The sensory examination can be difficult to perform and interpret.

Patients may over report minor qualitative differences in an attempt to ‘help’ the examiner, provide inconsistent responses, or fail to appreciate what is being asked of them.

Some deficits may only be apparent when specifically tested for (e.g. parietal signs or positive Romberg test).

Directed testing to confirm or refute a predefined hypothesis can help avoid these pitfalls, for example, by specifically testing for a sensory level or ‘glove and stocking’ loss. Even so, the distribution of sensory loss can sometimes seem baffling and inconsistent with the rest of the diagnostic formulation. Reference to dermatome and peripheral nerve field charts, or the appreciation that the sensory signs and symptoms may be due to some other coexistent pathology (e.g. chronic diabetic neuropathy), will sometimes clarify matters.

It is sometimes worth considering whether the diagnosis is made clearer when the sensory signs are disregarded. Functional sensory symptoms can also cause confusion. Typical patterns of functional loss are a complete hemisensory disturbance, which returns abruptly to normal in the midline (although this can be seen with thalamic pathology) and widespread spinothalamic and dorsal column modality loss confined to a single limb (typically abruptly ‘cut off’ at the groin or shoulder). In many cases, the sensory examination mantra ‘do it last, trust it least’ proves sage advice.