Risk Factors for Recurrent Disc Herniations

The risk factors for a primary disc herniation have been noted to include exposure to repetitive lifting, exposure to vibrations, smoking, and a constitutional weakness of the anular tissue.^13–15 Isolated trauma or injury has not been found to be a consistent risk factor, occurring in only 0.2% to 10.7% of adults with a herniation.^14,16 Conversely, Cinotti et al. found that 42% of patients with a recurrent disc herniation related the onset of radicular pain to an isolated injury or precipitating event.¹⁷ Similarly, Suk et al. reported the rate of an isolated injury as a cause of recurrence in 32.1%. This study also noted that 71.4% of the patients with recurrence were males and 57.1% were smokers.¹⁸

Despite these findings, other studies have found that gender, age, smoking status, level of herniation, and duration of symptoms were generally not associated with higher rates of recurrence.^8,9,17–19 Additionally, the degree of anular incision and the extent of the discectomy (partial or complete) have not been found to affect the potential for recurrence. ^9,17–19

One factor that potentially increases the likelihood of a recurrent disc herniation is diabetes. In general, patients with diabetes have been noted to have lower clinical success rates following the initial lumbar discectomy than do nondiabetic patients. Simpson et al. reported an excellent to good outcome following the initial discectomy of 95% in nondiabetic patients but only 39% in diabetic patients.²⁰ Mobbs et al. reported success rates of 86% in nondiabetic patients and 60% in diabetic patients.⁹ Although these clinical outcome differences were generally felt to be attributable to lower quality-of-life indicators in diabetic patients, Robinson et al. investigated the differences in the proteoglycan profile of the discs in the two groups. This study found that diabetic patients had fewer proteoglycans in the disc material, potentially increasing their susceptibility to recurrent disc prolapse.²¹

Another proposed risk factor is the configuration of the initial disc herniation. Suk et al. and Grane et al. noted that preoperative disc configuration does not affect the rate of recurrence.^18,22 Alternatively, Carragee et al. prospectively evaluated herniated disc configurations along with the rate of reherniation and the rate of reoperation. Disc herniations were divided into four shaped-based groups: (1) fragment-fissure herniations (disc fragment and small anular defect), (2) fragment-defect herniations (large disc fragment with massive dorsal anular tear), (3) fragment-contained discs (incomplete anular tear), and (4) absence of fragment-contained herniations (anular prolapse). Of the four groups, the fragment-fissure type herniations (group 1) were associated with the best outcomes and the lowest rate of reherniation (1%) and required the fewest reoperative procedures (1%). Those with anular prolapse (group 4) were associated with poorer clinical outcomes, with 38% of patients experiencing recurrent or persistent symptoms.⁸

Evaluation of Recurrent Disc Herniation

The patient who presents with a recurrent disc herniation has generally had a period of clinical improvement following the initial discectomy procedure. A retrospective review of 28 patients with recurrent disc herniation found a pain-free interval ranging from 7 to 168 months (mean of 60.8 months).¹⁸ Patients typically report radicular signs and symptoms similar or identical to those of their preoperative clinical state.

Pathologic changes in the ventral epidural space may reflect mass effect due to perineural scarring or recurrent disc herniation.^7,23 Scarring is most pronounced before 9 months and primarily involves the anulus fibrosus.²⁴ The scar may surround the nerve roots and cause symptoms by means of neural tension, decreased axoplasmic transport, restriction of blood flow, or restriction of venous return.⁷

MRI, with and without gadolinium contrast, is the preferred imaging modality for the assessment of a recurrent disc herniation.^7,10,25,26 The use of contrast material helps to differentiate normal postoperative anatomic changes from a recurrent herniation. Peridural scarring will typically enhance heterogeneously because of its vascular supply. A recurrent disc herniation usually appears as a polypoid mass with a low signal on T1- and T2-weighted sequences. It is usually contiguous with the parent disc unless sequestered. There can be a hypointense rim of the posterior longitudinal ligament and outer anular fibers that outline the herniation. This rim will enhance with contrast administration (Fig. 80-1). The disc itself will not enhance, because it has no blood supply.^7,27

FIGURE 80-1 Sagittal plane (A) and axial plane (B) MRIs following administration of contrast material demonstrating a recurrent disc herniation on the left side at the L4-5 level. The disc fragment is surrounded by a rim of enhancing scar tissue (arrows). The disc fragment itself does not enhance.