Thoracic Disc Disease Management
ABSTRACTS & COMMENTARY
Sources: Stillerman CB, et al. Experience in the surgical management of 82 symptomatic herniated thoracic discs and review of the literature. J Neurosurg 1998;88:623-633; Bilsky MH, Patterson RH. The transpedicular approach for thoracic disc herniations. In: Benzel EC, Stillerman CB (eds): The Thoracic Spine. St. Louis: Quality Medical; 1998.
In a previous issue of Neurology Alert (1998;16:63), we discussed the much less common presentation of T1-2 disc herniations. Now, Stillerman et al review the management of 82 symptomatic herniated thoracic discs in 71 patients (34 men, 37 woman; ages 19-75 years; mean age, 48 years). The most common sites of disc herniation were from T-8 to T-11, with evidence of antecedent trauma in 37% of patients.
Pre-operative symptoms included pain (localized, axial, radicular) in 54 (76%), myelopathy with motor impairment in 43 (61%), hyperreflexia and spasticity in 41 (58%), sensory impairment in 43 (61%), and bladder dysfunction in 17 (24%). Disc calcification was 94% centrolateral and 6% lateral, with 61% showing calcification. Four surgical approaches were used: transthoracic in 60%, transfacet-pedicle sparing in 28%, lateral extracavitary in 10%, and transpedicular in 2%.
Post-operatively, there was improvement in pain in 87%, hyperreflexia and spasticity in 95%, sensory changes in 84%, bowel/bladder dysfunction in 76%, and motor impairment in 56%. Complications occurred in 12 of 82 discs (14.6%) treated surgically. Major complications were seen in three cases and included perioperative cardiopulmonary death, spinal instability requiring further surgery, and an increase in the degree of paraparesis.
Bilsky and Patterson review their New York Hospital experience in 20 patients (ages 25-79; mean, 47 years, with an equal sex distribution) using the transpedicular approach exclusively. A precipitating traumatic event was identified in 13 of the 20 patients. The most common levels were T8-9 and T11-12. Myelopathic syndromes at presentation were seen in 14 patients (8 predominantly motor, 6 bowel/bladder) and in six cases with radiculopathy. At surgery, 10 discs were calcified, and two had intradural fragments.
All 14 patients with myelopathy showed improved motor function, and all but one of six regained bowel/ bladder function postoperatively. Six patients with radiculopathy did not improve to the same degree-two cases with complete resolution, two with partial improvement in pain, and two unchanged. Complications including wound infection occurred in three patients.
COMMENTARY
The differential diagnosis of thoracic disc herniation includes a number of intra-and extramedullary processes, including AVM, spinal cord tumors, syringomyelia, epidural infection, and primary or metastatic vertebral body tumors. Multiple sclerosis with related demyelinating or inflammatory myelopathies and motor neuron disease (ALS/PLS) should also be considered. This is true even if a thoracic disc is seen on imaging studies, as many are noncontributory to the clinical condition. Thoracic discs are less commonly encountered in clinical practice, and indications for surgery are not well established because the natural history is not well defined. These two papers, which also include a helpful review of contemporary series, provide a better understanding of the clinical management of thoracic disc disease. The presence of a severe progressive myelopathy is generally regarded as an absolute indication for surgery. The clinical management, both medical and surgical, is thoughtfully conveyed by Stillerman et al in a treatment algorithm.
In their decision-making process, patients presenting with thoracic discs are entered into one of three groups. Those with localized pain without myelopathy are managed conservatively with steroidal and NSAIDs, bracing, activity modification, and physical therapy. Radiculopathy is also managed medically as above, including occasional steroid injections. For severe, radicular pain, patients are evaluated for posterolateral surgery for decompression. Myelopathy with significant disc herniation depends on the neurologic status. Patients with a static non-severe deficit are monitored and medically treated. For progressive severe deficits, low-risk patients with lateral herniation undergo posterolateral surgery. The more common centrolateral disc herniations are more complex. Soft discs can often be managed posterolaterally. Densely calcified discs, which can have dural adherence, are sometimes better managed by an anterolateral approach to avoid cord complications, despite the more extensive transthoracic surgery. However, there may be a trend in successful posterolateral approaches (transfacet pedicle sparing, transpedicular) in experienced centers for the spectrum of disc disease. -ba
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