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Satoshi Yamaguchi, Kuniki Eguchi, Yoshihiro Kiura, Masaaki Takeda, and Kaoru Kurisu

Object

The vertebral artery (VA) often takes a protrusive course posterolaterally over the posterior arch of the atlas. In this study, the authors attempted to quantify this posterolateral protrusion of the VA.

Methods

Three-dimensional CT angiography images obtained for various cranial or cervical diseases in 140 patients were reviewed and evaluated. Seven patients were excluded for various reasons. To quantify the protrusive course of the VA, the diameter of the VA and 4 parameters were measured in images of the C1–VA complex obtained in the remaining 133 patients. The authors also checked for anomalies and anatomical variations.

Results

When there was no dominant side, mean distances from the most protrusive part of the VA to the posterior arch of the atlas were 6.73 ± 2.35 mm (right) and 6.8 ± 2.15 mm (left). When the left side of the VA was dominant, the distance on the left side (8.46 ± 2.00 mm) was significantly larger than that of the right side (6.64 ± 2.0 mm). When compared by age group (≤ 30 years, 31–60 years, and ≥ 61 years), there were no significant differences in the extent of the protrusion. When there was no dominant side, the mean distances from the most protrusive part of the VA to the midline were 30.73 ± 2.51 mm (right side) and 30.79 ± 2.47 mm (left side). When the left side of the VA was dominant, the distance on the left side (32.68 ± 2.03 mm) was significantly larger than that on the right side (29.87 ± 2.53 mm). The distance from the midline to the intersection of the VA and inner cortex of the posterior arch of the atlas was ~ 12 mm, irrespective of the side of VA dominance. The distance from the midline to the intersection of the VA and outer cortex of the posterior arch was ~ 20 mm on both sides. Anatomical variations and anomalies were found as follows: bony bridge formation over the groove for the VA on the posterior arch of C-1 (9.3%), an extracranial origin of the posterior inferior cerebellar artery (8.2%), and a VA passing beneath the posterior arch of the atlas (1.8%).

Conclusions

There may be significant variation in the location and branches of the VA that may place the vessel at risk during surgical intervention. If concern is noted about the vulnerability of the VA or its branches during surgery, preoperative evaluation by CT angiography should be considered.

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Kazunori Arita, Atsushi Tominaga, Kazuhiko Sugiyama, Kuniki Eguchi, Koji Iida, Masayuki Sumida, Keisuke Migita, and Kaoru Kurisu

Object

The increase in the incidental detection of asymptomatic pituitary adenomas, known as “pituitary inciden-talomas,” led the authors to conduct a survey of the natural course of these lesions.

Methods

Forty-two patients with clinically nonfunctioning pituitary adenomas who had manifested no neurological or endocrinological disorders were monitored with magnetic resonance imaging studies. The follow-up period ranged from 10.8 to 168.2 months (mean ± standard deviation, 61.9 ± 38.2 months). The mean initial tumor size was 18.3 ± 7 mm.

In 21 patients, the tumor increased by at least 10% of its measured size on detection. This increase was first detected between 8.4 and 58.8 months (mean 31.8 ± 17.6 months) after diagnosis. There was no correlation between the original tumor size, patient age, or the presence of intratumoral cysts and tumor growth. Symptoms were noted in 10 patients during follow up; in four, extensive tumor necrosis accompanied hemorrhage, leading to severe headache, acute ophthalmological symptoms, and panhypopituitarism, which was indicative of pituitary apoplexy. Transsphenoidal surgery was performed in 12 patients with enlarged tumors, including three with apoplexy. With the exception of one apoplectic patient, visual function was recovered in all who underwent surgery. All apoplectic patients continue to manifest hypopituitarism.

Conclusions

In the course of 4 years, the size of the incidentalomas increased in 40% of 42 patients and became symptomatic in 20%. During the 5-year follow up, pituitary apoplexy developed in 9.5%. These findings may justify early intervention, especially in young individuals with incidentally found macroadenoma.

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Seiji Hama, Kazunori Arita, Takashi Nishisaka, Toshiyuki Fukuhara, Atsushi Tominaga, Kazuhiko Sugiyama, Hiroyuki Yoshioka, Kuniki Eguchi, Masayuki Sumida, Yuji Heike, and Kaoru Kurisu

Object. Rathke cleft cysts (RCCs) are composed of tall, well-differentiated, ciliated columnar epithelia. Their structures are altered by hyperplasia or squamous metaplasia, but their cause remains unknown.

Methods. The authors studied pathological findings and anterior pituitary function in 20 patients harboring RCCs. They classified RCC epithelium as either single (a single ciliated columnar cell lining or a flattened cuboidal cell lining) or stratified (a stratified ciliated columnar cell lining, basal cell hyperplasia, columnar cell hyperplasia, or squamous metaplasia). Inflammation was classified as acute, subacute, chronic, or end stage.

The epithelial cell lining was observed in 13 specimens obtained during surgery (six specimens contained single and seven contained stratified epithelia). Inflammation had penetrated the cyst epithelium or subjacent stroma in 10 patients, and the stage of inflammation correlated well with the type of epithelia group: early stages of inflammation in the single epithelium group and chronic or end-stage inflammation in the stratified epithelia (p = 0.0027). The adenohypophysis was identified in 21 surgical specimens. Postoperatively, growth hormone (p = 0.019), cortisol (p = 0.027), and thyroid-stimulating hormone (p = 0.039) responses significantly worsened as the inflammation progressed. The presence of diabetes insipidus correlated well with advanced stages of neurohypophysitis (p = 0.025).

Conclusions. Epithelial stratification in the RCC is caused by inflammation that may extend into the adjacent adenohypophysis or neurohypophysis and overwhelm the hypophysis, resulting in panhypopituitarism. Transsphenoidal excision may represent the best choice for treatment, at least for cases of RCC in which there is partial impairment of hypophysial function.

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Satoshi Yamaguchi, Tetsuya Nagayama, Kuniki Eguchi, Masaaki Takeda, Kazunori Arita, and Kaoru Kurisu

Object

The purpose of this study was to evaluate the accuracy of multidetector-row CT angiography (MDCTA) in demonstrating spinal dural arteriovenous fistulas (SDAVFs).

Methods

The authors studied 10 patients with SDAVFs, including 2 with spinal epidural AVFs, who underwent preoperative MR imaging, MDCTA, and digital subtraction angiography (DSA). In the evaluation of coronal sections of multiplanar reformation MDCTA images, inspection was focused on the presence of the following findings: 1) dilated perimedullary veins in the spinal canal; 2) focal enhancement of the nerve root, suggesting the location of the AVF, around the dural sleeve; and 3) a radicular vein that drains the AVF into perimedullary veins. The utility of MDCTA was assessed by comparing its findings with those of DSA in each case.

Results

Digital subtraction angiography confirmed that the AVFs were located in the thoracic spine in 4 patients and in the lumbar spine in 6 patients, and MDCTA detected dilated perimedullary veins in all 10 patients. In 8 patients, there was focal enhancement of the nerve root. The radicular vein that drains the AVF into the perimedullary veins was found in 8 cases. In 8 cases, the MDCTA-derived level and side of the AVF and its feeder corresponded with those shown by DSA. In 2 patients, however, the MDCTA-derived side of the feeder was on the side contralateral to the feeding artery confirmed by DSA. These lesions were interpreted as spinal epidural AVFs with perimedullary drainage. In 2 cases, MDCTA could not detect the multiplicity of their feeders.

Conclusions

The use of MDCTA preceding DSA can be helpful to focus the selective catheter angiography on certain spinal levels. However, one should keep in mind that epidural AVFs with perimedullary drainage may resemble SDAVFs and also that MDCTA cannot exclude the possibility of multiple feeders. Further research should elucidate how broadly selective angiography should explore around the MDCTA-suggested target.