Kuo-Wei Wang, Han-Jung Chen, Kang Lu, Po-Chou Liliang, Chun-Kai Huang, Pi-Lien Tang, Yu-Duan Tsai, Hao-Kuang Wang and Cheng-Loong Liang
The reported incidence of hospital-acquired bacterial pneumonia in critically ill trauma patients varies from as low as 4% to as high as 87%, with fatality rates varying from 6% to 59%. Clinical studies have identified the risk factors for pneumonia. The authors undertook this retrospective study to evaluate the incidence, risk factors, and outcomes of hospital-acquired bacterial pneumonia in a group of patients with severe head injuries.
This was a retrospective review of consecutive adult patients admitted to the neurosurgical ICU in the authors' hospital because of severe head injury (Glasgow Coma Scale scores ≤ 8) between January 2008 and December 2010.
During the study period, 290 patients were admitted to the neurosurgical ICU. Multivariate Cox regression analysis showed that age (HR 1.01, 95% CI 1.001–1.02), nasogastric tube insertion (HR 4.56, 95% CI 1.11–18.64), and hemiplegia or hemiparesis (HR 3.79, 95% CI 2.01–7.17) were significantly associated with the development of pneumonia.
The authors identified 3 risk factors (age, nasogastric tube insertion, and hemiplegia or hemiparesis) associated with the development of pneumonia in patients with severe head injury. This finding constituted the basis for developing a simple screening tool that can be used to assess the risk of occurrence of pneumonia in such patients.
John W. Rutland, Francesco Padormo, Cindi K. Yim, Amy Yao, Annie Arrighi-Allisan, Kuang-Han Huang, Hung-Mo Lin, James Chelnis, Bradley N. Delman, Raj K. Shrivastava and Priti Balchandani
The objective of this study was to investigate microstructural damage caused by pituitary macroadenomas by performing probabilistic tractography of the optic tracts and radiations using 7-T diffusion-weighted MRI (DWI). These imaging findings were correlated with neuro-ophthalmological results to assess the utility of ultra–high-field MRI for objective evaluation of damage to the anterior and posterior visual pathways.
Probabilistic tractography employing 7-T DWI was used to reconstruct the optic tracts and radiations in 18 patients with adenomas and in 16 healthy volunteers. Optic chiasm compression was found in 66.7% of the patients and visual defects in 61.1%. Diffusion indices were calculated along the projections and correlated with tumor volumes and results from neuro-ophthalmological examinations. Primary visual cortical thicknesses were also assessed.
Fractional anisotropy was reduced by 21.9% in the optic tracts (p < 0.001) and 17.7% in the optic radiations (p < 0.001) in patients with adenomas. Patients showed an 8.5% increase in mean diffusivity of optic radiations compared with healthy controls (p < 0.001). Primary visual cortical thickness was reduced in adenoma patients. Diffusion indices of the visual pathway showed significant correlations with neuro-ophthalmological examination findings.
Imaging-based quantification of secondary neuronal damage from adenomas strongly correlated with neuro-ophthalmological findings. Diffusion characteristics enabled by ultra–high-field DWI may allow preoperative characterization of visual pathway damage in patients with chiasmatic compression and may inform prognosis for vision recoverability.
John W. Rutland, Kuang-Han Huang, Corey M. Gill, Dillan F. Villavisanis, Judy Alper, Gaurav Verma, Joshua B. Bederson, Bradley N. Delman, Raj K. Shrivastava and Priti Balchandani
Trigeminal neuralgia (TN) is a debilitating neurological disease that commonly results from neurovascular compression of the trigeminal nerve (CN V). Although the CN V has been extensively studied at the site of neurovascular compression, many pathophysiological factors remain obscure. For example, thalamic-somatosensory function is thought to be altered in TN, but the abnormalities are inadequately characterized. Furthermore, there are few studies using 7-T MRI to examine patients with TN. The purpose of the present study was to use 7-T MRI to assess microstructural alteration in the thalamic-somatosensory tracts of patients with TN by using ultra–high field MRI.
Ten patients with TN and 10 age- and sex-matched healthy controls underwent scanning using 7-T MRI with diffusion tensor imaging. Structural images were segmented with an automated algorithm to obtain thalamus and primary somatosensory cortex (S1). Probabilistic tractography was performed between the thalamus and S1, and the microstructure of the thalamic-somatosensory tracts was compared between patients with TN and controls.
Fractional anisotropy of the thalamic-somatosensory tract ipsilateral to the site of neurovascular compression was reduced in patients (mean 0.43) compared with side-matched controls (mean 0.47, p = 0.01). The mean diffusivity was increased ipsilaterally in patients (mean 6.58 × 10−4 mm2/second) compared with controls (mean 6.15 × 10−4 mm2/second, p = 0.02). Radial diffusivity was increased ipsilaterally in patients (mean 4.91 × 10−4 mm2/second) compared with controls (mean 4.44 × 10−4 mm2/second, p = 0.01). Topographical analysis revealed fractional anisotropy reduction and diffusivity elevation along the entire anatomical S1 arc in patients with TN.
The present study is the first to examine microstructural properties of the thalamic-somatosensory anatomy in patients with TN and to evaluate quantitative differences compared with healthy controls. The finding of reduced integrity of these white matter fibers provides evidence of microstructural alteration at the level of the thalamus and S1, and furthers the understanding of TN neurobiology.