Developmental changes in gamma-aminobutyric acid levels in attention-deficit/hyperactivity disorder.

While the neurobiological basis and developmental course of attention-deficit/hyperactivity disorder (ADHD) have not yet been fully established, an imbalance between inhibitory/excitatory neurotransmitters is thought to have an important role in the pathophysiology of ADHD. This study examined the changes in cerebral levels of GABA+, glutamate and glutamine in children and adults with ADHD using edited magnetic resonance spectroscopy. We studied 89 participants (16 children with ADHD, 19 control children, 16 adults with ADHD and 38 control adults) in a subcortical voxel (children and adults) and a frontal voxel (adults only). ADHD adults showed increased GABA+ levels relative to controls (P = 0.048), while ADHD children showed no difference in GABA+ in the subcortical voxel (P > 0.1), resulting in a significant age by disorder interaction (P = 0.026). Co-varying for age in an analysis of covariance model resulted in a nonsignificant age by disorder interaction (P = 0.06). Glutamine levels were increased in children with ADHD (P = 0.041), but there was no significant difference in adults (P > 0.1). Glutamate showed no difference between controls and ADHD patients but demonstrated a strong effect of age across both groups (P < 0.001). In conclusion, patients with ADHD show altered levels of GABA+ in a subcortical voxel which change with development. Further, we found increased glutamine levels in children with ADHD, but this difference normalized in adults. These observed imbalances in neurotransmitter levels are associated with ADHD symptomatology and lend new insight in the developmental trajectory and pathophysiology of ADHD.

Glutamate/glutamine and neuronal integrity in adults with ADHD: a proton MRS study.

There is increasing evidence that abnormalities in glutamate signalling may contribute to the pathophysiology of attention-deficit hyperactivity disorder (ADHD). Proton magnetic resonance spectroscopy ([1H]MRS) can be used to measure glutamate, and also its metabolite glutamine, in vivo. However, few studies have investigated glutamate in the brain of adults with ADHD naive to stimulant medication. Therefore, we used [1H]MRS to measure the combined signal of glutamate and glutamine (Glu+Gln; abbreviated as Glx) along with other neurometabolites such as creatine (Cr), N-acetylaspartate (NAA) and choline. Data were acquired from three brain regions, including two implicated in ADHD-the basal ganglia (caudate/striatum) and the dorsolateral prefrontal cortex (DLPFC)-and one 'control' region-the medial parietal cortex. We compared 40 adults with ADHD, of whom 24 were naive for ADHD medication, whereas 16 were currently on stimulants, against 20 age, sex and IQ-matched healthy controls. We found that compared with controls, adult ADHD participants had a significantly lower concentration of Glx, Cr and NAA in the basal ganglia and Cr in the DLPFC, after correction for multiple comparisons. There were no differences between stimulant-treated and treatment-naive ADHD participants. In people with untreated ADHD, lower basal ganglia Glx was significantly associated with more severe symptoms of inattention. There were no significant differences in the parietal 'control' region. We suggest that subcortical glutamate and glutamine have a modulatory role in ADHD adults; and that differences in glutamate-glutamine levels are not explained by use of stimulant medication.

Age dependent electroencephalographic changes in attention-deficit/hyperactivity disorder (ADHD).

OBJECTIVE: Objective biomarkers for attention-deficit/hyperactivity disorder (ADHD) could improve diagnostics or treatment monitoring of this psychiatric disorder. The resting electroencephalogram (EEG) provides non-invasive spectral markers of brain function and development. Their accuracy as ADHD markers is increasingly questioned but may improve with pattern classification. METHODS: This study provides an integrated analysis of ADHD and developmental effects in children and adults using regression analysis and support vector machine classification of spectral resting (eyes-closed) EEG biomarkers in order to clarify their diagnostic value. RESULTS: ADHD effects on EEG strongly depend on age and frequency. We observed typical non-linear developmental decreases in delta and theta power for both ADHD and control groups. However, for ADHD adults we found a slowing in alpha frequency combined with a higher power in alpha-1 (8-10Hz) and beta (13-30Hz). Support vector machine classification of ADHD adults versus controls yielded a notable cross validated sensitivity of 67% and specificity of 83% using power and central frequency from all frequency bands. ADHD children were not classified convincingly with these markers. CONCLUSIONS: Resting state electrophysiology is altered in ADHD, and these electrophysiological impairments persist into adulthood. SIGNIFICANCE: Spectral biomarkers may have both diagnostic and prognostic value.

Physiological and psychological individual differences influence resting brain function measured by ASL perfusion.

Effects of physiological and/or psychological inter-individual differences on the resting brain state have not been fully established. The present study investigated the effects of individual differences in basal autonomic tone and positive and negative personality dimensions on resting brain activity. Whole-brain resting cerebral perfusion images were acquired from 32 healthy subjects (16 males) using arterial spin labeling perfusion MRI. Neuroticism and extraversion were assessed with the Eysenck Personality Questionnaire-Revised. Resting autonomic activity was assessed using a validated measure of baseline cardiac vagal tone (CVT) in each individual. Potential associations between the perfusion data and individual CVT (27 subjects) and personality score (28 subjects) were tested at the level of voxel clusters by fitting a multiple regression model at each intracerebral voxel. Greater baseline perfusion in the dorsal anterior cingulate cortex (ACC) and cerebellum was associated with lower CVT. At a corrected significance threshold of p < 0.01, strong positive correlations were observed between extraversion and resting brain perfusion in the right caudate, brain stem, and cingulate gyrus. Significant negative correlations between neuroticism and regional cerebral perfusion were identified in the left amygdala, bilateral insula, ACC, and orbitofrontal cortex. These results suggest that individual autonomic tone and psychological variability influence resting brain activity in brain regions, previously shown to be associated with autonomic arousal (dorsal ACC) and personality traits (amygdala, caudate, etc.) during active task processing. The resting brain state may therefore need to be taken into account when interpreting the neurobiology of individual differences in structural and functional brain activity.

Quantitative cerebral perfusion imaging in children and young adults with Moyamoya disease: comparison of arterial spin-labeling-MRI and H(2)[(15)O]-PET.

BACKGROUND AND PURPOSE: Cerebral perfusion assessment is important in the preoperative evaluation and postoperative follow-up of patients with Moyamoya disease. The objective of this study was to evaluate the correlation of quantitative CBF measurements performed with arterial spin-labeling-MR imaging and H2[(15)O]-PET in children and young adults with Moyamoya disease. MATERIALS AND METHODS: Thirteen children and young adults (8 female patients; age, 9.7 ± 7.1 years; range, 1-23 years) with Moyamoya disease underwent cerebral perfusion imaging with H2[(15)O]-PET (Discovery STE PET/CT, 3D Fourier rebinning filtered back-projection, 128 × 128 × 47 matrix, 2.34 × 2.34 × 3.27 mm(3) voxel spacing) and arterial spin-labeling (3T scanner, 3D pulsed continuous arterial spin-labeling sequence, 32 axial sections, TR = 5.5 seconds, TE = 25 ms, FOV = 24 cm, 128 × 128 matrix, 1.875 × 1.875 × 5 mm(3) voxel spacing) within less than 2 weeks of each other. Perfusion of left and right anterior cerebral artery, MCA, and posterior cerebral artery territories was qualitatively assessed for arterial spin-labeling-MR imaging and H2[(15)O]-PET by 2 independent readers by use of a 3-point-Likert scale. Quantitative correlation of relative CBF with cerebellar normalization between arterial spin-labeling-MR imaging and H2[(15)O]-PET was evaluated in a volume-based approach for each vascular territory after 3D image coregistration. RESULTS: Interreader agreement was good (κ = 0.67-0.69), and strong and significant correlations were found between arterial spin-labeling-MR imaging and H2[(15)O]-PET for both qualitative perfusion scoring (ρ = 0.77; P < .001) and quantitative perfusion assessment of relative CBF with cerebellar normalization (r = 0.67, P < .001). CONCLUSIONS: In children and young adults with Moyamoya disease, quantitative evaluation of CBF is possible with the use of arterial spin-labeling-MR imaging without ionizing radiation or contrast injection with a good correlation to H2[(15)O]-PET after cerebellar normalization.

Reduced subcortical glutamate/glutamine in adults with autism spectrum disorders: a [¹H]MRS study.

Dysfunctional glutamatergic neurotransmission has been implicated in autism spectrum disorder (ASD). However, relatively few studies have directly measured brain glutamate in ASD adults, or related variation in glutamate to clinical phenotype. We therefore set out to investigate brain glutamate levels in adults with an ASD, comparing these to healthy controls and also comparing results between individuals at different points on the spectrum of symptom severity. We recruited 28 adults with ASD and 14 matched healthy controls. Of those with ASD, 15 fulfilled the 'narrowly' defined criteria for typical autism, whereas 13 met the 'broader phenotype'. We measured the concentration of the combined glutamate and glutamine signal (Glx), and other important metabolites, using proton magnetic resonance spectroscopy in two brain regions implicated in ASD--the basal ganglia (including the head of caudate and the anterior putamen) and the dorsolateral prefrontal cortex--as well as in a parietal cortex 'control' region. Individuals with ASD had a significant decrease (P<0.001) in concentration of Glx in the basal ganglia, and this was true in both the 'narrow' and 'broader' phenotype. Also, within the ASD sample, reduced basal ganglia Glx was significantly correlated with increased impairment in social communication (P=0.013). In addition, there was a significant reduction in the concentration of other metabolites such as choline, creatine (Cr) and N-acetylaspartate (NAA) in the basal ganglia. In the dorsolateral prefrontal cortex, Cr and NAA were reduced (P<0.05), although Glx was not. There were no detectable differences in Glx, or any other metabolite, in the parietal lobe control region. There were no significant between-group differences in age, gender, IQ, voxel composition or data quality. In conclusion, individuals across the spectrum of ASD have regionally specific abnormalities in subcortical glutamatergic neurotransmission that are associated with variation in social development.

Coupling between resting cerebral perfusion and EEG.

While several studies have investigated interactions between the electroencephalography (EEG) and functional magnetic resonance imaging BOLD signal fluctuations, less is known about the associations between EEG oscillations and baseline brain haemodynamics, and few studies have examined the link between EEG power outside the alpha band and baseline perfusion. Here we compare whole-brain arterial spin labelling perfusion MRI and EEG in a group of healthy adults (n = 16, ten females, median age: 27 years, range 21-48) during an eyes closed rest condition. Correlations emerged between perfusion and global average EEG power in low (delta: 2-4 Hz and theta: 4-7 Hz), middle (alpha: 8-13 Hz), and high (beta: 13-30 Hz and gamma: 30-45 Hz) frequency bands in both cortical and sub-cortical regions. The correlations were predominately positive in middle and high-frequency bands, and negative in delta. In addition, central alpha frequency positively correlated with perfusion in a network of brain regions associated with the modulation of attention and preparedness for external input, and central theta frequency correlated negatively with a widespread network of cortical regions. These results indicate that the coupling between average EEG power/frequency and local cerebral blood flow varies in a frequency specific manner. Our results are consistent with longstanding concepts that decreasing EEG frequencies which in general map onto decreasing levels of activation.

Magnetic resonance imaging features of large endolymphatic sac compartments: audiological and clinical correlates.

OBJECTIVES: (1) To study the prevalence and characteristics of large endolymphatic sac internal compartments on thin-section T2- and T2*-weighted magnetic resonance imaging, and to relate these to other large endolymphatic sac magnetic resonance imaging features, and (2) to correlate the compartment imaging features, endolymphatic sac size and labyrinthine anomalies with the patients' clinical and audiological data. METHOD: Magnetic resonance imaging studies for 38 patients with large endolymphatic sac anomalies were retrospectively reviewed in a tertiary referral centre. Endolymphatic sac compartment presence, morphology and imaging signal were assessed. Endolymphatic sac size and labyrinthine anomalies were also recorded. Endolymphatic sac compartments and other imaging features were correlated with clinical and audiological data. RESULTS: Compartments were present in 57 per cent of the imaged endolymphatic sacs, but their presence alone did not correlate with other imaging features or clinical data. The endolymphatic sac : internal auditory meatus signal ratio was associated with a history of sudden or fluctuating hearing loss. Hearing loss correlated with opercular and extraosseous endolymphatic sac size measurements. A larger midpoint intraosseous endolymphatic sac size was associated with clear fluid loss at cochlear implantation. CONCLUSION: The magnetic resonance imaging characteristics of large endolymphatic sac compartments have been defined. The endolymphatic sac size and distal compartment signal should be recorded, as these provide prognostic information and assist the planning of appropriate interventions.

Thalamic glutamate levels as a predictor of cortical response during executive functioning in subjects at high risk for psychosis.

CONTEXT: Alterations in glutamatergic neurotransmission and cerebral cortical dysfunction are thought to be central to the pathophysiology of psychosis, but the relationship between these 2 factors is unclear. OBJECTIVE: To investigate the relationship between brain glutamate levels and cortical response during executive functioning in people at high risk for psychosis (ie, with an at-risk mental state [ARMS]). DESIGN: Subjects were studied using functional magnetic resonance imaging while they performed a verbal fluency task, and proton magnetic resonance spectroscopy was used to measure their brain regional glutamate levels. SETTING: Maudsley Hospital, London, England. PATIENTS AND OTHER PARTICIPANTS: A total of 41 subjects: 24 subjects with an ARMS and 17 healthy volunteers (controls). MAIN OUTCOME MEASURES: Regional brain activation (blood oxygen level-dependent response); levels of glutamate in the anterior cingulate, left thalamus, and left hippocampus; and psychopathology ratings at the time of scanning. RESULTS: During the verbal fluency task, subjects with an ARMS showed greater activation than did controls in the middle frontal gyrus bilaterally. Thalamic glutamate levels were lower in the ARMS group than in control group. Within the ARMS group, thalamic glutamate levels were negatively associated with activation in the right dorsolateral prefrontal and left orbitofrontal cortex, but positively associated with activation in the right hippocampus and in the temporal cortex bilaterally. There was also a significant group difference in the relationship between cortical activation and thalamic glutamate levels, with the control group showing correlations in the opposite direction to those in the ARMS group in the prefrontal cortex and in the right hippocampus and superior temporal gyrus. CONCLUSIONS: Altered prefrontal, hippocampal, and temporal function in people with an ARMS is related to a reduction in thalamic glutamate levels, and this relationship is different from that in healthy controls.

CT and MR imaging cochlear distance measurements may predict cochlear implant length required for a 360 degrees insertion.

BACKGROUND AND PURPOSE: A preoperative prediction of the 360 degrees point insertion depth would aid the planning of electric acoustic stimulation (EAS) implantation. The purpose of this study was to establish whether the distance between the round window and the opposite cochlear wall on CT or MR imaging may be used to predict the length of a cochlear implant electrode array required to be inserted to the 360 degrees point of the basal turn. MATERIALS AND METHODS: CT and MR imaging data were studied in 19 patients undergoing cochlear implantation. Distances were measured between the round window and the opposite outer cochlear wall on an oblique paracoronal reformatted image. Adjusted distance measurements were applied to a spiral function to estimate the length of an electrode array extending between the round window entry point and the 360 degrees point. This was compared with measurements of implant length to this insertion depth on postoperative CT. RESULTS: Intraobserver reproducibility for each of the 2 observers was r = 0.85/0.55 for CT and r = 0.87/0.67 for MR imaging. Interobserver reproducibility was r = 0.68 for CT and r = 0.84 for MR imaging. There was no bias between CT and MR imaging measurements, with a mean difference of less than 0.1 mm. CT and MR imaging estimates markedly correlated with the actual length of the electrode array extending to the 360 degrees insertion depth (SD between the estimated and actual length was 0.84 mm for CT and 0.87 mm for MR imaging). CONCLUSIONS: CT and MR imaging measures of cochlear distance (CD) were used to predict insertion depths to 360 degrees , and these were markedly concordant with the actual length of the electrode array required to reach this point. MR imaging measurements were more precise and similar in accuracy to those obtained with CT.

Precision and accuracy of low-dose CT protocols in the evaluation of skull landmarks.

OBJECTIVES: It was proposed to design a series of low-dose three-dimensional (3D) CT protocols with an effective dose similar to that of the conventional radiographic series (0.011-0.032 mSv) used to assess craniofacial asymmetry. It was then aimed to assess the precision and accuracy for skull landmarks recorded ex vivo using these CT protocols. METHODS: Four ultra low-dose CT protocols (5 mAs, pitch 1.375/1.75; 10 mAs, pitch 1.375/1.75) were constructed on the basis of published data, dose calculations and measurements. A high-dose CT protocol was used as a reference standard examination. The protocols were used to scan a skull immersed in water. For each protocol, two observers evaluated 17 skull landmarks on two separate occasions. 3D and two-dimensional (2D) accuracy relative to the reference standard examination and inter- and intraobserver precision was calculated. RESULTS: The 2D accuracy was superior for the 10 mAs protocols and the 10 mAs/1.375 pitch protocol allowed one observer to achieve an accuracy of less than 2 mm for all landmarks. The 2D interrater precision for the 10 mAs/1.375 pitch protocol was superior to the other low-dose protocols and also the high-dose protocol, achieving precision less than 2 mm for 15/17 points. The 10 mAs protocols enabled greater 2D intrarater precision than the 5 mAs protocols for both observers. CONCLUSIONS: Using the 10 mAs/1.375 pitch CT protocol, it was possible to achieve 2D accuracy of less than 2 mm for almost all skull landmarks with an interrater precision similar to a high-dose CT protocol. Although the estimated effective dose of 0.035 mSv was slightly greater than that of the conventional radiographic series (0.011-0.032 mSv), there was the additional benefit of a 3D data set. The 10 mAs protocols allowed accuracy and precision superior to that of the 5 mAs protocols and hence they are more likely to be clinically applicable.

Parametric mapping of the hepatic perfusion index with gadolinium-enhanced volumetric MRI.

The purpose of this study was to adapt the hepatic perfusion index (HPI) methodology previously developed for MRI to derive 3D parametric maps of HPI, and to investigate apparent differences in HPI maps between a group of colorectal cancer patients and controls. To achieve this, a new and simpler approach to HPI calculation which does not require measurements from the aorta or portal vein is introduced, and assessed with large liver regions of interest (ROIs) in patients and controls. Several example HPI maps showing localized variation are then presented. The subject group consisted of 12 patients with known colorectal metastases, and 13 control subjects referred for routine contrast-enhanced spine imaging with no history of neoplastic disease. HPI was evaluated from serial T1 volume acquisitions acquired over the course of a Gd-DTPA bolus injection. Regions of abnormal perfusion were visible on the HPI maps derived for the patient group, manifested as areas of locally increased HPI extending around the visible margins of known metastases evident on the conventional contrast-enhanced images. This method for MR voxel-based parametric mapping of HPI has the potential to demonstrate regional variations in perfusion at the segmental and subsegmental level.

Personality factors correlate with regional cerebral perfusion.

There is an increasing body of evidence pointing to a neurobiological basis of personality. The purpose of this study was to investigate the biological bases of the major dimensions of Eysenck's and Cloninger's models of personality using a noninvasive magnetic resonance perfusion imaging technique in 30 young, healthy subjects. An unbiased voxel-based analysis was used to identify regions where the regional perfusion demonstrated significant correlation with any of the personality dimensions. Highly significant positive correlations emerged between extraversion and perfusion in the basal ganglia, thalamus, inferior frontal gyrus and cerebellum and between novelty seeking and perfusion in the cerebellum, cuneus and thalamus. Strong negative correlations emerged between psychoticism and perfusion in the basal ganglia and thalamus and between harm avoidance and perfusion in the cerebellar vermis, cuneus and inferior frontal gyrus. These observations suggest that personality traits are strongly associated with resting cerebral perfusion in a variety of cortical and subcortical regions and provide further evidence for the hypothesized neurobiological basis of personality. These results may also have important implications for functional neuroimaging studies, which typically rely on the modulation of cerebral hemodynamics for detection of task-induced activation since personality effects may influence the intersubject variability for both task-related activity and resting cerebral perfusion. This technique also offers a novel approach for the exploration of the neurobiological correlates of human personality.

Comparison of the hepatic perfusion index measured with gadolinium-enhanced volumetric MRI in controls and in patients with colorectal cancer.

The aim of the study was to adapt the methodology established for dynamic CT measurements of the hepatic perfusion index (HPI) to MRI, and to assess the potential role of MRI measurements of the HPI in detecting regional alterations in liver perfusion between patients with colorectal liver metastases and normal controls. The HPI was evaluated from serial T(1) volume acquisitions acquired over the course of a Gd-DTPA bolus injection. Time-course data from regions of interest in the liver, spleen and aorta were used to calculate the HPI; and HPI data from control subjects were compared with data from patients with known colorectal metastases. Significant differences were found between the relative portal perfusion and hepatic perfusion indices calculated for the patient and control groups (p<0.005). These results suggest that hepatic perfusion indices can be derived using MRI-based methods, and that these perfusion indices are sensitive to differences in liver perfusion associated with established metastatic liver disease on imaging. This technique may contribute to the early detection of liver metastases, allowing early surgical intervention and improved patient survival.

Magnetic resonance image registration and subtraction in the assessment of minor changes in low grade glioma volume.

The purpose of this study was to apply image registration and subtraction to standard T2-weighted (T2-W) and FLAIR magnetic resonance imaging (MRI) protocols in an attempt to improve the detection of minor changes in low grade glioma volume. Thirteen patients with low grade glial tumours and minimal or no apparent change on serial MRI scans were prospectively recruited for the study. Forty-two pairs of images were compared (T2-W sequences in 27/27 and FLAIR sequences in 15/27). The image pairs were registered, subtracted and randomised. Three independent raters assigned non-parametric ratings according to the dominant volume change for unregistered, registered and subtracted image sets. There was a statistically significant improvement in the detection of tumour volume change using T2-W registration and T2-W and FLAIR registration/subtraction relative to unregistered images. The reproducibility and increased sensitivity of FLAIR images relative to T2-W images were most apparent when registration was applied. Smaller degrees of low grade glioma tumour volume change are detectable using image registration and subtraction techniques that can be applied successfully to images acquired with standard clinical protocols.

SPAMM, cine phase contrast imaging and fast spin-echo T2-weighted imaging in the study of intracranial cerebrospinal fluid (CSF) flow.

AIM: To compare the qualitative assessment of cerebrospinal fluid (CSF) flow using a SPAMM (spatial modulation of magnetization) technique with cine phase contrast images (cine PC) and fast spin echo (FSE) T2-weighted images. MATERIALS AND METHODS: SPAMM, PC and T2-weighted sequences were performed on 22 occasions in 19 patients. Eleven of the studies were performed following a neuroendoscopic third ventriculostomy (NTV), and in these cases, the success of the NTV was determined by clinical follow-up. Two observers used consensus to grade the presence of CSF flow at nine different sites for each study. RESULTS: At 14 of the 178 matched sites, which could be assessed by both SPAMM and cine PC, SPAMM CSF flow grade was higher than that of cine PC. At a further 14/178 matched sites, the cine PC grade was higher than that of SPAMM. There was definite CSF flow at 113/182 (62%) of all the cine PC sites assessed, and 110/181 (61%) of all SPAMM sites assessed whilst 108/198 (54%) of FSE T2-weighted image sites demonstrated flow voids. Cine PC grades were higher than SPAMM at the cerebral aqueduct (P < 0.05, Wilcoxon sign rank test). Definite CSF flow within the anterior third ventricle was present in 4/5 (SPAMM) and 3/5 (cine PC) successful NTVs, 0/2 (SPAMM and cine PC) unsuccessful NTVs and 1/10 (SPAMM and cine PC) patients without NTV. CONCLUSION: SPAMM provides a comparable assessment of intracranial CSF flow to that of cine phase contrast imaging at all CSF sites except the cerebral aqueduct.

Glucose transport inhibitors protect against 1,2-cyclohexanedione-produced potassium loss from human red blood cells.

It has been suggested that the glucose transport system of human erythrocytes contains an arginine shield to prevent the leak of potassium through the transporter. To investigate this suggestion we treated human erythrocytes with the specific arginine reagent 1,2-cyclohexanedione. Under conditions which produce a covalent reaction between arginine and the reagent, a steady leak of potassium occurs. If glucose, maltose or the inhibitor phloretin are present during the reaction the extent of the leak is reduced. These findings support the view that arginines have a role in preventing potassium loss through the glucose transporter.

Management of vascular injuries in the lower extremities.

From 1981 through 1985, 220 consecutive patients with presumed vascular injuries in the lower extremities underwent operation at the Ben Taub General Hospital. More than 81% of injuries were due to penetrating wounds, and blunt and iatrogenic injuries accounted for the remainder. A preoperative emergency center arteriogram was performed in 63.2% of patients, and physical examination alone prompted operation in 36.8%. Eight patients underwent immediate amputation; the remaining 212 patients were found to have 225 arterial (63.9%) and 127 venous (36.1%) injuries. More than 50% of patients were noted to have both arterial and venous injuries. Arterial repair was most commonly accomplished by segmental resection with an end-to-end anastomosis (28.4%) or insertion of a graft (38.8%). Venous repair was most commonly accomplished by lateral venorrhaphy (48.8%), ligation (19.7%), or insertion of a conduit (18.1%). Postoperative infection in closed wounds, in wounds left open because of the magnitude of injury, and in adjacent fractured bone occurred in 13% of patients. Late amputations were necessary in only four patients, three of whom had infection as the cause.