Minimally Effective Dose of Bone Morphogenetic Protein in Minimally Invasive Lumbar Interbody Fusions: Six Hundred Ninety Patients in a Dose-Finding Longitudinal Cohort Study.

STUDY DESIGN: Retrospective longitudinal cohort. OBJECTIVE: We sought to demonstrate the minimally effective bone morphogenetic protein (BMP) dose to achieve fusion in minimally invasive transforaminal lumbar interbody fusions. SUMMARY OF BACKGROUND DATA: Multiple studies have been conducted, which used a wide range of BMP doses for lumbar fusions highlighting associated risks and benefits. There is, however, a paucity in the literature in determining the minimally effective dose. METHODS: Consecutive patients who underwent transforaminal lumbar interbody fusion from 2009 to 2014 were reviewed. Fusion was determined by a combination of computed tomography and dynamic x-ray by independent radiologists. We used backward stepwise multiple logistic regression with fusion as the dependent variable to determine whether BMP dose/level was a significant predictor for fusion. To determine the minimally effective dose of BMP/level, separate logistic regressions for different BMP dose ranges and sensitivity analyses were used. A P value ≤0.025 was considered significant. RESULTS: There were 1102 interspaces among 690 patients. Average BMP dose was 1.28 mg/level. Overall fusion was 95.2% with a mean follow-up of 19 months. BMP dose/level was a significant predictor for fusion. Odds of fusion increased by 2.02 when BMP dose range was increased from (0.16-1 mg/level) to (1.0-2 mg/level), but fusion odds did not increase when BMP dose increased to more than 2 mg/level. CONCLUSION: BMP dose/level was a significant predictor for fusion. There was a significant increase in odds of fusion when BMP dose increased from 0.16 to 1 mg/level to 1.0 to 2 mg/level. No benefit from increasing the dose more than 2 mg/level was found, suggesting 1.0 mg/level to be the minimally effective BMP dose. LEVEL OF EVIDENCE: 3.

Functional anastomotic relationship between the supratrochlear and facial arteries: an anatomical study.

BACKGROUND: For the past 15 years, a forehead flap with its pedicle based at or below the medial canthus has been used without any flap loss. This study describes the anatomical vascular relationships allowing this flap design to be successful. METHODS: Nine fresh frozen cadaver heads were studied in three groups. Six heads were injected with red latex. In group I, the supraorbital, supratrochlear, and facial arteries of four heads were dissected out under the operating microscope. In group II, using two latex-injected heads, the median forehead flap was elevated in the extended fashion and the arteries within the flap were dissected. The distal portion of the flap was elevated supraperiosteally and the proximal portion was elevated subperiosteally. In group III, the arterial systems of three heads were injected with barium solution after the flaps had been elevated. Radiographic assessment was used to demonstrate the vascular pattern within the flap. RESULTS: Group I showed an anastomotic relationship between the supratrochlear and facial arteries and a consistent relationship between the infraorbital and facial arteries. Group II showed that the above-mentioned connections could be protected during the supraperiosteal and subperiosteal flap elevation. This was confirmed by radiographic assessment in group III. The vascular network of the flap was filled through the facial artery by means of the dorsal nasal and supratrochlear arteries. CONCLUSIONS: Within the paranasal and medial canthal region, there is an anastomotic relationship between the supratrochlear, infraorbital, and branches of the facial arteries, and branches from the contralateral side, creating a rich vascular arcade. This allows a median forehead flap to be narrowly based at the level of the medial canthus.

The vestibulocochlear nerve.

The eighth nerve provides sensory connection for balance and sound. Our ability to evaluate its morphology and pathology with magnetic resonance imaging (MRI) has been substantially improved over the past 20 years. This article reviews the relevant anatomy of the eighth nerve. A thorough discussion of the potential pathologic processes affecting its function also is included. Foremost, is a review of acoustic schwannomas, emphasizing the role of imaging in the work-up and ongoing evaluation of these patients. Discussion and examples of the plethora of neoplastic, inflammatory, infectious, congenital, ischemic, and compressive pathologies involving the nerve are included as well.