Object. A variety of factors may affect surgery-related outcome in patients with ossification of the ligamentum flavum (OLF) of the thoracic spine. The aim of this study was to determine these factors on the basis of preoperative clinical and radiological findings. Methods. The authors treated 31 cases of symptomatic thoracic OLF between 1988 and 1999. The following factors were retrospectively studied: patient age, sex, morbidity level, initial symptoms, chief complaint, duration of symptoms, patellar reflex, Achilles reflex, computerized tomography (CT) finding, presence of intramedullary change determined by magnetic resonance imaging, coexistent spinal lesions, preoperative grade, and postoperative grade. A decompressive laminectomy was performed in all cases. In 29 patients (94%) improved symptoms were demonstrated postoperatively. In terms of functional prognosis, the preoperative duration of symptoms was significantly shorter in the group of patients with excellent outcomes than in those with fair outcomes (p < 0.05). No significant difference was observed in the correlation between other factors. To evaluate the degree of preoperative thoracic stenosis and the severity/extent of OLF-induced spinal compression, we used an original OLF CT scoring system. A score of excellent on the CT scale tended to indicate an excellent prognosis (p < 0.01). Conclusions. Thoracic OLF frequently develops in the lower-thoracic spine in middle-aged men, and it is complicated by various spinal lesions in many cases. Early diagnosis and treatment are important for understanding the clinical symptoms and imaging diagnosis because the present findings suggest that a delay in diagnosis and treatment correlates with the functional prognosis postoperatively.

Damage to the paraspinal muscle after various lumbar back surgery procedures was evaluated by measuring the paraspinal muscle thickness preoperatively and postoperatively in 89 patients, 61 males and 28 females. There were 42 single interlaminar level procedures (SL group), 13 multiple interlaminar level procedures (ML group), and 34 posterolateral fusion procedures (PLF group). Changes in paraspinal muscle thickness were evaluated at more than 10 months after surgery, because muscle swelling continued as long as 10 months after surgery, and then reduced as the edema subsided. Postoperative serum creatine phosphokinase (CPK) level on postoperative day 2 was also measured. The decrease of paraspinal muscle thickness was significantly larger in the PLF group than in the SL group (-12.9% and -2.7%, respectively, p < 0.02). There was no significant correlation between postoperative serum CPK level and decrease of paraspinal muscle thickness. However, the postoperative elevation of serum CPK level was significantly higher in the PLF group than in the SL and ML groups (979 +/- 114 vs. 292 +/- 45 and 410 +/- 44 IU/l, respectively, p < 0.001). In conclusion, posterolateral fusion is the most invasive procedure of the paraspinal muscles in various lumbar back surgery procedures. Paraspinal muscle damage during lumbar back surgery may be one of the most important factors that causes atrophy of the muscles.

Sixteen cases of thoracic radiculomyelopathy due to ossification of the ligamentum flavum (OLF) were analyzed. The patients ranged in age from 39 to 78 years (average 57 years). There were 13 men and 3 women. A significant predilection of OLF for the lower thoracic spine (T9/10, T10/11, T11/12) was noticed. Plain X-ray of the thoracic spine and multidirectional tomography could give important information about the site of ossification. Computed tomography with the intrathecal injection of the water-soluble contrast material clearly demonstrated the ossification and the degree of compression of the spinal cord. The disadvantages of using computed tomography for diagnosing OLF included the necessity for the scan level to be previously decided by other methods because computed tomography of the entire spine was impractical. Magnetic resonance imaging was performed in 14 patients and gave important information about OLF and the compression of the spinal cord. The combination of MRI and computed tomography seems the most useful for the precise diagnosis of OLF.

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A case of capillary hemangioma of the cauda equina is reported. Myelography with water-soluble contrast material showed a complete obstruction of the contrast column at the L1-L2 level. Neither plain nor intravenously enhanced CT revealed the tumor. Spinal angiography showed a feeding vessel to the tumor and a faint tumor stain. Magnetic resonance imaging (MRI) showed a mass lesion of slightly higher than cauda equina intensity, which was clearly enhanced with Gd-DTPA. MRI, especially Gd-DTPA-enhanced study, plays the most important role in the diagnosis of a spinal capillary hemangioma. Spinal angiography was interesting in showing a tumour with a capillary blush.