Low frequency of post-lumbar puncture headache in demented patients.

The frequency of post-lumbar puncture headache (PLPH) was registered prospectively in 395 consecutive demented patients at a dementia diagnostic unit. The incidence of PLPH was low, occurring in only 8 patients (2.0%), the severity was mild, and the duration was less than 2 days in all cases but one. The reasons for this low frequency of PLPH in patients with dementia disorders may include disease- and/or age-related low pain sensitivity, rigid dural fibres and arteriosclerotic vessels, and large CSF space due to cerebral atrophy. Analysis of CSF is essential to identify secondary causes of dementia, preferentially chronic infections. The low frequency and severity of PLPH found in the present study shows that, with low risk of complications, lumbar puncture can be included in the routine clinical examination of demented patients.