Context: Polyneuropathy is a common disease and is more prevalent (at least 3 %) in elderly people. However, routine neurological examination of healthy elderly people may show distal sensory loss and absent tendon reflexes, which can obscure the distinction from polyneuropathy.
Objective: To investigate the relation between age and the prevalence of distal sensory loss, absent tendon reflexes, or muscle weakness, and to ascertain above which age these neurological signs could be considered as normal in ageing.
Data sources: PubMed, Embase, the Cochrane Library, and Current Contents from 1960 until 2004. Reference lists of relevant studies were searched for additional studies, reviews or textbooks.
Study selection: Studies reporting on neurological signs upon routine neurological examination in generally healthy adult persons were considered for inclusion. Two reviewers independently assessed study eligibility and performed study inclusion. Of 629 studies initially identified, 50 (8 %) met the inclusion criteria.
Data extraction: Two reviewers independently performed data extraction and assessed study quality based on study design and the rigour by which confounding co-morbidity was excluded.
Data synthesis: The 50 included studies comprised a total of 9,996 adult persons. Assuming heterogeneity between studies, the prevalence data from different studies were pooled for separate age groups with a random-effects model. In healthy persons older than 60 years the prevalence of absent vibration sense at the big toes (29 % [95 % CI 18 % to 38%]) or ankles (15 % [95 % CI 11 % to 20%]), and absent ankle reflexes (23 % [95 % CI 16 % to 30 %]) was increased.
Conclusions: Self-declared healthy adult persons younger than 60 years do not have neurological signs. After the age of 60 absent vibration sense at the big toes or ankles, and absent ankle reflexes are more prevalent, although the majority does not have these neurological signs. It seems more appropriate to apply different diagnostic criteria for polyneuropathy in adult persons younger and older than 60 years.