Fibrous structures in the subarachnoid space: a study with spinaloscopy in autopsy subjects.

The lumbar and lower thoracic subarachnoid space of 26 human autopsy subjects was studied using rigid endoscopy, spinaloscopy. Fibrous attachments were found between nerve roots and/or nerve roots and the arachnoid membrane at least at one spinal level in 16 subjects. The appearance and density of the structures varied, and caused restriction of nerve root mobility in nine subjects. In three of them, the impeded mobility prevented the nerve root from yielding to the contact and pressure exerted either by the tip of the endoscope or by a spinal needle introduced into the subarachnoid space. In another three subjects, a distinct membranous structure was identified in the posterior midline of the subarachnoid space in the lower thoracic and upper lumbar regions. These findings may possibly be associated with the variation in the extent of subarachnoid block and to the development of isolated nerve root trauma in connection with this procedure.

Advantages of the paramedian approach for lumbar epidural analgesia with catheter technique. A clinical comparison between midline and paramedian approaches.

Forty-nine patients, scheduled for transurethral resection of the prostate or a bladder neoplasm on 50 occasions, were studied. The patients were randomly allocated to one of the two methods of puncture, midline or paramedian. Technical difficulties and the occurrence of complications were recorded. The extent of sensory and motor blockade was also compared. The paramedian approach was associated with a lower frequency of technical problems compared to the midline approach. Statistically significant differences were demonstrated between the two techniques for the following factors: repeated attempts at needle insertion; difficulty in identification of the epidural space; resistance to introduction of the catheter; resistance to injection through the epidural catheter; and the production of paraesthesiae (nine patients in the midline group compared to only one patient in the paramedian group, p less than 0.01). The catheter entered a vessel at first in two patients in each group. No significant differences were demonstrated between the groups in the extent of sensory and motor blockade. The study supports the view that the paramedian approach has technical advantages over the midline approach for lumbar epidural analgesia with catheter technique.

The lumbar epidural space in patients examined with epiduroscopy.

Percutaneous epiduroscopy was performed in 10 patients with the aim of comparing the lumbar epidural space of the patients with the findings made earlier in autopsy subjects. The patients were scheduled for partial laminectomy for a herniated lumbar disc. A complete examination was possible in eight subjects. The extent of view was very limited. The epidural space opened up only temporarily as air was injected. The dura mater lay very close to the dorsal aspect of the epidural space and was attached to the flaval ligaments by a dorsomedian connective tissue band. The band was identified in all eight subjects and was found to cause a dorsal fold in the dura mater. An epidural catheter was introduced 2-5 cm into the space by midline puncture in four patients and by the paramedian approach in the other four. The catheter was visualized in two patients only when the paramedian approach was used. None of the midline catheters could be seen in the space. In 2 of the 10 subjects a moderate bleeding impaired the view and made complete examination impossible. Smaller bleeding occurred in three other subjects. The partial laminectomy performed one to two interspaces caudad to the level of endoscopy did not reveal any evidence of epidural bleeding in any subject. The postoperative course of all patients was uneventful.

Technical advantages of the paramedian approach for lumbar epidural puncture and catheter introduction. A study using epiduroscopy in autopsy subjects.

The lumbar epidural space of 14 autopsy subjects was examined by epiduroscopy. The aim was to compare the midline and paramedian approaches of locating the space, the estimated risk of accidental dural puncture, the course taken by the epidural catheter after introduction and with special attention to the influence of the dorsomedian connective tissue band. The paramedian needle passed a greater distance within the epidural space before contact with the dura mater and demonstrated a low risk of accidental dural puncture. The catheter passed by the paramedian approach did not cause any tenting of the dura and took a straight cephalad direction in all 14 cases. The midline catheter caused tenting of the dura in all 14 cases and the direction of travel was variable. Differences were statistically significant. Influence of the dorsomedian connective tissue band was greatest on the behaviour of the midline needle and catheter.

The lumbar subdural extraarachnoid space of humans: an anatomical study using spinaloscopy in autopsy cases.

The lumbar subdural extraarachnoid space was examined by spinaloscopy in 15 autopsy subjects. Special attention was paid to the ease with which the space opened up and also to the extent of view achieved. In ten cases the space opened up with ease, in four cases with difficulty, and in one case it was not possible to establish the subdural space at all. The bevel of an 18-gauge Tuohy needle introduced into the subdural space could be visualized in eight of 13 cases. An epidural catheter was then passed through the Tuohy needle into the subdural space in eight cases and was visualized in six of them. Although care must be exercised in drawing conclusions for clinical epidural anesthesia from autopsy cases, this study confirms the possibility of placing both the bevel of a Tuohy needle and an epidural catheter in the subdural space. The results reemphasize the need for caution suggested by other reports regarding the possibility of subdural puncture in epidural anesthesia and subsequent injection of anesthetic solution into the subdural space.