The section on Testing to Consider Prior to Performing an LP in DynaMed’s entry for lumbar puncture summarizes two prospective cohort studies and lists clinical findings such as age and aspects of clinical history and specific neurologic findings that were predictive of cranial lesions that contraindicated LP: age > 60 years, immunocompromised status, history of central nervous system disease, history of seizure within 1 week, abnormal level of consciousness, and focal findings on neurological exam.
Hasbun R, Abrahams J, Jekel J, Quagliarello VJ. Computed tomography of the head before lumbar puncture in adults with suspected meningitis. N Engl J Med. 2001 Dec 13;345(24):1727-33. 235 patients with suspected meningitis received CT before lumbar puncture. RESULTS: Abnormal CT in 24% of patients in the study; 5% had evidence of a mass effect. Factors associated with an abnormal head CT were age ≥ 60 years, immunocompromised, history of CNS disease, history of seizure within one week before presentation.
Gopal AK Cranial computed tomography before lumbar puncture: a prospective clinical evaluation. Arch Intern Med. 1999 Dec 13-27;159(22):2681-5. Of 113 patients with urgent circumstances necessitating CT, 15% of CTs showed new lesions but only 2.7% had lesions that contraindicated LP