PARESTHESIAS OF THE LOWER EXTREMITY
Ask the Following Questions:
- Are the pulses diminished? The presence of diminished pulses should suggest peripheral arteriosclerosis or Leriche's syndrome.
- Is there associated pain in the involved extremity? The presence of pain in the involved extremity should suggest lumbar spondylosis, spinal stenosis, cauda equina tumor, spondylolisthesis, herniated disk, and pelvic tumors.
- Is there a positive straight-leg raising test and/or decreased Achilles reflex? These findings suggest a herniated disk of L4-5 or L5 to S1, lumbar spondylosis, spinal stenosis, a cauda equina tumor, or spondylolisthesis.
- Is there a positive femoral stretch test or decreased knee jerk? These findings suggest a herniated disk of L3-4 or L2-3 or lumbar spondylosis.
- Are there diffuse hyperactive reflexes? These findings suggest multiple sclerosis, pernicious anemia, degenerative diseases of the spinal cord such as syringomyelia, spinal cord tumor, or other space-occupying lesions. It may also suggest anterior spinal artery occlusion.
- Are there diffuse hypoactive reflexes? The presence of diffuse hypoactive reflexes would suggest poliomyelitis, Guillain-Barré syndrome, cauda equina tumor, metastatic tumor of the lumbar spine, and, occasionally, pernicious anemia or peroneal neuropathy. Also, peripheral neuropathy will present with diffuse hypoactive reflexes.
- Is there incontinence associated with the hypoactive reflexes? The presence of incontinence with the hypoactive reflexes may indicate poliomyelitis, cauda equina tumor, or metastatic tumors to the lumbar spine.
DIAGNOSTIC WORKUP
The basic diagnostic workup includes a CBC, sedimentation rate, urinalysis, chemistry panel, arthritis panel, VDRL test, and x-ray of the lumbosacral spine. A serum B
12
and folic acid should be done if pernicious anemia is suspected. If these tests are negative, an orthopedic or neurologic specialist should be consulted. A CT scan of the lumbosacral spine, a nerve conduction velocity study, and an EMG may all be necessary in the workup. MRI is more expensive and often unnecessary.
Combined myelography and CT scan is often useful in evaluating the need for surgery. A bone scan may be helpful in diagnosing occult fractures, metastases, or osteomyelitis.
If multiple sclerosis, Guillain-Barré syndrome, or central nervous system lues are suspected, a spinal tap may be done. SSEP studies are useful in diagnosing multiple sclerosis.
A neuropathy workup may be necessary. This involves a glucose tolerance test to rule out diabetes; urine tests for porphyrins and porphobilinogen to rule out porphyria; quantitative urine niacin, thiamine, pyridoxine, and other B vitamins after loading, an ANA and anti-dsDNA test to rule out collagen disease; serum protein electrophoresis and immunoelectrophoresis to diagnose various collagen diseases and macroglobulinemia; a lymph node biopsy and Kveim test for sarcoidosis; nerve conduction velocity studies and EMG to establish the presence of a neuropathy; thyroid profile to rule out hypothyroidism or hyperthyroidism; HIV antibody titers; blood levels for heavy metals such as lead to rule out lead or arsenic neuropathy; and skin and muscle biopsies to rule out various collagen diseases. A trial of therapy is often necessary to rule out the nutritional neuropathies.
Lumbar puncture, as already mentioned, is useful in diagnosing Guillain-Barré syndrome. Nerve biopsy may be necessary when all the above procedures are negative.
RBC transketolase activity is decreased in beriberi and the serum pyruvate and lactate levels are elevated.
Book Source Details
- Book Title: Algorithmic Diagnosis of Symptoms and Signs
- Author(s): R. Douglas Collins
- Year of Publication: 2003
- Copyright Details: Algorithmic Diagnosis of Symptoms and Signs, Copyright © 2003 Lippincott Williams & Wilkins.
Other Book Chapters Related to Paresthesias
Read excerpts from these other book chapters related to Paresthesias:
Medical Books Excerpts
- Paresthesia
- "Professional Guide to Signs & Symptoms (Fifth Edition)" (2006)
- [ read ]
- Paresthesia
- "Signs & Symptoms: A 2-in-1 Reference for Nurses" (2007)
- [ read ]
Copyright Details: Algorithmic Diagnosis of Symptoms and Signs, Copyright © 2008 Williams & Wilkins.
More About Causes of Paresthesias
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