disorders of somatic sensation
Terms
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- parasthesia
- abnormal spontaneous sensations, such as burning, tingling, or pins and needles
- dysesthesia
- any unpleasant sensation produced by a stimulus that is usually painless
- numbness
- often used by pts to describe a sense of heaviness, weakness, or deadness in affected body part- and sometimes to signify any sensory impairment
- allesthesia
- a tactile or painful stimulus delivered on the side of hemisensory loss is experienced in a corresponding area of the opposite side
- anesthesia
- complete loss of touch appreciation
- hyperesthesia
- increased sensitivity to touch appreciation
- allodynia
- misperception of a trivial tactile sensation as pain; or more generally, when one stimulus evokes another type of sensation
- analgesia
- complete loss of pain perception
- hypalgesia
- partial loss of pain perception
- hyperalgesia or hyperpathia
- increased sensitivity to pain perception
- pallanesthesia
- loss of vibratory sense
- thermoanesthesia
- loss of temperature sensation
- primary sensory modalities
-
light touch
pinprick and temp
deep pressure
vibration
joint position - Romberg's test
- pt assumes a steady stance w/ feet together, arms outstretched, and eyes closed. observe for sway or fall. positive test indicative of grossly impaired joint position sense in legs
- two point discrimination
- pt indicates if he has been touched by one or two compass points, while distance is varied in order to determine shortest distance at which they are recognized as 2 points
- agraphesthesia
- inability to identify a number traced on the skin on palm of hand despite normal cutaneous sensation; implies lesion of contralat PL
- astereognosis
- inability to distinguish b/w various shapes or textures
- abarognosis
- inability to distinguish b/w different weights
- complex sensory fxs
- Romberg's test, 2-pt discrim, graphesthesia, stereognosis, abarognosis, bilateral sensory discrimination
- mononeuropathy simplex
- involvement of a single peripheral nerve
- mononeuropathy multiplex
- several individual nerves are affected, usu at random and noncontiguously
- polyneuropathy
- fx of multiple peripheral nerves is affected at the same time.
-
(polyneuropathies)
distal axonopathies - axon is principal pathologic target (most polyneuropathies)
-
(polyneuropathies)
myelinopathies - conditions involving myelin sheath
-
(polyneuropathies)
neuonopathies - principally affect nerve cell bodies in the anterior horn of the SC or dorsal root ganglion
- etiologies of peripheral nerve lesions
- hereditary, inflammatory d/o, neurotoxic exposure, metabolic d/o, neoplasm, connective tissue d/o, AIDS
- peripheral nerve pain
-
usually localized to region affected pathologically
-burning quality when sensory nerve involved; motor deficit if motor nerve involved. -
(peripheral nerve pain)
causalgia - severe, persistent pain, often burning in quality, that results from nerve trauma. oft radiates to greater territory than served by affected nerve. assoc w/ exquisite tenderness
-
(periph nerve pain)
reflex sympathetic dystrophy - sympathetically mediated pain syndromes precipitated by wide range of tissue injuries. intense pain out of proportion to injury that gets worse over time.
- radicular pain
- localization: distribution of one or more nerve roots. often exacerbated by sneezing, coughing, other maneuvers that increase intraspinal pressure; also maneuvers that stretch the affected roots.
- thalamic pain
- can lead to pain in all or part of the contralat half of body; pain of burning nature w/ particular unpleasant quality. aggravated by emotional stress. tends to dvlp when recovering from sensory deficit caused by underlying thalamic lesion. mild cutaneous sensation can produce unpleasant/painful sensations
- Dejerine-Roussy syndrome
- thalamic pain with a combination of sensory loss, spontaneous pain, and perverted cutaneous sensation.
- low back pain
- trauma, prolapsed disk, infections, neoplastic disease, paget disease, osteoporosis, arachnoiditis, referred pain, others...