Difficult Lumbar Puncture: Pitfalls and Tips from the Trenches

Adult patient, BMI 49, with bowel incarceration requiring an operation, now with altered mental status. LP was requested to exclude meningitis. The patient is in the right lateral decubitus position so that the respiratory technologist can control the tracheostomy and airway. Note the tip of the needle in the mid-spinal canal.

Adult patient with multiple epidural lumbar steroid injections, now recalcitrant to more injections. The patient experienced severe pain during an attempted LP. Note severe arachnoiditis. A, T2 sagittal MR image shows marked clumping of the cauda equina in the central thecal sac, but it also adhered to the posterior dural wall. The conus appears irregular, also from arachnoiditis. B, T1 sagittal, postgadolinium image with fat saturation shows diffuse enhancement of the nerve roots and meninges. Arachnoiditis does not always enhance. Because meningitis could have a similar appearance, CSF must be obtained to exclude infection, despite the arachnoiditis.

Adult female patients with morbid obesity and large fat shelf on the lower lumbar back. A, Sagittal reformation from a noncontrast abdominal and pelvis CT shows the deformity of the back, even with the patient supine. B, Sagittal T2 MR image in another patient with marked subcutaneous fat in the lower thoracic and lumbar back. Note an abrupt increase in fat thickness at the L3 level, which makes LP difficult.

A man with epidural lipomatosis. T1 sagittal MR image shows high-signal-intensity fat around the thecal sac, with marked narrowing at L5.

Spot fluoroscopic image showing a 23-ga needle near the lamina for deep anesthesia. It is critical that the lidocaine not be injected into the spinal canal or thecal sac. We never use the anesthesia needle in the thecal sac.

Cross-table lateral film after failure to obtain CSF, thought to be a dry tap. Note the LP approach at the L4–5 disc space and the needle extended through the disc into the retroperitoneum. At this point, the stylet was removed and no blood was returned. The needle was withdrawn at 5-mm increments, each time checking for arterial or venous blood return. There were no complications, but the diagnostic LP was cancelled until the following day.

Fluoroscopic spot films obtained during LP, showing parallax artifacts. A, Note that on this image, the needle is not centered and the tip appears to abut the inferior spinous process. B, The same procedure with no needle adjustment, but now the tip is centered in the image. CSF flow was normal.

Bubble technique to avoid sucking nerve roots into the spinal needle. The short tubing is literally lying on the LP needle hub so that there is no manipulation of the needle. Both air and CSF fill the tubing and the syringe. With this technique, we have never had nerve root pain reported, and CSF can be easily aspirated.

Lateral plain film in a patient with recurrent back pain after bilateral pedicle screws at nearly every level. Note dystrophic ossification from a fusion graft. In a patient with extensive postoperative changes, cross-sectional imaging should be obtained to determine whether there is a patent trajectory for the LP.