Accidental Subdural Catheterization: Radiological Evidence of a Possible Mechanism for Spinal Cord Damage

Abstract

We describe the inadvertent subdural insertion of a lumbar extradural catheter in a primiparous woman in labour. A small quantity of local anaesthetic resulted in extensive motor and sensory block. Computed tomography performed after contrast injection demonstrated unequivocally that the catheter was in the subdural space. The catheter and injected fluid produced considerable displacement of the arachnoid within the thecal sac. We postulate that this could result in arterial compression or direct damage to the spinal nerve roots. Such a mechanism might explain some of the cases of permanent neurological damage associated with extradural analgesia.

Subdural or epidural?

“…The position of the catheter in the subdural space has been confirmed by X rays using contrast [I-3,5, 7,8], as well as computerised axial tomographic scan [9]. In this case we used an MRI scan to confirm that the catheter had been in the subdural space.…”

“…Certainly a high level of suspicion should exist for subdural placement of the epidural catheter in any cases which, despite a negative aspiration for cerebral spinal fluid, behave in a bizarre manner. Because the volume of the subdural space is small, subdural fluid collection may lead to compression of the subarachnoid contents and account for the rare cases of permanent neurological damage associated with extradural analgesia [9].…”

Accidental subdural catheterization suspected on administration of a test dose of lidocaine and successfully managed by a small dose of dibucaine

“…Since then, a number of reports have been published on subdural block [2][3][4][5][6][7][8][9][10][11][12][13][14], and a variety of courses and mechanisms have been discussed. In almost all of these reported cases, subdural anesthesia was recognized by the appearance of unexpectedly extensive blockade after administration of the usual dose of a local anesthetic suitable for epidural block.…”

“…From an anatomical viewpoint, an aspiration test cannot be expected to detect all cases of accidental subdural catheterization. In previous case reports, subdural injections of local anesthetics were recognized after applying relatively large doses of anesthetics because of slow onset [2][3][4][5][6][7][8][9][10][11][12][13][14]. We report a case in which the anesthetist was alerted to the possibility of accidental subdural catheterization by the injection of 3 ml of 1% lidocaine as a test dose without inducing significant adverse cardiovascular responses.…”

Sekundäre subdurale Fehllage eines Epiduralkatheters

“…Unerkannt kann die Katheterfehllage für den Patienten lebensbedrohlich werden [5], außerdem ist die Separation der Arachnoidea von der Dura möglicherweise für einige Fälle der bleibenden neurologischen Schäden nach Periduralanästhesien verantwortlich [13]. Die klinische Diagnose der Komplikation ist schwierig, eine endgül-tige Beurteilung ist meist nur mit Hilfe einer Röntgenuntersuchung möglich.…”