Letter to the Editor: Pneumocephalus: Is the needle size significant?

Discussion. Pneumocephalus is defined by two mechanisms: a ball-valve and an inverted bottle concept.1 The ball-valve type implies positive pressure events, such as coughing or valsalva maneuvers, that prevent air escape. Tension pneumocephalus is included in this mechanism, causing a parenchymal mass effect. The inverted bottle theory includes a negative intracranial pressure gradient following cerebrospinal fluid drainage, relieved by air influx. A small pneumocephalus is usually sealed by blood clots or granulation, allowing spontaneous reabsorption and resolution.[1] Otherwise, the lateral positioning of a patient during spinal tap might create a lower intrathecal pressure with air being allowed into the subarachnoid space. Pneumocephalus also can develop when a stylet is reinserted into the needle before needle retraction, usually performed to minimize post-dural-puncture headache.[6] Pneumocephalus can be avoided by performing the LP in a sitting position, monitoring the amount of fluid drainage, carefully replacing the stylet to make sure the needle does not contain air, and instructing patients to briefly hold their breath and prevent making sudden movements during the procedure.[3] It is also important to consider needle size during a spinal tap. A smaller gauge makes a smaller dural perforation, causing less damage compared to larger ones; that also prevents cerebrospinal fluid leakage.[7,8] There is an inverse correlation between the needle gauge and post-dural-pun...
Source: Innovations in Clinical Neuroscience - Category: Neuroscience Authors: Tags: Assessment Tools CNS Infections Current Issue Letters to the Editor Neurologic Systems and Symptoms Neurology Stroke Traumatic Brain Injury epidural needle size Pneumocephalus spinal tap Source Type: research