PARESTHESIAS, DYSESTHESIAS, AND NUMBNESS
Anatomically, tingling and numbness or other abnormal sensations in the
extremities result from involvement of the peripheral nerve, the nerve
plexus (brachial or sciatic), the nerve root, the spinal cord, or the brain.
When each of these is cross-indexed with the etiologies suggested by the
mnemonic VINDICATE, most of the causes can be developed (Table
49). Only the most important conditions are mentioned in this
discussion.
Peripheral nerve. Peripheral neuropathies from alcohol,
diabetes, and other causes are important in this category, but one should
not forget vascular diseases that may cause paresthesias, such as peripheral
arteriosclerosis, Raynaud syndrome, and Buerger disease. In addition,
metabolic disorders such as tetany and uremia should be considered. Chronic
acute inflammatory demyelinating polyneuropathy (Guillain–Barré
syndrome) is brought to mind here. Finally, nerve entrapments such as carpal
tunnel syndrome need to be checked.
Nerve plexus. The brachial plexus may be involved by the
scalenus anticus syndrome, a cervical rib, or Pancoast tumor. The sciatic
plexus may be compressed by pelvic tumors.
Nerve root. Herniated disks, spondylosis, tabes dorsalis,
and infiltration of the spine by tuberculosis, metastatic tumor, and
multiple myeloma need to be remembered here.
Spinal cord. Spinal cord tumors, pernicious anemia, and
tabes dorsalis are the most important conditions to recall here.
Brain. Transient ischemic attacks (TIAs), emboli, and
migraines are vascular diseases to remember in addition to the diseases that
affect the spinal cord. The aura of epilepsy is also important. One would
not want to miss brain tumors, abscesses, and toxic encephalopathy because
these are potentially treatable.
Approach to the Diagnosis
This would be the same as the workup of weakness in one or more
extremities. If the condition is in the hand, one would check for Tinel and
Adson signs and x-ray the cervical spine for a cervical rib or disk
degeneration. The next steps are nerve conduction studies and Electromyogram
(EMG). Objective signs of radiculopathy are a clear indication for an MRI or
cervical myelography, preferably combined with a CT scan. MRI may reveal
tiny disk herniations. With associated pain in certain roots, diagnostic
nerve blocks may be indicated. If there is coldness in the hand, a stellate
ganglion block may be helpful.
If the condition is in the lower extremity, a careful examination of the
arterial pulses, particularly the femoral, is performed. If these are
abnormal, a flow study or femoral angiography may be indicated. X-rays of
the spine to rule out a herniated disk or tumor of the spine are done
routinely. One must not forget a pelvic examination in a female. If other
neurologic signs are present, an MRI or CT scan may be necessary. When a
disk herniation is still likely, myelography should be ordered. EMG has the
same usefulness here as in the upper extremity. When a cerebral lesion is
suspected, a CT scan, MRI, and four-vessel angiography should be considered.
Other Useful Tests
-
CBC (anemia)
-
Chemistry panel (hypoparathyroidism, electrolyte disturbance,
uremia)
-
Fluorescent treponemal antibody absorption (FTA-ABS) test
(neurosyphilis)
-
Serum B12 and folic acid levels (pernicious anemia)
-
Schilling test (pernicious anemia)
-
Blood lead level (lead neuropathy)
-
ANA analysis (collagen disease)
-
Glucose tolerance test (diabetic neuropathy)
-
Urine porphobilinogen (porphyria)
-
Hair analysis for arsenic
-
Somatosensory evoked potentials (multiple sclerosis)
-
Spinal tap (neurosyphilis, multiple sclerosis)
-
Anticentromere antibody (scleroderma)
Pictures
Book Source Details
- Book Title: Differential Diagnosis in Primary Care
- Author(s): R. Douglas Collins MD, FACP
- Year of Publication: 2007
- Copyright Details: Differential Diagnosis in Primary Care, Copyright © 2007 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: Differential Diagnosis in Primary Care, Copyright © 2008 Williams & Wilkins.
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