Drury begins this paper with an introduction of how the superior cluneal nerves can be damaged and in what way it can cause disability and pain.
Seven cases are reported, where a local anaesthetic infiltration of the superior cluneal nerves alleviated the residual symptoms and disability of the patients after lumbar surgery. Drury also emphasises that a permanent relief can be achieved by resection of these nerves.
It is worth recalling that all patients involved in this study have been relieved from their symptoms which had been attributed to the cluneal nerve damage. The author declares that the sensory loss over the distribution of the resected nerve has not been a source of complaint.
Notes on the article of:
Clinical evaluation of damage to the Superior Cluneal Nerves
Drury, Bernard J.
American Journal of Orthopedic Surgery 1968; 10(4): 102-106
Drury’s Introduction: Causes of the Superior Cluneal Nerves Damage
- Drury states that many patients continue experiencing low back and extremity complaints despite that they have been adequate surgical treatment.
- In past examinations he observed that injury to the superior cluneal nerve (SCN) can be quite disabling, considering that these nerves can be easily damaged while the posterior iliac crest is exposed for removal of the bone.
- Drury claims that many surgeons no have been aware of the SCNs during the iliac crest exposure, even they ignore the existence of cluneal nerves. Therefore, it is one of the causes of continued pain and disability after lumbosacral surgery.
- Furthermore, the author suggests that the damage to the SCNs should be considered whenever bone has been removed from the posterior iliac crest and symptoms persist, this recognition will prevent unnecessary re-exploration of the lumbar spine.
Anatomy notes of Superior Cluneal Nerves
- According to Drury, the superior cluneal nerves (SCNs) are composed of lateral branches of the posterior primary divisions of the upper three lumbar nerves which exit through the lumbosacral fascia at the lateral origin of the sacrospinalis musculature and cross over the dorsal part of the posterior iliac crest, (Figure 1).
- A few of the SCN branches may proceed downward and lateralward as far as the greater trochanter.
Drury’s Clinical Findings related to the Superior Cluneals Nerves
- Drury highlights that when the SCNs are entrapped in scar or have been damaged, pain and paresthesias might be experienced over this distribution. Due to reflex distribution, pain might be experienced lower in the thigh and calf.
- The reflex distribution is described by Drury as a spinal root irritation but definite sensory loss, muscle weakness or reflex change do not occur when the discomfort has been of a reflex nature.
- Tenderness to palpation over the posterior iliac crest or just superior to it is revealed by a physical examination. If the nerves have been damaged there might be a loss of sensation in the middle and upper part of the buttock.
- Drury mentions that surgeons usually remove the iliac bone from the opposite side of nerve root exploration. Thus, complaints at the site of the iliac exploration should be considered as due to damage to the SCNs.
Infiltration of the superior cluneal nerves
Drury explains how the superior cluneal nerves damaged are the cause of disability, a proof can be made by infiltrating the distal course of the nerves as they exit from the lumbosacral fascia.
The infiltration process is illustrated in Figure 2, where the common site of the exit is usually within 1 to 2 inches from the superior middle aspect of the posterior iliac crest in line with the lateral side of the sacrospinalis musculature. The infiltration of this area with an anaesthetic of choice to the depth of the lumbosacral fascia readily allows blockage of these nerves.
The author mentions that temporary relief will be experienced at the iliac crest and buttock if these nerves are the cause of disability.
Surgical technique for Superior Cluneal Nerves resection
Drury states that permanent relief can be achieved by resection of the SCN nerves, also he is certain that a local anaesthetic would allow adequate exposure.
The author suggests that the exposure of the superior cluneal nerves is best through an incision parallel an in line with the lateral border of the sacrospinalis musculature extending 4 to 6 inches above and 2 inches below the posterior iliac crest.
As was showed in the previous section the SCNs exit as one of several branches from the lumbosacral fascia about 1.5 to 2 inches above the posterior iliac crest, therefore, it is important to find this site of exit and then trace the branches distally in order to find which branch is involved in scar tissue or has been damaged. The involved branch should be resected for about three inches.
Drury’s Case reports related to the superior cluneal nerves
In this section, Drury evaluates the damage of the superior cluneal nerves in seven patients as described below:
CASE 1. A 50-year-old salesman, who in 1962 had a hemilaminectomy at the right lumbosacral level with the removal of a protruded disc and a spinal fusion from L-4 to the sacrum.
Three years after his spinal surgery, he complained of persistent pain in the left buttock and low back, after an anaesthetic block of the SCN nerves he was considerably relieved. Later, a superior cluneal nerve was found embedded in scar tissue at the left iliac crest and was resected. The patient claimed that his preoperative discomfort in the back and left buttock was completely relieved.
CASE 2. A 47-year-old housewife, had a laminectomy at the L 4-5 level in 1954 with excellent recovery.
- In September of 1963, she developed severe low back pain, subsequently, a defect on the left at the L 4-5 level was detected and a hemilaminectomy was performed in this area followed by a spinal fusion in December of 1963.
- 15 months following this surgery she was examined because of discomfort in the posterior left buttock and thigh, she presented tenderness over the distribution of the left superior cluneal nerve, an infiltration of these nerves completely relieved her from discomfort.
- In 1965 these nerves were explored and found to be bound in scar tissue, one year later she stated that her discomfort in the left buttock and low back had disappeared.
CASE 3. A 42-year-old housewife, had a laminectomy and spinal fusion at the lower three lumbar levels in 1959 because of back and bilateral lower leg discomfort. Bone had been removed from the left posterior iliac crest.
- After that, she had relief from her back complaints for one year. However, in June of 1965 she was examined for recurring episodes of pain in the left buttock region and a transverse scar was found at the lumbosacral level.
- Then the area of the left cluneal nerves was infiltrated with an anaesthetic and this greatly relieved the patient’s pain.
- Moreover, one SCN branch was found to run distally into the old iliac donor site and was bounded in scar tissue, a three inches segment of the nerve was removed. On postoperative examination the patient stated that all of the left buttock and thigh pain had disappeared.
CASE 4. A 27-year-old mechanic, injured his back. A laminectomy was performed in February of 1965, and this followed by a spinal fusion from L-4 to the sacrum with a bone graft removed from the right iliac crest.
- Afterward his surgery he complained of discomfort in the right buttock and shooting pain. Then the region of the right posterior iliac crest was infiltrated with anaesthetic and the discomfort into the right buttock disappeared.
- Later in September of 1965, two branches of superior cluneal nerve were found to be bound in scar at the right posterior iliac crest, these were resected for three inches. After this procedure, the pain in the right iliac crest had been relieved.
CASE 5. A 32-year-old white female. She had a complicated history of back and lower extremity involvement: laminectomy and lumbosacral fusion in 1948, an operative procedure to repair a pseudoarthrosis in 1956, and a hemilaminectomy at the right L 4-5 and a fusion extended from L4 to the sacrum in 1964.
- The patient was examined in 1965 because of pain in the right buttock and low back, the area over the posterior aspect of the right iliac crest was found to be very tender to palpitation. So, this area was infiltrated with anaesthetic and she was greatly relieved from complaints into the right buttock.
- Then, the right superior cluneal nerves were exposed and one of these branches was found to be bound in a scar tissue. Following resection of this nerve she was completely relieved of from discomfort in the right buttock.
CASE 6. A 42-year-old man, stated that a laminectomy had been performed in 1963 with excision of the lumbosacral disc.
- In 1965, because of continued disability the L 4-5 disc was removed and a spinal fusion was performed from L-4 to the sacrum. After this surgery, the patient complained of discomfort in the low back and subsequent to this developed discomfort over the left posterior iliac crest. Thus, this area was infiltrated with anaesthetic which relieved his discomfort.
- The left iliac crest was exposed at the surgery and three branches of the SCNs were identified and noted to be directly involved in scar at the left ilium, these nerves were resected and consequently, he was free of discomfort in the left buttock.
CASE 7. A 48-year-old laborer, injured his back in June of 1963. In that time, a pseudoarthrosis was found due to a previous fusion in 1944. In September of 1963, the lower lumbar spine was explored and iliac bone was removed from the left posterior iliac crest.
- After his surgery, he complained of discomfort in the left buttock, which was aggravated by lying on the left side or sitting for prolonged periods.
- In 1965, marked tenderness was found over the distribution of the left superior cluneal nerves. Then, an infiltrationof this area with an anaesthetic was performed and the burning in the left buttock had disappeared.
- Because the complaints returned, he was taken to surgery where a portion of the SCN was found to run deep into thick scar tissue about the left posterior iliac crest. This branch was resected for three inches.
- Subsequently, the patient stated that the discomfort in the left buttock had disappeared. Moreover, a physical examination revealed an area of decreased sensation two by two inches just lateral and below the left posterior iliac crest.
The most important facts about this paper are summarized by Drury:
- He emphasises that the damage to the superior cluneal nerves can cause disability and pain.
- These nerves might be damaged during an exposure to the posterior iliac crest for the removal of bone.
- He highlights that a local anaesthetic infiltration of the superior cluneal nerves as they exit through the lumbosacral fascia alleviates symptoms and disability which are due to this irritation.
- Subsequently, he states that resection of these nerves has relieved patients from their previous incapacities according to the results of the seven cases reported in this paper.
Published by Marta Cañis Parera in February 2020 (with the collaboration from Mauricio Valarezo)