Symptom Finder - Paraesthesias, Dysesthesias and Numbness
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. 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. Excessive intake of vitamin B6 (Pyridoxine) may cause a peripheral neuropathy. Finally, nerve entrapments such as carpal tunnel syndrome need to be checked. Tingling of the third and fourth toes would suggest Morton neuroma.
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. Do not forget Polio and postpolio syndrome.
Spinal cord: Spinal cord tumors, pernicious anemia, and tabes dorsalis are the most important conditions to recall here. Be alert to a myelopathy associated with acute onset of numbness around the waist and lower extremities that may occur in scuba divers.
Brain: Transient ischemic attacks, 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, ultrasonography, 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.
A positive Tinel’s at the ankle or inflated blood pressure cuff test may confirm a tarsal tunnel syndrome. 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
1. CBC (anemia)
2. Chemistry panel (hypoparathyroidism, electrolyte disturbance, uremia)
3. Fluorescent treponemal antibody absorption (FTA-ABS) test (neurosyphilis)
4. Serum B12, thiamine, B2, B3, B6, and folic acid levels (pernicious anemia, nutritional neuropathy)
5. Schilling test (pernicious anemia)
6. Blood lead level (lead neuropathy)
7. ANA analysis (collagen disease)
8. Glucose tolerance test or HbA1C (diabetic neuropathy)
9. Urine porphobilinogen (porphyria)
10. Hair analysis for arsenic
11. Somatosensory evoked potentials (multiple sclerosis)
12. Spinal tap (neurosyphilis, multiple sclerosis, demyelinating
neuropathy, hypothyroidism, diabetic neuropathy)
13. Anticentromere antibody (scleroderma)
14. Muscle biopsy (periarteritis nodosa)
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. 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. Excessive intake of vitamin B6 (Pyridoxine) may cause a peripheral neuropathy. Finally, nerve entrapments such as carpal tunnel syndrome need to be checked. Tingling of the third and fourth toes would suggest Morton neuroma.
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. Do not forget Polio and postpolio syndrome.
Spinal cord: Spinal cord tumors, pernicious anemia, and tabes dorsalis are the most important conditions to recall here. Be alert to a myelopathy associated with acute onset of numbness around the waist and lower extremities that may occur in scuba divers.
Brain: Transient ischemic attacks, 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, ultrasonography, 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.
A positive Tinel’s at the ankle or inflated blood pressure cuff test may confirm a tarsal tunnel syndrome. 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
1. CBC (anemia)
2. Chemistry panel (hypoparathyroidism, electrolyte disturbance, uremia)
3. Fluorescent treponemal antibody absorption (FTA-ABS) test (neurosyphilis)
4. Serum B12, thiamine, B2, B3, B6, and folic acid levels (pernicious anemia, nutritional neuropathy)
5. Schilling test (pernicious anemia)
6. Blood lead level (lead neuropathy)
7. ANA analysis (collagen disease)
8. Glucose tolerance test or HbA1C (diabetic neuropathy)
9. Urine porphobilinogen (porphyria)
10. Hair analysis for arsenic
11. Somatosensory evoked potentials (multiple sclerosis)
12. Spinal tap (neurosyphilis, multiple sclerosis, demyelinating
neuropathy, hypothyroidism, diabetic neuropathy)
13. Anticentromere antibody (scleroderma)
14. Muscle biopsy (periarteritis nodosa)