or bedclothes) 1
Large Fiber Involvement
- Loss of vibration sense (tested with 128-Hz tuning fork) 1, 2
- Impaired proprioception (position sense at toe and ankle) 1, 3
- Numbness without pain 1
- Loss of light touch perception (10-g monofilament testing) 1, 2
- Patients often describe feet feeling "wrapped in wool" or "walking in thick socks" 1
Reflex Changes
Loss of ankle reflexes is an early and consistent finding 1, 3. The Achilles reflex is typically absent even with facilitation maneuvers, and this sign alone has high diagnostic value 3. Patellar reflexes may be preserved initially but diminish as neuropathy progresses.
Motor Signs
Motor involvement typically occurs later and includes:
- Weakness of small foot muscles 1
- Dorsiflexor weakness (difficulty lifting the foot) 1
- Distal muscle atrophy in advanced cases 4
- Altered gait and balance 5
Motor deficits are generally less prominent than sensory changes in most peripheral neuropathies 1, 2. If motor deficits exceed sensory findings, asymmetry is present, or progression is rapid, this warrants immediate neurologist referral as it suggests an atypical etiology 1.
Autonomic Signs
Autonomic neuropathy manifests across multiple organ systems 6:
Cardiovascular
- Resting tachycardia 6
- Orthostatic hypotension (dizziness, lightheadedness, or weakness with standing) 6
- Syncope 6
Gastrointestinal
- Gastroparesis (erratic glycemic control, early satiety) 2, 6
- Constipation or diarrhea 6
- Fecal incontinence 2, 6
Genitourinary
- Erectile dysfunction in men 6
- Neurogenic bladder (urinary retention, incontinence, nocturia, urgency) 6
- Decreased sexual desire and arousal in women 6
Sudomotor
Distribution Pattern
The classic presentation follows a length-dependent, symmetrical pattern 4, 8:
- Symptoms begin in the toes
- Progress proximally up the legs in a "stocking" distribution
- When symptoms reach mid-calf, fingers become involved
- Progress up arms in a "glove" distribution
Structural Changes
Physical examination may reveal:
- Bony deformities (hammertoes, prominent metatarsal heads, bunions) 5
- Callus formation (indicates areas of increased pressure) 5
- Erythema and warmth (suggests impending tissue breakdown) 5
- Limited joint mobility 5
Clinical Pitfalls
Up to 50% of peripheral neuropathy cases are asymptomatic 6, 7, making systematic examination essential. The 10-g monofilament test primarily detects advanced neuropathy and ulceration risk, not early disease 1.
Pain occurring predominantly at night is characteristic 1, and its absence does not exclude neuropathy. When evaluating for neuropathy, the presence of two or three key signs—absent Achilles reflex, reduced vibration sense (<10 seconds with 128-Hz tuning fork), and impaired position sense (<8/10 correct on 1-cm trials)—identifies peripheral neuropathy with 94% sensitivity and 84% specificity 3.