When the affected limb is persistently numb after a stroke, and sometimes loses all feeling, whether this can be treated is the question caregivers and patients ask most often. Before answering, it is necessary to understand that “numbness” is not a single phenomenon. It may be sensory loss (impaired touch, pain, temperature or proprioception), it may be abnormal sensation (tingling and burning), or it may simply be ordinary nerve compression (postural, unrelated to the core problem of the stroke). The three are handled in quite different ways.
From the physiotherapy point of view, this article first sorts the numb hand, and then turns to the most important but most often neglected part of sensory loss: safety protection of the limb that cannot feel. For the mechanisms of sensory impairment, how proprioception drives motor control, and the evidence-based comparison of SENSe, mirror therapy and electrical stimulation, see the overview of sensory re-education after stroke. This article covers only sorting the symptoms and home safety, and does not repeat the method theory.
Telling the three kinds of numbness apart
The same numb hand can have very different mechanisms behind it. Only when the type is known is it clear whether the next step is to protect, to refer, or to recognise that it has nothing to do with the stroke:
Sensory impairment after stroke is very common and differs by modality: the different kinds of sensation are not necessarily all damaged at once, nor do they all recover at the same time. Research shows that impaired touch is found in about 7 to 53%, stereognosis in 31 to 89% and proprioception in 34 to 64%, and the degree of recovery differs by modality (Connell et al. 2008). A numb hand should therefore be assessed one item at a time by the therapist, and full natural recovery should not be assumed.
A simple way to tell them apart: if the numbness goes as far as no feeling and being unable to tell hot from cold, it is sensory loss, and the focus of management is safety protection. If there is tingling and burning, or it hurts at a touch, it is abnormal sensation or central post-stroke pain, and the focus is referral to the doctor. The two situations call for entirely different approaches and must not be mixed up.
Safety protection for sensory loss
For a numb hand caused by sensory loss, physiotherapy first protects the limb that cannot feel, and does not rush to restore feeling. Once the senses of pain and temperature have failed, the protective mechanism of pulling away at once on touching something too hot no longer works, and burns, long periods of pressure and unnoticed injuries can all happen, often not found until a red mark, blister or wound appears.
Hidden risks for a limb that has lost feeling
- Burns: because heat cannot be felt, contact with hot water, hot soup, a heater or a heat pack can burn the hand without the patient knowing
- Long periods of pressure: the same spot can be pressed for too long without any pain or numbness, which may break the skin and even cause a pressure sore
- Injuries that go unnoticed: knocks, pinches or cuts do not hurt, so treatment is easily delayed and inflammation sets in
Four key points of home safety
- A heating pad or hot water bottle must not be placed directly on a hand without feeling. Put a layer of cloth in between when keeping warm, and control the temperature and time
- Before washing hands or showering, test the water temperature with the good hand or the elbow, and never test hot and cold with the hand that has lost feeling
- Check the skin every day for red marks, blisters or damage, and pay particular attention to the nails and bony points
- Change position regularly, and do not let a hand or foot without feeling stay pressed in the same place for a long time
A hand without feeling should not hold hot things and should not be used to test water temperature. Keeping to these two rules at home already avoids most burns in the home. Every time hot or cold has to be tested, use the good hand, the elbow or a thermometer.
Impaired proprioception and weak muscles are not the same
Many caregivers treat a numb hand that cannot produce force as a weak hand and so concentrate on strength training. But a sensory input problem and a muscle strength output problem are two different things. A patient with impaired proprioception may not know where the affected limb is at that moment, nor how much force is being used. The problem is not that the muscles are not strong enough but that the brain does not receive feedback about the position and force of the limb, so movements are clumsy, the hand knocks into things, and the patient has to keep the eyes on the hand to confirm where it is.
Adding more strength training alone cannot solve a sensory loss. Where it is safe, the patient can be taught to use vision to confirm the position of the limb during exercise and positioning, as compensation, and then to rebuild sensation step by step with sensory re-education. How sensory input drives motor control is not repeated here, and is covered in the overview of sensory re-education. The scientific background of neural remodelling after stroke is covered in the theory of stroke rehabilitation.
What sensory re-education can and cannot do
Only once safety protection has been done well does the next step of rebuilding sensation begin. Sensation can be retrained, but the strength of the evidence differs between approaches:
- Structured recognition of texture, limb position and objects, and not just passive contact
- Significantly improves sensory ability compared with non-specific sensory exposure, with the effect lasting six months (Carey et al. 2011)
- An evidence-based approach to sensory re-education that deserves priority
- Sensory stimulation applied passively, with no need for the patient to discriminate actively
- Moderate evidence on measures of upper and lower limb activity (Schabrun & Hillier 2009; Serrada et al. 2019)
- Can be used as a supplement, but the evidence for active sensory training is still limited, so do not over-promise
Sensory re-education is worth doing but should not be exaggerated. It does not mean feeling will return quickly. It is an evidence-based way of rebuilding sensation in a structured manner, within safe conditions. Tactile discrimination training, which tells apart texture, shape and objects in a structured way, is the core part of SENSe-style perceptual learning. The evidence-based grading and choice among the methods (SENSe, mirror therapy and electrical stimulation) are in the overview of sensory re-education, and this page does not rewrite the method details. For the overall strategy for upper limb motor recovery, see the overview of upper limb recovery after stroke.
What physiotherapy covers and when to refer
A numb hand is not something that one discipline of physiotherapy handles on its own. Knowing the scope of each discipline avoids going to the wrong person for help:
- If there is tingling or burning, or pain at a light touch (pain on touch), it may be central post-stroke pain, which needs assessment by the doctor or pharmacy, for example the use of an antidepressant or antiepileptic drug
- If the patient often cannot find his or her own hand, keeps knocking into things, or has spatial neglect and problems adapting daily self-care (ADL), this belongs to occupational therapy
- If the skin has blistered, there is a wound or there are signs of inflammation or infection, seek medical help at once and do not delay
- Safety protection education for sensory loss, positioning of the hands and feet, and sensory re-education supported by evidence fall within the scope of physiotherapy
- Teaching the patient to look to confirm the position of the hand and foot, and preventing burns and pressure at home, are all within the scope of physiotherapy
The overall prevalence of central post-stroke pain is about 11%, and in the subgroup with a thalamic or medullary stroke it can exceed 50%. Its usual features are tingling, burning and pain on touch, and first-line management is with antidepressants or antiepileptic drugs (Liampas et al. 2020). A numb hand with abnormal sensation must therefore be referred to the doctor. Spatial neglect (cannot find the hand) and adaptation of ADL belong to occupational therapy after stroke, and this page speaks only about sensation and safety education from the physiotherapy point of view.
A daily safety checklist for caregivers
The safety of a limb without feeling is kept up by small actions repeated every day. The checklist below can be put up where it is easy to see, and carried out by the main caregiver:
A checklist for preventing burns and pressure sores in Hong Kong homes
The principles above are put into a practical checklist for Hong Kong homes in this section. Once a hand without feeling has lost the protective senses of pain and temperature, burns and pressure sores often form without anyone noticing. The checks below follow the common high-risk places (water heaters, heaters and hot packs, long periods of pressure in a wheelchair, and bath water temperature). It is generally advised to make the things to do (tick) into house rules and treat the things not to do (cross) as red lines, put up in the kitchen and bathroom where they are easy to see, to be followed every day by the main caregiver. This is consensus practice for safety protection in sensory loss and cannot replace professional assessment.
- Set the water heater to a lukewarm temperature first, and do not turn it to the hottest at once. After turning on the water, always test the temperature with the good hand or the elbow, and never put the hand without feeling under the tap to test
- After cooking, the burner, the pot and the electric kettle are still very hot, and the hand without feeling must never touch or lean on them
- Do not pass or receive hot water, hot soup and hot tea just brought to the boil with the hand that has lost feeling, in case of spills and burns that go unnoticed
- Do not use the hand without feeling to test whether the flame or hot water is hot. That hand can no longer feel pain or heat, and by the time it touches, it is too late
- Keep the heater further away from seats and the bedside, at a safe distance from the hand or foot that has lost feeling, so that it is not warmed too long at close range without being noticed
- Hot packs and hot-water bags must not be placed directly on the skin of a hand or foot that has lost feeling. Put a layer of cloth in between, control the temperature and time, and take it off regularly to check the skin
- Do not use the hand without feeling to pick up a hot pack, switch on a heater or test how hot the heater outlet is. All these movements that need hot and cold to be told apart should be done with the good hand
- Do not sleep hugging a hot-water bag, and do not keep a heater on all night right beside the body. Even at a temperature that is not very high, contact with the skin for too long causes low-temperature burns just the same
- When sitting in a wheelchair or lying in bed for a long time, change position regularly to relieve pressure, moving or turning every so often, to avoid the same bony point being pressed for too long
- Take particular care over bony points such as the sitting bones, tailbone, heels and elbows. A place without feeling does not hurt however long it is pressed, and the skin can wear down or even form a pressure sore without warning
- Check whether cushions, shoes and supports have hard edges, creases or foreign objects pressing on a hand or foot that has lost feeling, because the patient may not feel it at all
- Do not assume all is well because the patient does not cry out in pain. Loss of feeling means exactly that it does not hurt, so the eyes and regular checks must be relied on
- After running the water and before getting in, always test the temperature with the elbow of the good arm or a thermometer. Better to keep the water lukewarm than to turn it to the hottest carelessly
- Set the shower temperature first, and only then let it run over the hand or foot that has lost feeling. Do not let water that goes suddenly hot and cold run straight onto it, in case of a burn that goes unnoticed
- After showering, check at once whether the skin without feeling is red or blistered. If any damage or blister is found, do not delay, and see a doctor if needed
- Never test the water temperature with the hand that has lost feeling, because testing with it is the same as not testing. To tell hot from cold, always use the good hand or a thermometer
The basic principle is that anything that needs hot and cold to be told apart, or needs a judgement on whether something is pressing, must never rely on a hand or foot without feeling. Testing water temperature, picking up hot things and testing how hot a heater is should all be done with the good hand, the elbow or a thermometer. To prevent pressure injuries, rely on regular turning and checking the skin every day, and do not wait until it hurts before changing position.