BACKGROUND

Severe complications after spinal anesthesia are rare, in a large prospective series (40640 spinal anesthetics)1 only 6 patients out of 10000 reported neurologic injury lasting more than 3 months, in most cases it was associated with paresthesia during puncture or pain during injection, and it had the same topography as the parethesiae associated. The cause for theses neurologic symptoms remains undetermined, but possible explanations include direct neurotoxicity of local anesthetic, patient characteristics, muscle spasm and needle trauma.

We introduce a small modification in the spinal puncture technique to minimize needle trauma, we propose to advance the standard pencil-point needle without the stylet filled with a hanging drop of normal saline solution. Once the tip reaches the epidural space the drop will be aspirated into the needle giving you an indication of the proximity to the dura. We believe this modification will result in a needle tip farther away from the nerve roots and less likely to damage these nerves.

METHODS

Patients (n=20) scheduled for surgery under spinal anesthesia were observed during spinal needle insertion.  The technique was performed under sterile conditions using a 25 G Whitacre needle, after the needle passed the first 2 centimetres, the stylet was removed and the needle was filled with normal saline until a drop of saline was observed hanging from the hub. The needle was advanced until either suction of the drop or flow of cerebrospintal fluid (CSF) was observed. When suction was observed, the needle was further advanced until the flow of CSF

RESULTS

Aspiration of the normal saline was observed in 18/20 of patients, no complications were recorded.

DISCUSSION

An overwhelming majority of our cases showed a positive result to our technique and we found no paresthesiae. It is a small study with no statistical significance, however it has the potential of avoiding long-term complications and we believe it deserves further consideration.

Intradural puncture using a hanging drop technique