Stroke causes disabilities. Besides the paralysis or problems controlling movement; problems using or understanding language; problems with thinking and memory and emotional disturbance, there’s another functional loss that people don’t often mention: the sensory disturbance.
Stroke patients may lose the ability to feel touch, pain, temperature, or position. Sensory deficits may also hinder the ability to recognize objects that patients are holding and can even be severe enough to cause loss of recognition of one’s own limb.
Recent studies have provided evidence of the widespread incidence of sensory dysfunction following stroke. The incidence of sensory deficits in stroke is high ranging from 50% to 74%. The importance of these findings lies in the association between sensory loss post-stroke and poorer outcomes in motor capacity, functional abilities, length of inpatient stay, and quality of life.
Since literature suggests that clinicians can use information about patients’ sensory status to predict rehabilitation outcomes and select appropriate interventions, the accuracy of the sensory system assessment is extremely relevant. There are several measurement methods employed in the recovery of sensory disturbance, for instance, QST: “Quantitative sensory tests”, which are psychophysical in nature and the tests require cooperation from the patient. That means the patient must be cognitively competent, able to follow instructions and respond to the test stimuli. QST tests are not only an alternative or complementary study for the detection of sensory nerve abnormalities, but also techniques employed to measure the intensity of stimuli needed to produce specific sensory perceptions.
QST systems are separable into devices that generate specific physical vibratory or thermal stimuli and those that deliver electrical impulses at specific frequencies. The objective is to test the sensory threshold as follows for instance: a thermode (thermal stimuli surface) contacts the skin and the subject is asked to report sensation of temperature change or heat pain. An alternative stimulation modality utilizes electrical stimuli of variable frequency and intensity to determine sensory thresholds. QST could contribute and has the potential to further contribute to research of sensory dysfunction.
Apart from the loss of abilities, there’s another consequence that could not be ignored which seems to be quite on the contrary, however comes from the same origin. Some stroke patients experience pain, numbness or odd sensations of tingling or prickling in paralysed or weakened limbs, a condition known as paresthesia, a neurological skin disease.
Stroke survivors frequently have a variety of chronic pain syndromes resulting from stroke-induced damage to the nervous system (neuropathic pain). Patients who have a seriously weakened or paralysed arm commonly experience moderate to severe pain that radiates outward from the shoulder. Most often, the pain results from a joint becoming immobilized due to lack of movement and the tendons and ligaments around the joint become fixed in one position. This is commonly called a “frozen” joint; “passive” movement at the joint in a paralysed limb is essential to prevent painful “freezing” and to allow easy movement if and when voluntary motor strength returns. In some stroke patients, pathways for sensation in the brain are damaged, causing the transmission of false signals that result in the sensation of pain in a limb or side of the body that has the sensory deficit.
The loss of urinary continence is fairly common immediately after a stroke and often results from a combination of sensory and motor deficits. Stroke survivors may lose the ability to sense the need to urinate or the ability to control muscles of the bladder. Some may lack enough mobility to reach a toilet in time. Loss of bowel control or constipation may also occur. Permanent incontinence after a stroke is uncommon. But even a temporary loss of bowel or bladder control can be emotionally difficult for stroke survivors.
Moreover, sensory disturbance means loss of sight, hearing or the ability to communicate clearly; the results can be the same: a sense of isolation and loss. This section lists organisations working to help people deal with these feelings and find practical ways to carry on with their lives, in spite of their disabilities.
Stroke Rehabilitation Journal
American Academy of Neurology