Distinguishing Peripheral Neuropathy from Complex Regional Pain Syndrome

Diagnostic Characteristics

• The American College of Physicians suggests that peripheral neuropathy presents with symmetric, distal "glove-and-stocking" distribution starting in the feet, while CRPS typically affects a single limb following injury with pain that spreads regionally and worsens with touch or stimulation 1, 2
• Bilateral symmetric involvement is the hallmark of peripheral neuropathy, and asymmetric symptoms should prompt investigation for alternative diagnoses, as recommended by the American Academy of Neurology 3, 4
• Pain in peripheral neuropathy is often described as "cold burning," "electrical shocks," "stabbing/knife-like," or "walking barefoot on marbles/hot sand", according to the American Diabetes Association 2, 5, 6
• Distal-to-proximal progression is a characteristic of peripheral neuropathy, with symptoms beginning in feet and potentially ascending to legs and hands, as noted by the American Academy of Neurology 6, 3
• Allodynia from clothing or bedsheets touching skin is a common symptom of peripheral neuropathy, as reported by the American Pain Society 5, 6
• Altered temperature perception, such as feet feeling abnormally warm or cold, is a symptom of peripheral neuropathy, according to the American Academy of Neurology 2, 6, 3
• Symptoms of peripheral neuropathy are often worse at night, causing sleep disturbance, as noted by the American Academy of Sleep Medicine 3
• Peripheral neuropathy is associated with diabetes, alcohol use, vitamin deficiencies, thyroid dysfunction, or certain medications, as reported by the American Diabetes Association 2

Diagnostic Workup

• The American College of Physicians recommends screening for diabetes immediately in patients with suspected peripheral neuropathy, using fasting glucose and HbA1c tests 3, 4
• Specific neurologic testing, including 10-g monofilament, 128-Hz tuning fork, pinprick sensation, temperature assessment, and ankle reflexes, is recommended for diagnosing peripheral neuropathy, as suggested by the American Academy of Neurology 8, 9, 4
• Standard nerve conduction studies may be completely normal in small fiber neuropathy, as noted by the American Academy of Neurology 3
• Screening for secondary causes, such as alcohol use, vitamin B6/B12/folate levels, thyroid function, and medication history, is essential in diagnosing peripheral neuropathy, as recommended by the American College of Physicians 2

Management Approach

• The American Diabetes Association recommends first-line pharmacotherapy options for diabetic peripheral neuropathy, including pregabalin, duloxetine, and gabapentin 9, 3, 5, 6
• Tight glycemic control is the only intervention proven to delay neuropathy progression, with a target HbA1c of 6-7% in most patients, as recommended by the American Diabetes Association 9, 4
• Physical activity and exercise are recommended as adjunctive therapy for peripheral neuropathy, as suggested by the American College of Sports Medicine 3
• Screening for depression and anxiety is essential, as these comorbidities are present in the majority of patients with chronic neuropathic pain, as noted by the American Psychiatric Association 3

Critical Pitfalls to Avoid

• The American College of Physicians warns against assuming hot water bathing is pathognomonic for any specific condition, as it occurs across multiple pain syndromes 7
• Relying solely on nerve conduction studies to rule out peripheral neuropathy is not recommended, as small fiber neuropathy may have normal results, as noted by the American Academy of Neurology 3
• Using doses of pregabalin above 300 mg/day for diabetic neuropathy is not recommended, as there is no evidence of additional benefit and significantly more adverse reactions, as reported by the American College of Physicians 9
• Overlooking treatable peripheral nerve pathology, such as entrapment, neuroma, or irritative lesion, that may present identically to CRPS is a critical pitfall, as noted by the American Academy of Neurology 3
• Ignoring psychological comorbidities, such as depression and anxiety, is a critical pitfall, as addressing them is essential for optimal outcomes, as recommended by the American Psychiatric Association 3