Global brain hypoperfusion and oxygenation in amnestic mild cognitive impairment.

BACKGROUND: To determine if global brain hypoperfusion and oxygen hypometabolism occur in patients with amnestic mild cognitive impairment (aMCI). METHODS: Thirty-two aMCI and 21 normal subjects participated. Total cerebral blood flow (TCBF), cerebral metabolic rate of oxygen (CMRO2), and brain tissue volume were measured using color-coded duplex ultrasonography (CDUS), near-infrared spectroscopy (NIRS), and MRI. TCBF was normalized by total brain tissue volume (TBV) for group comparisons (nTCBF). Cerebrovascular resistance (CVR) was calculated as mean arterial pressure divided by TCBF. RESULTS: Reductions in nTCBF by 9%, CMRO2 by 11%, and an increase in CVR by 13% were observed in aMCI relative to normal subjects. No group differences in TBV were observed. nTCBF was correlated with CMRO2 in normal controls, but not in aMCI. CONCLUSIONS: Global brain hypoperfusion, oxygen hypometabolism, and neurovascular decoupling observed in aMCI suggest that changes in cerebral hemodynamics occur early at a prodromal stage of Alzheimer's disease, which can be assessed using low-cost and bedside-available CDUS and NIRS technology.

Analysis of prevertebral soft-tissue swelling and dysphagia in multilevel anterior cervical discectomy and fusion with recombinant human bone morphogenetic protein-2 in patients at risk for pseudarthrosis.

OBJECT: The goal of this study was to demonstrate the incidence of fusion and soft-tissue swelling in multilevel anterior cervical discectomies and fusions (ACDFs) using polyetheretherketone (PEEK) spacers with recombinant human bone morphogenetic protein-2 (rhBMP-2) impregnated in a Type I collagen sponge and titanium plates. METHODS: A single surgeon performed 30 multilevel ACDFs using PEEK spacers with an rhBMP-2 impregnated collagen sponge (0.4 ml, or the equivalent of 0.6 mg rhBMP-2). Soft-tissue swelling was assessed using cervical spine radiographs on postoperative Day 1 and at 2, 6, and 10 weeks and 6 months after surgery. Incidence of dysphagia was assessed with the Cervical Spine Research Society Swallowing-Quality of Life tool. Clinical success was evaluated with the Neck Disability Index, neck pain scores, and arm pain scores. Final fusion was assessed with CT by an independent neuroradiologist. RESULTS: Patients were followed for 6 months unless they had an incomplete fusion; those patients were reassessed at 9 months. Twenty-four patients underwent 2-level ACDFs and 6 underwent 3-level ACDFs were performed on patients with the following risk factors for pseudarthrosis: smoking (33%), diabetes (13%), and obesity (body mass index ≥ 30 [43%]). Seventeen percent of the patients had multiple risk factors. Soft-tissue swelling peaked at 2 weeks regardless of level of surgery or number of levels treated surgically and decreased to near preoperative levels by 6 months. At 2 weeks, Swallowing-Quality of Life evaluation showed 19% of patients frequently choking on food, 4.8% frequently choking when drinking, and 47.6% with frequent food sticking in the throat. Scores continued to improve, and at 6 months, 0% had frequent choking on food, 6.7% had frequent difficulty drinking, and 6.7% had frequent food sticking in the throat. The Neck Disability Index, neck pain, and arm pain scores all improved progressively over 6 months. Incidence of fusion was 95% at 6 months and 100% at 9 months. There were no rehospitalizations or reoperations for soft-tissue swelling or dysphagia. CONCLUSIONS: Multilevel ACDF procedures using PEEK grafts and rhBMP-2 can be performed safely in patients with multiple risk factors for pseudarthrosis with excellent fusion outcomes.