About 30% of lumbar punctures are complicated by the lumbar puncture syndrome the main symptom of which is a characteristically posture-dependent headache (the so-called "spinal headache"), sometimes accompanied by nausea, vomiting and stiff neck. The syndrome usually begins in the days which follow lumbar puncture and subsides within 10 days. The most common pathogenetic theory is that perforation of the dura mater results in CSF leakage responsible for a fall in intrathecal pressure. Treatment of the lumbar puncture syndrome consists of rest in supine position and copious hydration, usually by the oral route. The epidural blood patch technique is seldom used. Prevention relies entirely on the use of small calibre lumbar puncture needles; keeping the patient lying supine after the puncture is a classical recommendation, but its preventive value has not yet been fully demonstrated.