Numbness and sensory disturbance

Published on 10/04/2015 by admin

Filed under Neurology

Last modified 10/04/2015

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Numbness and sensory disturbance

Sensory symptoms are very common, occurring in about 8% of the general population. Sensory symptoms and signs alone may lead to a diagnosis. They can also be very helpful in clarifying the diagnosis in patients with other symptoms and signs. However, sensory symptoms and signs are ‘softer’ than many other neurological symptoms and can occur without an established underlying cause.

Sensory symptoms and signs do not occur in diseases that solely affect muscle, the neuromuscular junction or anterior horn cell. Their presence therefore excludes these diagnoses (unless another incidental reason can be found for them).

Clinical features

Numbness, tingling or pins and needles are the commonest sensory symptoms. The terms mean different things to different patients: you need to establish what the patient means, the distribution of sensory loss and the time course of the problem.

image What is it?
image Where is it?
image How did it come on?

What is it?

Sensory symptoms can be broadly divided into:

image positive symptoms: an intrusive feeling of altered sensation, often referred to as numbness, tingling, pins and needles, though sensations may include pain
image negative symptoms: the realization that sensation is lost, usually noticed when the patient inadvertently touches the affected part.

Patients will often describe sensory disturbance as ‘numbness’ and this term alone can be used to mean:

image loss of sensation – a negative symptom
image a positive feeling of altered sensation – ‘like the sensation as a local anaesthetic wears off’
image pain

A limb may be described as numb when it is in fact weak, or vice versa.

Tingling or pins and needles can usually be readily recognized as a distinct sensory symptom. Usually this can be localized more accurately than other positive symptoms.

Loss of joint position sense (proprioception) is more likely to be described as clumsiness or unsteadiness or like having a tight bandage on rather than numbness. Cortical sensory loss is usually noticed because of the disturbance in function, with clumsiness or incoordination more prominent than sensory symptoms.

Negative sensory symptoms, or the finding of sensory loss without associated symptoms discovered on examination, occur particularly in the following situations:

image If the sensory loss is very longstanding or of slow onset, for example hereditary neuropathies.
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