INTRODUCTION AND EPIDEMIOLOGY
Key Clinical Questions
What are the symptoms and signs of peripheral neuropathy?
Which patients with peripheral neuropathies require hospitalization?
Which peripheral neuropathies are seen in the inpatient setting?
What are the common causes of peripheral neuropathies?
How are peripheral neuropathies evaluated?
What are the best treatment options for peripheral neuropathy?
Nontraumatic peripheral neuropathy is present in ~3% of the general population and in as many as 8% of individuals over the age of 55. Diabetes is the most common cause in developed nations, with vitamin B12 deficiency, thyroid dysfunction, and monoclonal gammopathy as other common causes. At least 60% of diabetics have objective evidence for peripheral neuropathy. Overall, diabetic neuropathy ranks third behind macrovascular disease and nephropathy in lifetime expenditures associated with diabetic complications. Neuropathy is responsible for more hospital admissions than all the other diabetic complications combined, and is a causative factor in up to 75% of all nontraumatic amputations.
PATHOPHYSIOLOGY AND CLINICAL FEATURES
Peripheral neuropathy is classified by the level of anatomical involvement (Table 213-1).
TABLE 213-1Patterns of Peripheral Neuropathy |Favorite Table|Download (.pdf) TABLE 213-1 Patterns of Peripheral Neuropathy
|Pattern ||Example |
|Radiculopathy ||Cervical, thoracic, lumbar, sacral |
|Plexopathy ||Brachial, lumbosacral |
|Mononeuropathy ||Median, ulnar, radial, axillary, femoral, peroneal, tibial, sciatic |
|Multiple mononeuropathies ||Mononeuritis multiplex |
|Polyneuropathy ||Motor, sensory, autonomic |
Radiculopathy affects the spinal root, leading to pain, paresthesias, and weakness in the distribution of the nerve root. It is most often caused by herniation of an intervertebral disk. Other causes include Lyme disease and neoplasia.
Plexopathy involves either the brachial plexus or the lumbosacral plexus, with symptoms involving multiple nerves. Causes include trauma, tumor infiltration, bony or vascular compression, radiation injury, and viral infection. Plexopathy may occur acutely in-hospital as a procedural complication, as in lumbosacral plexopathy due to groin hematoma after cardiac catheterization, or brachial plexopathy from stretch injury after cardiothoracic surgery.
Mononeuropathy is dysfunction of a solitary peripheral nerve. This is typically due to trauma (as in foot drop from peroneal nerve palsy after fibular fracture), compression (as in “Saturday night palsy,” compression of the radial nerve in the axilla from falling asleep with the arm draped over a hard surface, as seen in alcoholics), or entrapment (median nerve in carpal tunnel syndrome or ulnar nerve in cubital tunnel). Involvement of several noncontiguous individual nerves is referred to as multiple mononeuropathies or mononeuropathy multiplex; vasculitis is the most common cause.
Polyneuropathy affects many peripheral nerves simultaneously, with distal and more or less symmetric involvement. Symptoms typically begin in the feet, before ascending to involve the legs and hands. It may involve sensory, motor, and autonomic nerves, either in isolation or varying combinations. Sensory symptoms may be persistent or intermittent. Positive sensory symptoms (dysesthesias or paresthesias) are described as tingling, burning, ...