Purpose Percutaneous lumbar puncture (LP) is used to access the subarachnoid space (SAS) for cerebrospinal fluid (CSF) withdrawal, injection of drugs or imaging agents, or monitoring CSF pressure changes during lumbar infusion studies. Patients requiring LPs can be challenging, and imaging guidance for SAS access has grown in demand and use, often leading to neuroradiologists being the primary providers of this procedure. However, a fluoroscopic LP may be impossible for several anatomical or logistical reasons. We provide a pictorial and educational review of 8 alternative new and old techniques to aid neuroradiologists in percutaneous access of the SAS for those uncommon instances when standard LPs fail or are not possible. Methods We review and illustrate the techniques and complications of 8 alternative procedures to insert a spinal needle into the SAS. We present these by location, from cephalad to cauda along the spinal axis. Findings 1) Cisternal tap (suboccipital puncture) is now extremely rare. A spinal needle is inserted midline between inion and C2 spinous process, and directed superiorly through the atlanto-occipital membrane into cisterna magna under lateral fluoroscopy. Two potential major complications are SAH and medullary puncture. 2) Fluoroscopic lateral C1-C2 puncture for SAS access in the dorsal third of the spinal canal, to avoid a possible more ventral fenestrated vertebral artery or anomalous low PICA. 3) Posterior thoracic SAS puncture between T9-T11, as per spinal anesthesia using a 27G needle; several drops (each is 60 microL) of CSF may be sufficient for lab analysis. 4) High LP between L1-L3 in the lateral decubitous position helps avoid the gravity-displaced conus. 5) Transforaminal fluoroscopic or CT-guided LP by targeting the mid posterior aspect of the vertebral foramen appears safe in preliminary experiences to date. 6) Transosseous translaminar LP is possible through a spinal needle coaxially threaded in a bone biopsy system in patients with fused posterior elements after surgery or ankylosing spondylitis. 7) Transforaminal-sacral SAS puncture through S1 or S2 foramen, as per spinal anesthesia. 8) Trans-sacral hiatus approach to the sacral cistern has also been described when the sacrum is sufficiently straight. Summary Neuroradiologists should be familiar with all possible image-guided percutaneous techniques to access the SAS. This presentation will aid in understanding all alternatives when standard LPs are contraindicated, difficult, or fail.
No datasets are available for this submission.