Clinical Presentation of Polyneuropathy
Polyneuropathy typically presents with symmetrical distal sensory or sensorimotor deficits that begin in the toes and feet and progress proximally in a length-dependent pattern, with symptoms including numbness, paresthesia, pain, and sometimes weakness. 1
Sensory Manifestations
- Symptoms usually begin symmetrically in the toes and feet, later progressing to fingertips as the condition advances 2
- Paresthesias, dysesthesias, and pain (often described as burning or tingling) are common early symptoms 2
- Symptoms are typically worse at the end of the day or at nighttime 2
- Small-fiber involvement causes pain and dysesthesia, while large-fiber involvement leads to numbness and loss of protective sensation 2
- Proprioceptive sensory loss contributes to gait imbalance 2
Motor Manifestations
- Muscle weakness typically begins distally, affecting toe extensors first, then ankle dorsiflexors 2
- Motor impairment is less common than sensory symptoms in many polyneuropathies 2
- When present, weakness is more prominent distally and may progress proximally 2
- Muscle wasting may occur in advanced cases 3
Physical Examination Findings
- Distal sensory loss with relatively symmetrical distribution 2, 1
- Reduced or absent deep tendon reflexes, proportional to sensory loss 2, 1
- Wide-based, unsteady gait due to proprioceptive deficits 2
- Assessment should include:
Autonomic Manifestations
- Orthostatic hypotension (fall in systolic or diastolic blood pressure by >20 mmHg or >10 mmHg upon standing) 2
- Gastrointestinal symptoms: alternating diarrhea and constipation, night diarrhea 2
- Urinary dysfunction: retention, incontinence 2
- Sexual dysfunction: erectile dysfunction in men; decreased sexual desire, increased pain during intercourse, decreased arousal, and inadequate lubrication in women 2
- Cardiovascular autonomic neuropathy may present with resting tachycardia (>100 bpm) 2
Diagnostic Testing
- Nerve conduction studies and electromyography are confirmatory tests showing diffuse abnormalities 2, 1
- Small-fiber neuropathy may not be detected by conventional nerve conduction studies and requires skin biopsy to determine epidermal nerve fiber density 2
- Sweat gland nerve fiber density may also be examined, along with Congo red staining for amyloid in specific cases 2
Patterns and Progression
- Most polyneuropathies develop over months to years, though some can progress rapidly 4
- Prevalence increases with age, reaching up to 7% in the elderly 5
- Symptoms typically do not subside between episodes and may severely affect normal daily activities 2
- Without treatment, polyneuropathy can progress from small-fiber to large-fiber involvement with increasing weakness, gait dysfunction, and eventually loss of ambulation 2
Common Mimics and Differential Considerations
- Carpal tunnel syndrome and lumbar stenosis/radiculopathy can cause similar patterns of numbness, pain, and weakness 2
- Carpal tunnel syndrome often precedes polyneuropathy by many years in some conditions 2
- Lumbar stenosis typically causes neurogenic claudication with symptoms after walking that improve with sitting/lying down (opposite pattern to polyneuropathy) 2
Etiology-Specific Presentations
- Diabetic polyneuropathy: Symptoms vary according to fiber class involved; small fiber involvement causes pain and dysesthesia, large fiber involvement causes numbness and loss of protective sensation 2
- Amyloid neuropathy: Initially presents as small-fiber neuropathy with early autonomic dysfunction; progresses more rapidly (15-20× faster) than diabetic neuropathy 2
- Chemotherapy-induced neuropathy: Predominantly sensory with elevated touch detection threshold, impaired sharpness detection, and altered thermal thresholds 2
Early recognition of polyneuropathy is critical as timely diagnosis and treatment can prevent progression and improve quality of life outcomes 2, 6.