Shingles is more common among the elderly and immunocompromised; usually (but not always) pain is followed by appearance of a rash with small blisters along a single dermatome. It can be confirmed by quick laboratory tests. Acute Lyme radiculopathy follows a history of outdoor activities during warmer months in likely tick habitats in the previous 1–12 weeks. In the U.S., Lyme is most common in New England and Mid-Atlantic states and parts of Wisconsin and Minnesota, but it is expanding to other areas. The first manifestation is usually an expanding rash possibly accompanied by flu-like symptoms. Lyme radiculopathy is usually worse at night and accompanied by extreme sleep disturbance, lymphocytic meningitis with variable headache and no fever, and sometimes by facial palsy or Lyme carditis. Lyme can also cause a milder, chronic radiculopathy an average of 8 months after the acute illness. Lyme can be confirmed by blood antibody tests and possibly lumbar puncture. If present, the above conditions should be treated immediately.Although most cases of radiculopathy are compressive and resolve with conservative treatment within 4–6 weeks, guidelines for managing radiculopathy recommend first excluding possible causes that, although rare, require immediate attention, among them the following. Cauda equina syndrome should be investigated in case of saddle anesthesia, loss of bladder or bowel control, or leg weakness. Cancer should be suspected if there is previous history of cancer, unexplained weight loss, or low-back pain that does not decrease by lying down or is unremitting.
Spinal epidural abscess is more common among those with diabetes mellitus or immunocompromised, who use intravenous drugs, or had spinal surgery, injection or catheter; it typically causes fever, leukocytosis and increased erythrocyte sedimentation rate. If any of the previous is suspected, urgent magnetic resonance imaging is recommended for confirmation. Proximal diabetic neuropathy typically affects middle aged and older people with well-controlled type-2 diabetes mellitus; onset is sudden causing pain usually in multiple dermatomes quickly followed by weakness.Investigations
If symptoms do not improve after 4–6 weeks of conservative treatment, or the person is more than 50 years old, further tests are recommended. The American College of Radiology recommends that projectional radiography is the most appropriate initial study in all patients with chronic neck pain. Two additional diagnostic tests that may be of use are magnetic resonance imaging and electrodiagnostic testing. Magnetic resonance imaging (MRI) of the portion of the spine where radiculopathy is suspected may reveal evidence of degenerative change, arthritic disease, or another explanatory lesion responsible for the patients symptoms. Electrodiagnostic testing, consisting of NCS (nerve conduction study) and EMG (electromyography), is also a powerful diagnostic tool that may show nerve root injury in suspected areas. On nerve conduction studies, the pattern of diminished Compound muscle action potential and normal sensory nerve action potential may be seen given that the lesion is proximal to the posterior root ganglion.