Microdiscectomy: a Positional Statement

Favorite Quote | The Conundrum of small HNP | Lumbar Disc Surgery | *Indications for surgery

Postacchini F, "Results of surgery compared with conservative management for lumbar disc herniations" Spine - 1996; 21(11):1383-1387

Italy 's most famous researcher and surgeon, Professor Franco Postacchini, MD gives and excellent tutorial on surgery versus conservative care.   He also summarizes some of the more famous and important studies of our time, and dishes out some tremendously wise 'words of wisdom'.   Here are some of the notes I took from his paper:

My Favorite Quote:

"Conservative management [of sciatica via symptomatic disc herniation] gives satisfactory results in a high proportion of patients with disc herniation in the course of a few months of treatment onset.   This is likely to occur particularly in patients with mild or moderate nerve root compression.   Surgical treatment is significantly faster in yielding a satisfactory resolution of symptoms.   The chances of a successful outcome are higher in patients with a marked nerve root compression, no or mild back pain, and a short duration of symptoms."

That really sums up what I've been studying for the last few months.   The severely symptomatic sciatic sufferers really seem to be the lucky ones IF they get a discectomy within 3 to 6 months.

Before we start we need to look at 'recovery periods' which Postacchini uses through his paper.   I was surprised to see that three to four years is only considered "medium term".

Five different phases of the 'post-treatment course' exist that correspond to different stages in "the evolution of the clinical result and the pathologic changes characterizing disc disease."

The Conundrum of the Disc Herniation:

Surgically speaking: "Patients with duration of symptoms longer than 1 year, particularly for those with a small disc protrusion or only a disc bulge, tended to have less favorable results (33).

In general "Immediately after surgery, results are satisfactory in more than 85% of patients, and usually the more severe the preoperative radicular pain, the more satisfactory is the result'.   Neurological defects usually improve, although mostly partially" (he's speaking of microdiscectomy and discectomy).

"Patients with a prolapsed or sequestered disc tend to recover better and faster than those with a disc protrusion, whatever the surgical method."

Surgical Outcome:  

Standard Discectomy - "In most series (research papers) analyzing patients submitted to standard discectomy, satisfactory results were obtained in approximately 80% of patients and poor outcomes (same or worse clinical condition) in approximately 5%." (34) "In most series, the proportion of good or excellent outcomes ranges from 80% to 90%, independently of the surgical technique (microdiscectomy or standard discectomy)."

"Most reported rates of satisfactory results after microdiscectomy range from 75% to 95%.   Several studies, however, did not find any significant differences between the results of standard discectomy and microdiscectomy at 1 to 2 year follow-up evaluation." (34, 35, 36)

All About Lumbar Disc Surgery:

Independent satisfactory outcome predictors for surgery :

1) Absence of back pain, 2) absence of a work-related injury, 3) radicular distribution of pain (follows a dermatome) extending into the foot, 4) leg pain on straight leg raising, and 5) reflex asymmetry. (34) "In one study, profession (profession personal), high level of education, and self-employment were found to lead to better outcomes, regardless of legal concerns or industrial insurance (workers compensation). (39)

Long Duration of pre-operative Pain : "Most studies analyzing the influence of the preoperative duration of pain found that patients with longstanding radicular pain (sciatica in a dermatomal pattern) tend to have less favorable results and a longer time off work than those with a shorter duration of symptoms." (37, 38)   The time limit after which the results tend to worsen is approximately 1 year."   "Elderly patients with a single-level disc herniation have similar results as those of middle-aged patients"

Surgery Results deteriorate with time:

"The results of surgery appear to deteriorate, although slightly, in the long and very long term regarding the short term.   Deterioration was found mostly to be because of recurrence or worsening of lower back pain."

There are two main hypotheses as two why: "One hypothesis is that deterioration is because of degenerative changes at the operated vertebral level.   The other is that degeneration of intervertebral discs or facet joints at different levels are responsible or exclusively responsible for worsening of the result."   Postacchini favors the latter.   He feels there is a "constitutional predisposition" (built in tendency to get disc degeneration) for other discs to degenerate and cause problems and not the surgery.

The 1970, Hakelius Outcome Study: (40) Other than the famous Weber study of 1983, Hakelius et al. was the first big long-term outcome study to assess the outcome of 417 patients, with confirmed disc herniation via myelogram, as compared to 166 surgically treated patient.   The results clears show that the surgical group got better faster and more completely as compared to the conservative group.   Although the study was not randomized, like the Weber study, it was a big one.

Results: At "long term" (5 years) 79% of the conservative group and 83% of the surgical group reported in:

Low back pain:   Satisfactory:   29% vs. 52% - conservative versus surgical.

Leg pain: 80% vs. 88% - conservative versus surgical.

INDICATIONS FOR SURGERY:

"Many herniations decrease in size or disappear with time, but many months or a few years may elapse before this occurs and the process may not even occur."   "Conversely, many reports indicate that patients with longstanding preoperative symptoms have fewer chances of obtaining a satisfactory result from surgery than those with a short duration of symptoms. Two needs should therefore be respected: 1) to avoid too protracted conservative treatments that may lengthen the time off from work and reduce the chances of a successful surgical treatment, and 2) to avoid surgery in patients with a herniated disc that may become asymptomatic or even disappear, within a few months of onset."  

1) Absolute indications for surgery: a) cauda equina syndrome, b) severe motor deficit resulting from a large extruded or migrated disc fragment, and c) intractable pain.   "In all other cases, the indication is relative."

2) Relative indications for surgery: a) duration of radicular symptoms, b) type and size of herniation, c) presence of nerve root canal or central spinal canal, stenosis, 4) quality and severity of symptoms.   Let's look at each category more closely:

a) Duration of radicular symptoms : "In my experience, the chances of resolution of symptoms with conservative care decrease progressively with increasing time (in terms of months rather than weeks)."

b) Type and size of herniation : Contained, extruded, or sequestered are the types.   "It is more likely that the symptoms decrease in severity or disappear when the herniation is contained and small [rather] than in the presence of a large migrated disc fragment."

c) Presence of nerve root canal, or central spinal canal, stenosis:   The chances of spontaneous resolution of symptoms are significantly higher in the presence of a normal sized spinal canal.

d) Quality and severity of symptoms:   "there is a greater indication for surgery in patients with severe, exclusively radicular pain, than in those with moderate low back and leg pain because in the former patients, the symptoms are less likely to resolve spontaneously and the results of surgery tends to be better.   The presence of a mild or moderate motor deficit does NOT necessarily affect the indication for surgery or conservative management because the chances of resolution of the deficit are similar with the two types of treatment."  

Final Words of Wisdom : "In all patients with a 'relative indication for surgery', surgery should be performed when no significant improvement has been obtained with conservative care.   The time that the latter should last is NOT well determined, but in most cases, it should not be less than 2-3 months.   Patients who do not improve considerably after this period have fewer chances to have an adequate resolution of symptoms with increasing time."

Approximately 15% of all patients who undergo conservative care for a lumbar disc herniation will be lost to surgery.   Approximately another 15% of the surgical patients will have to undergo yet another surgery.

Finally the author recommends 'microdiscectomy' over traditional discectomy.   "Numerous reports suggest that compared with standard discectomy, microdiscectomy decreases patient hospital stay and gives better results at short term, thus decreasing the postoperative sick leave time.   Based on these possible advantages, this procedure may be preferred to standard discectomy," although medium and long-term outcomes are about the same.

References:

33) Bush K, et al. (1992) "The natural history of sciatica associated with disc pathology: A prospective study with clinical and independent radiographic follow-up." Spine; 17:1205-12

34) Abramovitz JN, Neff SR, (1991) "Results of the prospective lumbar discectomy study of the joint section on disorders of the spine and peripheral nerves of the American Association of Neurological Surgeons and the Congress of Neurological Surgeons" Neurosurgery; 29:301-308

35) Postacchini F, et al. (1992) "Microdiscectomy in lumbar disc herniations." Ital J Orthop Traumatolo ; 18:331-8

36) Tulleberg T, et al. (1993) "Does microscopic removal of lumbar disc herniation lead to better results than the standard procedure? Results of a one-year randomized study: Spine; 18:24 -7

37) Lewis PJ, et al. (1987) "Long-term prospective study of lumbosacral discectomy." Neurosurg; 67:49-53

38) Salenius P, Laurent LE, (1977) "Results of operative treatment of lumbar disc herniation." Acta Orthop Scand; 48:630-4

39) Pappas CTE, et al. (1992) "Outcome analysis in 654 surgically treated lumbar disc herniations." Neurosurgery ;30:862 -6

40) Hakelius A. (1970) "Prognosis in sciatica." Acta Orthop Scand Suppl ; 129:1-76