Object It is not known whether adding fusion to lumbar decompression is necessary for all patients undergoing surgery for degenerative lumbar spondylolisthesis with symptomatic stenosis. Determining specific radiographic traits that might predict delayed instability following decompression surgery might guide clinical decision making regarding the utility of up-front fusion in patients with degenerative Grade I spondylolisthesis. Methods Patients with Grade I degenerative lumbar spondylolisthesis (3–14 mm) with symptomatic stenosis were prospectively enrolled from a single site between May 2002 and September 2009 and treated with decompressive laminectomy without fusion. Patients with mechanical back pain or with gross motion (> 3 mm) on flexion-extension lumbar radiographs were excluded. The baseline radiographic variables measured included amount of slippage, disc height, facet angle, motion at spondylolisthesis (flexion-extension), and sagittal rotation angle. Data were analyzed using multivariate forward selection stepwise logistic regression, chi-square tests, Student t-test, and ANOVA. Results Forty patients were enrolled and treated with laminectomy without fusion, and all patients had complete radiographic data sets that were available for analysis. Reoperation was performed in 15 (37.5%) of 40 patients, with a mean follow-up duration of 3.6 years. Reoperation was performed for pain caused by instability at the index level in all 15 cases. Using multivariate stepwise logistic regression with a threshold p value of 0.35, motion at spondylolisthesis, disc height, and facet angle were predictors of reoperation following surgery. Facet angle > 50° was associated with a 39% rate of reoperation, disc height > 6.5 mm was associated with a 45% rate of reoperation, and motion at spondylolisthesis > 1.25 mm was associated with a 54% rate of reoperation. Patients with all 3 risk factors for instability had a 75% rate of reoperation, whereas patients with no risk factors for instability had a 0% rate of reoperation (p = 0.14). Conclusions Patients with motion at spondylolisthesis > 1.25 mm, disc height > 6.5 mm, and facet angle > 50° are more likely to experience instability following decompression surgery for Grade I lumbar spondylolisthesis. Identification of key risk factors for instability might improve patient selection for decompression without fusion surgery. Clinical trial registration no.: NCT00109213

Hypopituitarism is a major manifestation of pituitary adenoma apoplexy. We postulated that the acute deterioration in pituitary function may be caused by compression of portal vessels and the pituitary stalk, secondary to a sudden increase in intrasellar contents. If this were the case, one would predict improvement in pituitary function to occur after surgical decompression. We studied pituitary function in eight patients presenting with the clinical syndrome of pituitary adenoma apoplexy before and on multiple occasions after urgent surgical decompression. Partial or complete hypopituitarism was seen in all subjects at the time of presentation. Serum cortisol levels were inappropriately low (5.9 +/- 1.4 micrograms/dL; 162.8 +/- 38 nmol/L) for the degree of stress in seven patients and appropriately elevated in only one subject (55.3 micrograms/dL; 1525.7 nmol/L). High normal increments in cortisol levels were noted in three subjects given test doses of cosyntropin. Patients were given glucocorticoids before, during, and for 2 days after surgery. Serum cortisol concentrations measured on or after the third day when glucocorticoids had already been stopped were normal in seven subjects and consistently low in one. These seven subjects were discharged on no replacement and were subsequently documented by dynamic testing to have normal pituitary-adrenal function. Gonadal function improved in two of four men and in one of two women who had hypogonadism on presentation. Improvement in thyroid function was documented in two of three subjects with preoperative hypothyroidism. Gradual improvement and almost complete resolution of the neuroophthalmological abnormalities occurred days to weeks after decompression. These observations demonstrate that urgent surgical decompression after pituitary tumor apoplexy was associated with improvement not only in neurological defects but also in pituitary function. The rapid improvement in pituitary function indicates not only that the hypopituitarism was reversible, but also that it might be caused by compression of the portal circulation and pituitary stalk by the sudden increase in intrasellar contents.