Thermocoagulation of the Medial Branch of the Dorsal Branch of the Lumbal Spinal Nerve: Flouroscopy Versus CT.

Objective: For radiofrequency neurotomy of the medial branch of the lumbar dorsal rami, physicians use techniques guided either by fluoroscopy or computerized tomography (CT), and advocate for their respective techniques. Crucial to the choice of technique is how well each can capture the target nerve. The present study was, therefore, undertaken to assess in cadavers the accuracy of fluoroscopic-guided and CT-guided techniques. Design: In10 cadavers preserved with Thiel's method, electrodes with 10mm active tips were placed in supine position on the right using a fluoroscopic-guided technique, and on the left using a CT-guided technique. Using a special dissection approach, the relationship between the target nerve and the tip of the electrode was revealed. The displacement between electrode and the nerve, and the extent to which the electrode was parallel to the nerve, were measured with callipers. Results: Under fluoroscopy guidance, electrodes were placed accurately beside the nerve, and were parallel to it for 9 ±1.9 mm. In only two cases did the electrode pass too deeply. Under CT guidance, electrodes often failed to reach the nerve, but when they did they were parallel to it for only 3.2 ± 3.2 mm. In seven cases, the electrode passed too deeply beyond the target nerve. Conclusion: The fluoroscopy-guided technique can be relied upon to achieve optimal placement of electrodes on the lumbar medial branches. The CT-guided technique fails to do so, and should not be used in practice until a modified version has been developed and validated.

Susceptibility of the genitofemoral and lateral femoral cutaneous nerves to complications from lumbar sympathetic blocks: is there a morphological reason?

BACKGROUND: Interference with the function of the genitofemoral nerve (GFN) and lateral femoral cutaneous nerve (LFCN) represents a significant complication of lumbar sympathetic blocks (LSBs). The nerve topography of the lumbar sympathetic trunk (LST) was investigated to find a possible morphological reason for this. METHODS: A total of 118 cadavers embalmed by Thiel's method were investigated. The nerves were dissected from their innervation area to their paravertebral origins. Distances of the GFN and the LFCN to the LST were measured at levels L2/3, L3/4, and L4/5, which are the most common levels for LSB. RESULTS: Two hundred and thirteen sides were assessable for the GFN and 151 sides for the LFCN. In 186 cases, the whole GFN (in 20 cases, its femoral branch only) approached the medial margin of the psoas major (PM) and passed the LST laterally at the level of L3/4 and a distance of 0-28 mm (mean distance 8.5 mm; sd 6.7 mm) and ran dorsally between the PM and the vertebral body of L3, reaching the intervertebral foramen L2/3. In three cases, the GFN fused with the LFCN. In 55 cases, the GFN-LST distance was 0-13 mm at L4/5 and in 19 cases, 9-19 mm at L2/3. The LFCN approached the lateral margin of the PM and entered the intervertebral foramen at L2/3 in 141 cases. CONCLUSIONS: There is a higher risk of LSB affecting the GFN at L3/4 or L4/5 during neurolysis of the LST due to its topography. The LFCN rarely shows a strong relation to the LST and only when fused with the GFN.

Anatomical investigation of a new vertical obturator nerve block technique.

BACKGROUND: We evaluated a vertical obturator nerve block (VOB) using a single morphological landmark and no additional distance measurement or obligatory changes of the needle's direction. MATERIALS AND METHOD: A total of 88 cadavers (176 lower limbs), prepared using Thiel's embalming method, were examined. The index finger was placed lateral to the palpable pubic tubercle and the needle inserted laterally to the distal part of the fingernail at the tubercle's level and advanced strictly perpendicular to the table's surface. If bone contact was made, the needle was slightly turned to pass the bone distally. Colored latex (5 ml) was then injected. The injection depth was documented, then followed by dissection and nerve exposition. The real skin-nerve distance and the degree of difficulty in orientation and of palpation were measured. Additionally, the dissemination around the nerve or its branches and the intrapelvic spread were documented. RESULTS: The nerve was colored completely in 93.75%, partially in 1.71%, and not colored in 4.54% of cases. The mean injection depth was 3.9 cm (±0.7 SD) and real nerve depth was 3.8 cm (±0.69 SD). Bone contact necessitating the needle's redirection was found in 20 (11.4%) cases. Easy orientation and palpation of the tubercle was always found. In 40 cases, the latex spread via the obturator canal into the lesser pelvis. CONCLUSION: In this anatomical study, the VOB technique exhibits easy orientation without stimulation or ultrasound guidance. The nerve was located at a constant depth. The injection offered a high percentage of colored nerves.

The superficial palmar arch and median artery as an example of misleading results due to a small number of investigated specimens or the use of different classifications.

BACKGROUND: Small numbers of investigated specimens might lead to misinterpretations. Different classifications can change results dramatically. This is demonstrated by an investigation of the superficial palmar arch and the palmar median artery. MATERIALS AND METHODS: A total of 702 upper limbs were investigated. Data were collected during eight dissection courses for advanced medical students and one workshop of hand surgery (number of investigated limbs per course between 52 and 111). The variations of superficial palmar arches were documented according to the classification of Lippert and Pabst as well as the occurrence of a palmar median artery. The results of each course were compared among each other, to the total result and compared to allocation according Jaschtschinski's classification. RESULTS: In total, the results show complete arches in 52.15%. Incomplete arches with the ulnar artery supplying the thumb in 15.38%, reaching the index in 22.15% and the middle finger in 10.32%. Median arteries were documented in 4.5%. Individual course results varied concerning complete arches from 41.1% (37 out of 90) and 65% (35 out of 55), median arteries were found between 0 (0 of 69 hands) and 9.1% (5 of 55 hands). Classifying our total result with Jaschtschinski's classification there would have been complete arches in 67.8% (individual course result: 43.3-81.8%). CONCLUSIONS: Small numbers of investigated specimens can lead to confounding results. The classification used has to be precisely determined. Both classifications need to be known to interpret results correctly. A repetition of investigation might be performed to confirm results.

Topography of the lumbar sympathetic trunk in normal lumbar spines and spines with spondylophytes.

BACKGROUND: Degenerative processes of the lumbar spine may change the position of the sympathetic trunk which might cause failure of sympathetic blocks owing to inadequate distribution of local anaesthetic. METHODS: The retroperitoneal spaces of 56 cadavers [24 males and 32 females; 79 (10) yr] embalmed with Thiel's method were investigated by dissection. The course of the lumbar sympathetic trunk (LST) was documented from the diaphragmatic level to the linea terminalis. Topography of the large vessels and the psoas muscle was documented. In the case of spondylophytes, the location or direction of displacement of the trunk was regarded with special interest. RESULTS: The LST entered the retroperitoneal space at the level of the vertebral body of L2 in 70 of the 112 sides and showed the most consistent relationship with the medial margin of the psoas muscle at intervertebral disc level L2/3. On 11 spines with spondylophytes, the sympathetic trunk was dislocated to the most ventrolateral point of the spondylophyte in 12 cases, in six cases dorsolaterally, and in one case ventromedially. The more the sympathetic chain departed at the vertebral body level, the more the body developed a concavity by loss of height. CONCLUSIONS: Spondylophytes influenced the location of the LST and the distribution of the local anaesthetic. The local anaesthetic should wash around the spondylophyte to reach all possible locations of the chain. The medial margin of the psoas muscle was confirmed to be a consistent reference point at intervertebral disc level L2/3.