University:
Western Sydney University
Course:
MEDI 2003 | Clinical Sciences 2
Academic year:

2024
Views:

463

Pages:

2
Author:

Mariam A.

Disordered perception in the somatosensory system Hyperaesthesia  Heightened sense of touch.  Can be induced by peripheral or central sensitisation, such that a given stimulus is perceived as being more intense.  Hyperaesthesia to tactile stimuli can occur in some pain syndromes or anxiety. Palinaesthesia  Persistent sense of touch.  Subjective feeling of continuing presence and pressure of the object after releasing it, but such sensation never occurred spontaneously.  High-resolution T1-weighted MRI shows cortical atrophy in the right anterior parietal lobe and diffuse damage in the adjacent white matter.  Other areas affected are the postcentral and supramarginal gyri of the right hemisphere. Hypoaesthesia  Reduced sense of touch.  Can occur peripherally (e.g. nerve compression or entrapment) or centrally (e.g. stroke). Hyperalgesia  Increased sensitivity to pain, brought about through peripheral or central mechanism. Hypoagesia  Decreased sensitivity to pain (e.g. from behavioural therapy for cognitive pain). Allodynia  Pain produced by a non-noxious stimulus (e.g. light stroking).  Usually established peripherally (e.g. trigeminal neuralgia). Phantom limb pain  Pain perceived in an amputated limb.  Initially produced by nerve irritation at the neuroma which forms over the end of the cut nerve.  Can be maintained by central processes; reorganisation of the primary somatosensory cortex occurs with expansion of normally innervated area (e.g. face) into the denervated area (e.g. hand). o In some patients, stroking the face can induce sensations in the amputated hand. Perceived movements in phantom limb    By placing a vertical mirror on a table so that the mirror reflection of the patient’s intact hand is ‘superimposed’ on the felt position of the phantom. Movement of the mirror caused a perception of movement (kinaesthetic sensation). Some findings: o Repeated practice led to a permanent ‘disappearance’ of the phantom limb; hand became telescoped into the stump near the shoulder. o Relieved clenching spasms when mirror was used to facilitate ‘opening’; mirror was imperative for this occur. o Touching the normal hand evoked precisely localised touch sensations in the phantom; pronounced when patients actually ‘saw’ their phantom being touched in the mirror.