The quality of evidence ratings, I-III, and the strength of recommendations (Type A-Type E) are defined at the end of the "Major Recommendations" field.
- Class I and Class II data in the anesthesiology literature and either Class I or Class II data in the neurology series show that smaller needle size is associated with reduced frequency of post-lumbar puncture headache (PLPHA) (Type A). The actual choice of needle size will be influenced by balancing other considerations, such as ease of use, the need to measure pressures, and the flow rate, with the desire to prevent PLPHA.
- Class I data in the anesthesiology literature show that, when using a cutting needle, ensuring that the bevel direction is parallel to the dural fibers reduces the frequency of PLPHA. (Type A).
- Class I data using a noncutting needle show that replacement of the stylet before the needle is withdrawn is associated with lower frequency of PLPHA. (Type A).
- For spinal anesthesia, Class I data show that non-cutting needles reduce the frequency of PLPHA (Type A). However, for diagnostic lumbar punctures (LPs), the data are inconclusive.
- Class I and Class II data have not demonstrated that the duration of recumbency following a diagnostic lumbar puncture influences the occurrence of PLPHA.
- There is no evidence that the use of increased fluids prevents PLPHA.
Definitions of the classification of the recommendations (A, B, C, U) and classification of the evidence (Class I through Class IV) are provided at the end of the "Major Recommendations" field.
- New conclusion: Most studies in the anesthesiology literature, across several needle sizes, and now also one study providing Class I evidence in a patient population undergoing diagnostic lumbar punctures with a 22-gauge needle support the use of an atraumatic spinal needle to reduce the frequency of PLPHA (Type A).
Reaffirmation of a previous conclusion: Class I and Class II data in the anesthesiology and the neurology literature show that smaller needle size is associated with reduced frequency of PLPHA (Type A).
Quality of Evidence Ratings for Therapeutic Modalities
Class I. Evidence provided by one or more well-designed randomized controlled clinical trials.
Class II. Evidence provided by one or more well-designed clinical studies, such as case-control, cohort studies, etc.
Class III. Evidence provided by expert opinion, nonrandomized historical controls, or reports of one or more.
Strength of Recommendations
Type A. Strong positive recommendation based on Class I evidence, or based on overwhelming Class II evidence when circumstances preclude randomized clinical trials.
Type B. Positive recommendation based on Class II evidence.
Type C. Positive recommendation based on strong consensus of Class III evidence.
Type D. Negative recommendation based on inconclusive or conflicting Class II evidence.
Type E. Negative recommendation based on Class II or Class I evidence of ineffectiveness or lack of efficacy.
Classification of Evidence
Class I: Prospective, randomized, controlled clinical trial with masked outcome assessment in a representative population. The following are required:
- Primary outcome(s) is/are clearly defined.
- Exclusion/inclusion criteria are clearly defined.
- Adequate accounting for dropouts and crossovers with numbers sufficiently low to have minimal potential for bias.
- Relevant baseline characteristics are presented and substantially equivalent among treatment groups or there is appropriate statistical adjustment for differences.
Class II: Prospective matched group cohort study in a representative population with masked outcome assessment that meets A through D above OR a randomized, controlled trial in a representative population that lacks one criterion A through D.
Class III: All other controlled trials including well-defined natural history controls or patients serving as own controls in a representative population in which outcome assessment is independently assessed or independently derived by objective outcome measurement (objective outcome measurement is an outcome measure that is unlikely to be affected by an observer's (patient, treating physician, investigator) expectation or bias [e.g., blood tests, administrative outcome data]).
Class IV: Evidence from uncontrolled studies, case series, case reports, or expert opinion.
Classification of Recommendation
A = Established as effective, ineffective, or harmful for the given condition in the specified population. (Level A rating requires at least two consistent Class I studies.)
B = Probably effective, ineffective, or harmful for the given condition in the specified population. (Level B rating requires at least one Class I study or at least two consistent Class II studies.)
C = Possibly effective, ineffective, or harmful for the given condition in the specified population. (Level C rating requires at least one Class II study or two consistent Class III studies.)
U = Data inadequate or conflicting; given current knowledge, treatment is unproven.