An individual’s sensation can be affected by stroke with either of the loss or reduced touch, the loss or reduced temperature sensation, hypersensitivity to sensation, the loss of sensation from the bladder or bowel, Paresthesia (Altered sensation) and Proprioception (the sense of the relative position of one’s own parts of the body).
If stroke damaged the victim’s right side of the brain or parietal or occipital lobe, he will be highly prone to problems with sensation. Damage to the parietal lobe (where the somatosensory cortex is located) and damage to the thalamus and brainstem (which relay sensory information to the cortex) can cause sensation issues. Sensory problems post stroke differ from one person to another. However, most common sensory impairment after stroke is detecting hot and cold.
Consequences of sensory loss
- Stroke survivors are at the risk of skin damage and burning due to loss or reduced temperature sensation.
- With hypersensitivity to sensation, the stroke survivor may become over sensitive to pain just by light touch or when moving. This may result in the clothing being uncomfortable or even painful next to the skin.
- The loss of sensation from the bladder or bowel may lead to incontinence problems.
- Paresthesia, an altered sensation such as numbness, tingling, aching, burning or ‘pins and needles’ may cause great discomfort and confusion.
- Proprioception (the loss or reduced ability to know where a body part is) may make walking more difficult even if the muscle movements are intact. Due to Proprioception, the survivor may not know when his foot is flat on the floor or turned at the ankle joint. Without sensation, the stroke victim’s movements will lack precision and control.
Although sensory loss following stroke is common, studies of existing somatosensory retraining programs are limited. Sensory re-education is broadly used by therapists to retrain sensory pathways or stimulate unused pathways. Sensory re-education also aims at teaching adaptive techniques to help the stroke survivors compensate for the sensory loss. Mirror therapy along with sensory re-education might also be used to help the brain perceive normal sensory input from the stroke survivor’s left side.
While sensory re-education techniques are used for the hands, the same principles can be used for the legs. Sensory re-education intervention employs specific, graded discrimination tasks, attentive exploration of stimuli with deliberate anticipation and quantitative feedback. Commonly prescribed sensory re-education exercises include Table-top Touch Therapy (touching objects with different textures), Texture Hunting (finding the objects without looking), Texture Handling (sensing how different objects feel), Temperature Differentiation and Sensory Locating.