Tubular discectomy for the treatment of lumbar disc herniation : new standard or transient fashion? : Results of a double-blind randomised controlled trial
Arts, M.P.
Citation
Arts, M. P. (2010, September 23). Tubular discectomy for the treatment of lumbar disc herniation : new standard or transient fashion? : Results of a double-blind randomised controlled trial. Retrieved from https://hdl.handle.net/1887/15975
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Annapurna, Nepal
Chapter 1
Introduction
8 IChapter 1
Sciatica, or lumbosacral radicular syndrome, affects many people, the vast majority being caused by disc herniation with nerve root compression. Exact data on the incidence and prevalence are lacking. This is mainly caused by controversy in the definition of sciatica and variations in the populations studied. Generally, sciatica is defined as pain radiating to the leg below the knee following a dermatomal pattern. The estimated annual prevalence of disc- related sciatica in the general population is 2.2%,although reports in the literature range from 1.2%to 43%.1
The natural course of lumbar disc-related sciatica is favourable in most cases and 60 to 70 % of the patients recover with conservative treatments.2Patients are offered surgery whenever disabling radicular pain persists. However, the timing of surgery has been debated for a long time and large variations in surgery rates exist between and within countries.3This is mainly caused by the lack of clear evidence-based gUidelines. Very few randomised trials to evaluate the timing of surgery have been published since the classic study of Weber.4The outcome for patients treated with prolonged conservative care is similar to that of those treated with early surgery, although the rate of recovery is slower.5-7Based on these results, the present decision- making process for patients with herniated disc-related sciatica is based on the preferences of patients and surgeons, instead of the duration of complaints.
EARLY DAYS OF SCIATICA
The Greek physician Hippocrates (460-370 BC) was probably the first to describe sciatica and low-back pain (Figure 1). Any complaint referable to the general area of the hip was considered to be sciatica at that time. He also mentioned that spinal injury is related to limb paralysis and observed that paralysis is always on the same side as the lesion of the spinal cord. Moreover, Hippocrates laid the foundation for traction beds to counteract the development of kyphosis and relieve patients of their pain.s For these reasons, Hippocrates is considered by some authors as "the father of spine surgery".9 Caelius Aurelianus made the first clinical description of sciatica in the 4th century AD. The syndrome was characterised by a strong, severe pain emanating from the lower back and radiating into the buttocks, perineum, popliteal fossa, calf, foot, and toes.lO The ancient Greek and Roman physicians were unable to separate tendons from ligaments and nerves, so all of these anatomical structures were designated by the collective term "nerves".9 Andreas Vesalius (1514-1564) was the first to describe the intervertebral disc: he depicted the spinal column and the intervertebral disc in his "De Humani
Introduction
I
9Corporis Fabrica" (1543). The Italian physician Domenico Cotugno (1736-1822), credited with the discovery of cerebrospinal fluid, also described the clinical manifestation of sciatica. After his publication "De ischiade nervosa commentarius" in 1764, sciatica was known as Cotugno's disease for many years.u In the following years, new facts about the spine were limited since localisation of neurological complaints was not a primary concern until the 18thcentury.
Chapter
1
Figure 1: "Get knowledge of the spine, for this is the requisite for many diseases"
A DREAM CAME TRUE
As late as 1799, Sir Charles Bell's younger brother John Bell (1763-1820) reported that "cutting into a vertebra is a dream" and it was Sir Percivall Port (1714-1788) who performed the first surgery on a patient with a spinal infection in Great Brirtain.8 In 1829, Alban Gilbin Smith was the first American surgeon to perform a laminectomy on a patient who developed progressive paraparesis after a fall from a horse 2 years before.12 In 1857, traumatic rupture of the intervertebral disc was described by Rudolf Virchow (1821-1902); it became
10
I
Chapter 1known as "Virchow's tumor".13 The German neurosurgeon Fedor Krause (1857-1937) and his neurologist colleague Hermann Oppenheim (1858-1919) reported the first successful removal of a ruptured herniated disc in 1909. The dura was widely exposed and the so-called
"enchondroma" was resected transdurally.14 The historical publication on lumbar disc surgery, however, was presented by the neurosurgeon William Mixter (1880-1958) and his orthopaedic colleague Joseph Barr (1901-1964) in 1934.15 This report greatly influenced the attitude ofthe medical profession toward the aetiology and treatment of sciatica.
FROM LARGE TO SMALL
After the publication of Mixter and Barr, lumbar disc surgery became one of the most frequently performed surgical procedures worldwide. The technique described by Mixter and Barr involved extensive removal of the lamina with transdural excision of the herniated disc. The rationale for opening the dura was twofold: removal of the irritating fluid lipiodol which was injected intrathecally for imaging purposes, and the hypothesis that paramedian disc protrusions could not be removed without opening the dura (Figure 2).15 Love first introduced extradural removal of the lumbar herniated disc by retraction of the dura medially and incision of the protruding disc (Figure 3).16 It was not until the late 1960's that less invasive approaches were introduced, aiming at shorter hospitalisation, less morbidity, and faster recovery. With the introduction of the microscope, Yasargil and Caspar launched the unilateral microdiscectomy, which is presently regarded as the golden standard.l7' 18 Williams popularised microdiscectomy in the United States in 1978. He operated on Las Vegas showgirls and his series of patients reported minimal scars and faster return to work. 19
A shift toward minimally invasive approaches to the spine occurred. The rationale behind minimally invasive spine surgery is less tissue damage, shorter hospitalisation, and faster recovery while achieving a good clinical outcome comparable with that of open conventional surgery. Minimally invasive spine surgery has adopted several techniques from other fields and has been influenced by endoscopy, biochemical advances, lasers, and image guidance systems. In 1963, Smith et al. were the first to inject chymopapaine into a herniated disc for the purpose of hydrolysing the mucoprotein. 20, 21 Although it has been applied for more than 30 years, meta-analyses showed that chemonucleolysis is more effective than placebo, but less effective than surgical nerve root decompression.22In 1975, Hijikata performed percutaneous nucleotomy by inserting a 7-mm tube under local anaesthesia with partial resection of the
Introduction 111
disc materiat.23Kambin24reported the first results of arthroscopic discectomy by means of a cannula and forceps, later refined by Maroon and Onik25who chose a guillotine-like probe into the disc. Choi and Ascher reviewed the first results of percutaneous laser disc decompression aimed at decreasing intradisc pressure with subsequent nerve root relief.26
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Figure 2: Transdural removal of "enchondroma"
of the intervertebral disc published byMixter and Barr inNEJMin1934.
In 1997, Foley and Smith replaced subperiosteal muscle dissection of the open microdiscectomy with the transmuscular muscle splitting technique of microendoscopic discectomy.27Because of the unfamiliarity of most neurosurgeons with endoscopic techniques, Smith and Foley introduced a modified set of tubular dilators and retractors used specifically for the microscope. The transmuscular approach by this so-called METRx system (Medtronic) is the subject of this thesis.
The worldwide introduction of minimally invasive spine surgery has been influenced by patients' preferences, physicians' preferences, and marketing tools of the industry. Therefore, every new surgical procedure should be compared with the golden standard by randomised controlled (cost)-effectiveness trials, prior to implementation of the new technique on a large
12
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Chapter 1scale. In case of tubular discectomy for the treatment of lumbar disc-related sciatica, such a trial has not been performed before.
Figure3: Extradural removal of the herniated disc described by Love and Camp in JBJS in 1937.
OBJECTIVE AND OUTLINE OF THIS THESIS
The main objective of this thesis is to compare randomly the (cost)-effectiveness of tubular discectomy versus conventional microdiscectomy during the first two years after surgery, i.e. the Sciatica-MED trial. At the start of this research project, no randomised controlled trials on tubular discectomy versus microdiscectomy has been published in the literature.
However, tubular discectomy was already part of the dai Iy practice in some neurosurgical and orthopaedic clinics in the Netherlands. In chapter 2 a national survey of Dutch spine surgeons is presented about the usual care of patients with herniated lumbar discs. Surgeons' expectations of different conventional and minimally invasive lumbar disc surgery are presented. In chapter 3 the design of the Sciatica-MED trial is described, a double-blind randomised (cost)-effectiveness study to answer the question of whether tubular discectomy
Introduction
113
is more (cost)-effective than conventional microdiscectomy. The one-year clinical results are presented in chapter 4, followed by comments on our publication. Before implementation of a new surgical technique is considered, the clinical results should be weighted against the total direct and indirect costs of both procedures. The results of this cost benefit analysis are described in chapter 5.
Certain anamnestic, neurological, and radiological variables might facilitate decision- making between tubular discectomy and conventional microdiscectomy for the treatment of patients with herniated disc-related sciatica. A subgroup analysis of predefined variables and their interaction with the treatment strategy is the main subject of chapter 6.
Chapter 7 describes the two-year clinical results of this trial.
Muscle trauma is quantified by the release of the enzyme creatine phosphokinase (CPK) in serum. Although the concept of minimally invasive spine surgery is reduced muscle injury, a relationship between limited muscle injury and reduced postoperative CPK is controversial.
Chapter 8 describes the relationship between postoperative CPK and various spinal and non- spinal procedures. In chapter 9, postoperative CPK is documented in patients treated with tubular discectomy or conventional microdiscectomy. Moreover, the postoperative volume of the multifidus muscle is measured and multifidus muscle atrophy is graded on magnetic resonance images (MRI). A synthesis and general discussion about the results are given in chapter 10. Summary and conclusions are presented in chapter 11.
Chapter
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14
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Chapter 1REFERENCES
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