Long-term survival after traumatic spinal cord injury: a 70-year British study

STUDY DESIGN

Retrospective and prospective observational.

OBJECTIVES

Analyse long-term survival after traumatic spinal cord injury (SCI) in Great Britain over the 70-year study period, identify mortality risk factors and estimate current life expectancy.

SETTING

Two spinal centres in Great Britain.

METHODS

The sample consisted of patients with traumatic SCI injured 1943-2010 who survived the first year post-injury, had residual neurological deficit on discharge and were British residents. Life expectancy and trends over time were estimated by neurological grouping, age and gender, using logistic regression of person-years of follow-up combined with standard life table calculations.

RESULTS

For the 5483 cases of traumatic SCI the mean age at injury was 35.1 years, 79.7% were male, 31.1% had tetraplegia AIS/Frankel ABC, 41.2% paraplegia ABC,and 27.7% functionally incomplete lesion (all Ds). On 31 December 2014, 54% were still alive, 42.3% had died and 3.7% were lost to follow-up. Estimated life expectancies improved significantly between the 1950s and 1980s, plateaued during the next two decades, before slightly improving again since 2010. The estimated current life expectancy, compared with the general British population, ranged from 18.1 to 88.4% depending on the ventilator dependency, level and completeness of injury, age and gender.

CONCLUSIONS

Life expectancy after SCI improved significantly between the 1950s and 1980s, plateaued during the 1990s and 2000s, before slightly improving again since 2010, but still remains well below that of the general British population.

SPONSORSHIP

Buckinghamshire Healthcare NHS Trust Charitable Spinal Fund and Ann Masson Legacy for Spinal Research Fund, UK.

Trauma-Related Critical Care

BACKGROUND

Post-trauma resuscitation has evolved based on civilian and wartime experiences over the last decade. Similarly, data from large multicenter randomized trials have changed the management of critically ill trauma patients in the intensive care unit.

METHODS

This is a review of the literature focusing on areas relevant to the management of trauma patients in the intensive care unit.

RESULTS

The following topics are included: (1) ventilator management, (2) trauma sepsis, (3) use of vasopressors in hemorrhage, (4) glucose control, (5) nutrition, and (6) hemodynamic monitoring.

CONCLUSION

This review demonstrated the most recent data of trauma-related critical care. Further studies will be needed to settle growing controversies in the management of critically injured patients.

Ethical considerations in the collection of genetic data from critically ill patients: what do published studies reveal about potential directions for empirical ethics research?

Critical illness trials involving genetic data collection are increasingly commonplace and pose challenges not encountered in less acute settings, related in part to the precipitous, severe and incapacitating nature of the diseases involved. We performed a systematic literature review to understand the nature of such studies conducted to date, and to consider, from an ethical perspective, potential barriers to future investigations. We identified 79 trials enrolling 24 499 subjects. Median (interquartile range) number of participants per study was 263 (116.75-430.75). Of these individuals, 16 269 (66.4%) were Caucasian, 1327 (5.4%) were African American, 1707 (7.0%) were Asian Pacific Islanders and 139 (0.6%) were Latino. For 5020 participants (20.5%), ethnicity was not reported. Forty-eight studies (60.8%) recruited subjects from single centers and all studies examined a relatively small number of genetic markers. Technological advances have rendered it feasible to conduct clinical studies using high-density genome-wide scanning. It will be necessary for future critical illness trials using these approaches to be of greater scope and complexity than those so far reported. Empirical research into issues related to greater ethnic inclusivity, accuracy of substituted judgment and specimen stewardship may be essential for enabling the conduct of such trials.

Inter-rater reliability of motor and sensory examinations performed according to American Spinal Injury Association standards

STUDY DESIGN

Prospective observational.

AIM

To examine inter-rater reliability of motor and sensory examinations performed according to American Spinal Injury Association (ASIA) standards.

SETTING

National Spinal Injuries Centre, Stoke Mandeville Hospital, Buckinghamshire Hospitals NHS Trust, UK.

MATERIAL AND METHOD

Results of ASIA motor and sensory examinations performed by two experienced examiners on 45 patients with spinal cord injury (SCI) were compared.

RESULTS

Total ASIA scores showed very strong correlation between the two examiners, with Pearson correlation coefficients and intraclass correlation coefficients exceeding 0.96, P<0.01 for total motor, light touch and pin prick scores. The agreement for individual muscle testing of the 10 ASIA key muscles showed substantial agreement for majority of muscles, with the weighted Kappa coefficient range 0.649-0.993, P<0.05. The overall agreement in assignment of manual muscle testing grades (0-5) was 82% on the right and 84% on the left, with the strongest agreement for grade '0' and the weakest for grade '3'. The unweighted Kappa coefficient for agreement in motor and sensory levels ranged from 0.68 to 0.78 (P<0.01). There was no difference in ASIA impairment grades derived from the two examiners' results.

CONCLUSIONS

Our study results showed very good levels of agreement in ASIA clinical examinations between two experienced examiners. The established degree of variability due to inter-rater differences should be taken into account in study design of clinical trials with more than one assessor..

Perceptual threshold to cutaneous electrical stimulation in patients with spinal cord injury

STUDY DESIGN

Prospective experimental.

OBJECTIVES

The aim of this study was to develop a quantitative sensory test (QST) that could be used for assessing the level and the density (degree of impairment) of spinal cord injury (SCI) and for monitoring neurological changes in patients with SCI.

SETTING

National Spinal Injuries Centre, Stoke Mandeville Hospital, Buckinghamshire Hospitals NHS Trust, UK.

METHODS

Perceptual threshold to 3 Hz cutaneous electrical stimulation was measured in 30 control subjects and in 45 patients with SCI at American Spinal Injuries Association (ASIA) sensory key points for selected dermatomes between C3 and S2 bilaterally. Electrical perceptual threshold (EPT) was recorded as the lowest ascending stimulus intensity out of three tests at which the subject reported sensation. The level of SCI according to EPT results was established for right and left sides as the most caudal spinal segment at which patient's EPT was within the control range (mean +/- 2 standard deviation (SD)). The level of SCI, according to EPT, was then compared with clinical sensory level derived according to ASIA classification.

RESULTS

In the control group, EPT depended on the dermatome tested and was lowest for T1 (1.01 +/- 0.23 mA, mean +/- SD) and highest for L5 (3.32 +/- 1.14 mA). There was strong correlation between corresponding right and left dermatomes and between repeated assessments. In the SCI group, the level of lesion according to EPT and clinical testing was the same in 43 of the 90 tests (48%). In 37 cases (41%), the EPT level was higher than the clinical level, and in 10 cases (11%), it was lower. Below the level of lesion in incomplete SCI and in the zone of partial preservation in complete SCI, the EPT values in most dermatomes were raised compared with the control group.

CONCLUSIONS

EPT is a simple, reproducible QST that can assess both the level and the density of SCI. It seems to add sensitivity and resolution to the standard clinical testing and could be a useful adjunct in longitudinal monitoring of patients with SCI for research purposes during natural recovery and therapeutic interventions.

SPONSORSHIP

International Spinal Research Trust (ISRT), UK, Grant CLI001.

Integration of concurrent trauma registry and performance improvement programs

Health information management systems have had a tremendous impact on the delivery of healthcare. The implementation of an integrated, concurrent trauma registry and performance improvement system has had a remarkable impact on the University of Pennsylvania's trauma program. Having both the registry and performance improvement programs concurrent and integrated has allowed better utilization of staff and has produced more accurate, relevant and timely data.

Magnetic brain stimulation can improve clinical outcome in incomplete spinal cord injured patients

STUDY DESIGN

Preliminary longitudinal clinical trial.

OBJECTIVES

To test the efficacy of repetitive transcranial magnetic stimulation (rTMS) in modulating corticospinal inhibition and improving recovery in stable incomplete spinal cord injury (iSCI).

SETTING

National Spinal Injuries Centre, Stoke Mandeville Hospital, Bucks, UK and Division of Neuroscience, Imperial College Faculty of Medicine, Charing Cross Hospital, London, UK.

METHODS

Four stable iSCI patients were treated with rTMS over the occipital cortex (sham treatment) and then over the motor cortex (real treatment). Patients were assessed using electrophysiological, clinical and functional measures before treatment, during sham treatment, during the therapeutic treatment and during a 3-week follow-up period.

RESULTS

Cortical inhibition was reduced during the treatment week. Perceptual threshold to electrical stimulation of the skin, ASIA clinical measures of motor and sensory function and time to complete a peg-board improved and remained improved into the follow-up period.

CONCLUSION

In this preliminary trial, rTMS has been shown to alter cortical inhibition in iSCI and improve the clinical and functional outcome.

SPONSORSHIP

This work was supported by the International Spinal Research Trust.

Towards improved clinical and physiological assessments of recovery in spinal cord injury: a clinical initiative

Clinical practice and scientific research may soon lead to treatments designed to repair spinal cord injury. Repair is likely to be partial in the first trials, extending only one or two segments below the original injury. Furthermore, treatments that are becoming available are likely to be applied to the thoracic spinal cord to minimise loss of function resulting from damage to surviving connections. These provisos have prompted research into the improvement of clinical and physiological tests designed (1) to determine the level and density of a spinal cord injury, (2) to provide reliable monitoring of recovery over one or two spinal cord segments, and (3) to provide indices of function provided by thoracic spinal root innervation, presently largely ignored in assessment of spinal cord injury. This article reviews progress of the Clinical Initiative, sponsored by the International Spinal Research Trust, to advance the clinical and physiological tests of sensory, motor and autonomic function needed to achieve these aims.

Decreased cutaneous sensory axon-reflex vasodilatation below the lesion in patients with complete spinal cord injury

The histamine-induced skin flare response has been considered of practical value in determining the level of a spinal cord lesion, but clinical observations have varied widely with regard to the nature and degree of change below the lesion. We have quantified cutaneous sensory axon-reflex vasodilatation in patients with complete spinal cord injury (SCI) above and below the lesion, and compared the findings with normal subjects. Axon-reflex vasodilatation was induced by intradermal histamine injection, and measured by (a) laser Doppler fluxmetry and (b) tracing the surface area of the flare. Axon-reflex vasodilatation was present in all SCI patients above and below the lesion, but was significantly diminished below the lesion by both measures (pflux rise = 0.0008; pflare = 0.023), and in comparison with controls (by 39%). The flux increase was significantly correlated with the area of flare (r = 0.82; p = 0.02). Axon-reflex vasodilatation and visual analogue scale (VAS) pain scores on histamine injection were not significantly different above the lesion in SCI patients from controls. Baseline laser Doppler flux was not different at any test site in SCI and normal subjects. The cutaneous sensory axon-reflex is thus significantly diminished in SCI patients below the level of the lesion, but the underlying mechanism is unclear. A possible explanation under investigation is that increased basal or reflex sympathetic vasoconstriction mediated via the isolated spinal cord may counteract the vasodilatation produced by the cutaneous sensory terminals.

Charcot joint of the spine, a cause of autonomic dysreflexia in spinal cord injured patients

STUDY DESIGN

Case report of two subjects.

OBJECTIVE

Charcot joints of the spine as a cause of Autonomic Dysreflexia in spinal cord lesions.

SETTING

Stoke Mandeville Hospital, UK.

METHOD

Two patients with long standing spinal cord lesions developed symptoms of headaches and sweating associated with sitting up and transfers. In both cases no other cause was found to account for Autonomic Dysreflexia.

RESULT

Charcot Joints of the spine below the level of injury were demonstrated in both cases and symptoms resolved with prolonged bed rest.

CONCLUSION

As care of spinally injured patients continues to improve, they live longer and lead a more active lifestyle, it is expected that the incidence and prevalence of Charcot's joints will increase. Therefore the knowledge and heightened awareness of this entity, early diagnosis and detection with plain X-rays for urinary surveillance, may reduce the morbidity in spinal cord injured patients.

Organisation of the sympathetic skin response in spinal cord injury

OBJECTIVES

The sympathetic skin response (SSR) is a technique to assess the sympathetic cholinergic pathways, and it can be used to study the central sympathetic pathways in spinal cord injury (SCI). This study investigated the capacity of the isolated spinal cord to generate an SSR, and determined the relation between SSR, levels of spinal cord lesion, and supraspinal connections.

METHODS

Palmar and plantar SSR to peripheral nerve electrical stimulation (median or supraorbital nerve above the lesion, and peroneal nerve below the lesion) were recorded in 29 patients with SCI at various neurological levels and in 10 healthy control subjects.

RESULTS

In complete SCI at any neurological level, SSR was absent below the lesion. Palmar SSR to median nerve stimuli was absent in complete SCI with level of lesion above T6. Plantar SSR was absent in all patients with complete SCI at the cervical and thoracic level. In incomplete SCI, the occurrence of SSR was dependent on the preservation of supraspinal connections. For all stimulated nerves, there was no difference between recording from ipsilateral and contralateral limbs.

CONCLUSIONS

No evidence was found to support the hypothesis that the spinal cord isolated from the brain stem could generate an SSR. The results indicate that supraspinal connections are necessary for the SSR, together with integrity of central sympathetic pathways of the upper thoracic segments for palmar SSR, and possibly all thoracic segments for plantar SSR.

Defining the learning curve for the Focused Abdominal Sonogram for Trauma (FAST) examination: implications for credentialing

Focused Abdominal Sonogram for Trauma (FAST) examination is being used increasingly for the torso evaluation of injured patients. In a controlled setting using peritoneal dialysis patients as models for injured patients with free fluid we hypothesized that more experienced providers would perform FAST with greater accuracy. Twelve fellow or attending level trauma surgeons, two radiologists, and one ultrasound technician were studied for their ability to detect intraperitoneal fluid (0-1600 cm3) in nine peritoneal dialysis patients with two different volumes of dialysate/patient. FAST experience with injured patients was defined as minimal (<30 patients examinations), moderate (30-100), or extensive (>100). All surgeons had participated in a didactic/practical course before the study. Test results were reported as "+" or "-" by the participant; "+" results were further quantified by volume. The sensitivity of those in the minimal-, moderate-, and extensive-experience to detect <1 L was 45, 87, and 100 per cent, respectively; the accuracy in detecting dialysate volume within 250 cm3 was 38, 63, and 90 per cent, respectively. In this controlled setting the accuracy of FAST particularly in diagnosing smaller volumes, as well as the ability to quantify volume, improves with experience. The learning curve for FAST starts to flatten out at 30 to 100 examinations. Training and credentialing policies should consider these findings to optimize patient care.

Ultrasound and other imaging technologies in the intensive care unit

As technology advances, more imaging and procedures are performed at the bedside on critically ill patients in ICUs, thereby eliminating the risks of transporting patients. These imaging techniques can serve as diagnostic and therapeutic tools in treating the acute and chronic consequences of injured, critically ill patients. One area of growth is ultrasonography. Critical care applications of ultrasonography are expanding, and the learning curve of surgeons and intensivists performing some of these studies is improving. Ultrasonography can supplement physical examination and provide useful "real-time" information on nearly every body cavity. Other imaging technology is also available in a portable form, enabling imaging directly at the bedside. Images are now becoming readily and easily available with the advancement of teleradiology. Some of the imaging modalities are still in development, and their clinical effectiveness is being studied. In the future, more uses of these various imaging technologies may become evident and cost-effective.

Corticospinal function studied over time following incomplete spinal cord injury

STUDY DESIGN

Longitudinal.

OBJECTIVES

(1) To perform standard clinical neurological examinations and establish the pattern of clinical change with time following incomplete spinal cord injury (iSCI). (2) To establish the pattern of change in corticospinal electrophysiological function with time after iSCI. (3) To correlate clinical with electrophysiological findings.

SETTING

The National Spinal Injuries Centre, Stoke Mandeville Hospital, Aylesbury, UK and Imperial College School of Medicine, Charing Cross Hospital, London, UK.

METHODS

Neurological assessments and classification were performed according to American Spinal Injuries Association and International Medical Society of Paraplegia (ASIA/IMSOP) standards. Twenty-one patients (ages 18 - 72 years) with iSCI (level C2 - C7, ASIA impairment grades C - D) and 10 healthy control subjects (ages 27 - 57 years) were studied. Electrophysiological tests of corticospinal function were carried out using transcranial magnetic stimulation (TMS) of the motor cortex and electromyographic (EMG) recordings from thenar muscles. Both tests were performed on a number of occasions, beginning 19 - 384 days and ending 124 - 1109 days post-injury, and the group data were pooled into time epochs of 50 or 100 days post-injury for analysis. Seven of the patients were studied on seven or more occasions and were also assessed individually.

RESULTS

Individual and pooled data indicated that neurological scores improved progressively and tended to stabilise by around 300 days post-injury. When the patients were first assessed, the mean latency for motor evoked potentials (MEPs) and inhibition of voluntary EMG were significantly different from control values. There was no significant change in latency on subsequent sessions for either the grouped or individual patient data. There was no correlation between clinical assessment and electrophysiological data.

CONCLUSION

We conclude that the weakened inhibition seen following iSCI is established within a few days of the time of spinal cord trauma. We argue that reduced corticospinal inhibition may be a prerequisite for the recovery of useful motor function.

SPONSORSHIP

The work was supported by a project grant from The Wellcome Trust.

Walking index for spinal cord injury (WISCI): an international multicenter validity and reliability study

STUDY DESIGN

Construction of an international walking scale by a modified Delphi technique.

OBJECTIVE

The purpose of the study was to develop a more precise walking scale for use in clinical trials of subjects with spinal cord injury (SCI) and to determine its validity and reliability.

SETTING

Eight SCI centers in Australia, Brazil, Canada (2), Korea, Italy, the UK and the US.

METHODS

Original items were constructed by experts at two SCI centers (Italy and the US) and blindly ranked in an hierarchical order (pilot data). These items were compared to the Functional Independence Measure (FIM) for concurrent validity. Subsequent independent blind rank ordering of items was completed at all eight centers (24 individuals and eight teams). Final consensus on rank ordering was reached during an international meeting (face validation). A videotape comprised of 40 clips of patients walking was forwarded to all eight centers and inter-rater reliability data collected.

RESULTS

Kendall coefficient of concordance for the pilot data was significant (W=0. 843, P<0.001) indicating agreement among the experts in rank ordering of original items. FIM comparison (Spearman's rank correlation coefficient=0.765, P<0.001) showed a theoretical relationship, however a practical difference in what is measured by each scale. Kendall coefficient of concordance for the international blind hierarchical ranking showed significance (W=0.860, P<0.001) indicating agreement in rank ordering across all eight centers. Group consensus meeting resulted in a 19 item hierarchical rank ordered 'Walking Index for Spinal Cord Injury (WISCI)'. Inter-rater reliability scoring of the 40 video clips showed 100% agreement.

CONCLUSIONS

This is the first time a walking scale for SCI of this complexity has been developed and judged by an international group of experts. The WISCI showed good validity and reliability, but needs to be assessed in clinical settings for responsiveness.

Modulation of single motor unit discharges using magnetic stimulation of the motor cortex in incomplete spinal cord injury

OBJECTIVES

Motor evoked potentials (MEPs) and inhibition of voluntary contraction to transcranial magnetic stimulation (TMS) of the motor cortex have longer latencies than normal in patients with incomplete spinal cord injury (iSCI) when assessed using surface EMG. This study now examines the modulation of single motor unit discharges to TMS with the aim of improving resolution of the excitatory and inhibitory responses seen previously in surface EMG recordings.

METHODS

A group of five patients with iSCI (motor level C4-C7) was compared with a group of five healthy control subjects. Single motor unit discharges were recorded with concentric needle electrodes from the first dorsal interosseus muscle during weak voluntary contraction (2%-5% maximum). TMS was applied with a 9 cm circular stimulating coil centred over the vertex. Modulation of single motor unit discharges was assessed using peristimulus time histograms (PSTHs).

RESULTS

Mean (SEM) threshold (expressed as percentage of maximum stimulator output (%MSO)) for the excitatory peak (excitation) or inhibitory trough (inhibition) in the PSTHs was higher (p<0.05) in the patients (excitation = 47.1 (5.9) %MSO; inhibition = 44.3 (3.2) %MSO) than in controls (excitation=31.6 (1.2) %MSO; inhibition = 27.4 (1.0) %MSO). Mean latencies of excitation and inhibition were longer (p<0.05) in the patients (excitation=35 (1.8) ms; inhibition = 47.1 (1.8) ms) than in the controls (excitation = 21.1 (1.6) ms; inhibition = 27 (0.4) ms). Furthermore, the latency difference (inhibition-excitation) was longer (p<0.05) in the patients (10.4 (2.1) ms) than in the controls (6.2 (0.6) ms).

CONCLUSION

Increased thresholds and latencies of excitation and inhibition may reflect degraded corticospinal transmission in the spinal cord. However, the relatively greater increase in the latency of inhibition compared with excitation in the patients with iSCI may reflect a weak or absent early component of cortical inhibition. Such a change in cortical inhibition may relate to the restoration of useful motor function after iSCI.

Strategies to improve compliance with evidence-based clinical management guidelines

BACKGROUND

Clinical management guidelines (CMGs) have been developed to standardize physician practices and ensure safe and cost-effective patient care. In June 1996, evidence-based CMGs were initiated at our urban Level I trauma center. This study compares physician compliance with two such CMGs before (PRE) and after (POST) the institution of continuous surveillance by a clinical resource manager.

STUDY DESIGN

For 2 months PRE resource manager surveillance hospital records were reviewed retrospectively for compliance with two CMGs. POST data were collected prospectively for 2 months by the resource manager, who alerted practitioners to deviance from CMGs to justify or document therapy alternatives. The CMGs studied addressed deep venous thrombosis and stress ulcer prophylaxis. "Under" or "over" therapy described that which fell short of or exceeded guidelines. Data were analyzed by chi-square; p < 0.05 defined statistical significance.

RESULTS

Compliance with the CMGs was 48% PRE and 74% POST (p=0.001). All noncompliant instances POST (and none PRE) were altered or justified. Deep venous thrombosis and ulcer "over" therapy was significantly higher PRE (19% versus 2%, p=0.003; 49% versus 19%, p=0.001), resulting in $22,760.35 in costs. There was no difference in pulmonary embolism or gastrointestinal bleed rate (1%) PRE to POST.

CONCLUSIONS

The use of a clinical resource manager empowered to monitor and coordinate physician behavior improves compliance with CMGs. Further study is warranted to validate resultant outcomes benefit, specifically cost-effectiveness and duration of the need for such a program.

The effect of childhood spinal cord injury on skeletal development: a retrospective study

STUDY DESIGN

Cross-sectional clinical review.

OBJECTIVES

To assess the relationship between late spinal deformity in childhood onset spinal cord injury (SCI) and level of spinal cord lesion, severity of lesion, age at onset, duration of paralysis and pelvic deformities.

SETTING

People with spinal cord injury (onset in childhood) treated and followed up at the National Spinal Injuries Center (identified from case notes review, contacted and agreed to participate).

METHOD

One hundred and eighty-nine subjects satisfying study inclusion criteria (acute onset SCI before the 16th birthday) were identified by case note review of 8200 records. Eighty formed the group attending for clinical review including whole spine radiographs (AP and lateral). Clinical examination included neurological status and joint range of movements. Demographic data was recorded.

RESULTS

Scoliosis occurred more frequently and was more severe in those injured at a younger age, 38 degrees, compared with 24 degrees in those injured later (P<0.05), in paraplegia, 33 degrees, versus tetraplegia, 17 degrees, (P<0.01) and in complete, 36 degrees, versus incomplete lesions, 18 degrees, (P<0.001). Lordosis angulation in paraplegic subjects was significantly greater than in tetraplegic subjects in both seated, 50 degrees versus 25 degrees (P<0.014) and standing subjects 78 degrees versus 59 degrees (P<0.017) respectively and for kyphosis in standing subjects, 52 degrees versus 31 degrees (P<0.01). Sagittal measurements were influenced by habitual posture (which also corresponded to the severity of the lesion).

CONCLUSION

Younger age at onset was shown to be associated with more severe scoliosis, as has been reported by others. Subjects with paraplegia and complete lesions demonstrated a greater and more frequently occurring scoliosis than those with tetraplegia and incomplete lesions respectively. Lordosis was greater in those with paraplegia than with tetraplegia and in those with very incomplete lesions compared with complete lesions. However the influence of the severity of the lesion cannot be separated from the postural position when analyzing spinal deformity.

Motor unit discharge characteristics during voluntary contraction in patients with incomplete spinal cord injury

Synchronisation of motor unit discharges is commonly seen in hand muscles of normal man but is absent following neurologically complete spinal cord injury and reduced after stroke. These findings support the notion that some corticospinal inputs to motoneurones are shared and contribute to the observed synchrony of discharge. In this study we have examined motor unit discharge in hand muscles below the level of an incomplete spinal cord injury in an attempt to relate strength of synchrony to the integrity of the corticospinal tract. Eight patients with incomplete spinal cord injury (neurological level C3-C7) and eight control subjects took part in the study. The patients had sustained injury 14-191 weeks prior to the recordings and had since regained good motor function in their hands. Two concentric needle electrodes were inserted into the first dorsal interosseus muscle which subjects were instructed to contract weakly so that potentials from individual motor units could be reliably identified on both recordings. Synchrony was detected by constructing cross-correlograms between the discharges of pairs of individual motor units. The amount of synchronous firing was determined from the magnitude of any peak in the cross-correlogram, as the probability above chance (XP) of one motor unit firing with respect to the other and vice versa. The degree of synchrony was lower (P < 0.05) in the patient group (mean XP 0.06) than in the control group (mean XP 0.09). The incidence of significant synchrony was lower in the patient group (41.8 %) than in the control group (92.9 %). The mean (+/- S.E.M.) frequency of motor unit discharge was slightly lower (P < 0.05) in patients (9.7 +/- 0.4 impulses s-1) than controls (10.8 +/- 0.5 impulses s-1). The mean width of synchrony peaks was narrower (P < 0.05) in patients (11.4 +/- 1.1 ms) than controls (13.2 +/- 0.6 ms). We conclude that the weaker synchrony of motor unit discharge in incomplete spinal cord injury may reflect permanent damage to some corticospinal axons.

Comparison of input-output patterns in the corticospinal system of normal subjects and incomplete spinal cord injured patients

We have examined input-output patterns in the corticospinal system after incomplete spinal cord injury. The amplitude of the motor evoked potential (MEP) to transcranial magnetic stimulation (TMS) was used to study the patterns of recruitment, with increasing stimulus intensity, and facilitation, with increasing voluntary contraction, in thenar muscles of 12 patients with incomplete spinal cord injuries and 13 control subjects. The patients had all suffered spinal cord injury at a segmental level rostral to C8 and T1, the segments supplying innervation of thenar muscles. The patients showed a less pronounced increase in MEP amplitude with increasing strength of TMS compared with the controls. Specifically, at a stimulus strength of 120% threshold and above, the patients showed significantly smaller MEPs relative to the maximum ulnar nerve M-wave response than the controls. The patients also showed a less steep pattern of facilitation with voluntary drive. The MEP continued to increase up to 50% maximum voluntary contraction (MVC) whereas the controls reached a plateau around 10% MVC. The results indicate that the patients show modified corticospinal recruitment and facilitation of the motoneurone pool. We speculate that the function of the adapted corticospinal system after spinal cord injury might be to regulate and modulate drive to motoneurones originating from segmental and other descending inputs. We discuss how such a modified corticospinal system might be of functional benefit to the patients.

The human motor cortex after incomplete spinal cord injury: an investigation using proton magnetic resonance spectroscopy

OBJECTIVES

(1) A biochemical investigation of the motor cortex in patients with incomplete spinal cord injury and normal control subjects using proton magnetic resonance spectroscopy (MRS). (2) To relate any altered biochemistry with the physiological changes in corticospinal function seen after spinal cord injury.

METHODS

A group of six patients with incomplete spinal cord injury who showed good recovery of motor function were selected. The patients were compared with five healthy control subjects. Electromyographic (EMG) responses of thenar muscles to transcranial magnetic stimulation (TMS) of the motor cortex showed that inhibition of cortical output was weaker in the patients than the controls. Proton MRS data were collected from a plane at the level of the centrum semiovale. Two 4.5 cm3 voxels in the motor cortex and a third voxel in the ipsilateral occipital cortex were examined in the patients and control subjects.

RESULTS

The mean level of N-acetylaspartate (NAA), expressed relative to the creatine (Cr) peak (NAA/Cr), was significantly increased in the motor cortex of the patients compared with their ipsilateral occipital cortex or either cortical area in the controls. No differences between patients and controls were seen for any of the other metabolite peaks (choline (Cho), glutamate/glutamine (Glx) or the aspartate component of NAA (AspNAA)) relative to Cr. Choline relative to Cr (Cho/Cr) was higher in the motor cortex of the control subjects than in their ipsilateral occipital cortex. This difference was not present in the patients.

CONCLUSIONS

Raised NAA/Cr in the motor cortex of the patients probably results from increased NAA rather than a decrease in the more stable Cr. The possible relevance of a raised NAA/Cr ratio is discussed, particularly with regard to the changed corticospinal physiology and the functional recovery seen in the patients.

Responses of thenar muscles to transcranial magnetic stimulation of the motor cortex in patients with incomplete spinal cord injury

OBJECTIVE

To investigate changes in electromyographic (EMG) responses to transcranial magnetic stimulation (TMS) of the motor cortex after incomplete spinal cord injury in humans.

METHODS

A group of 10 patients with incomplete spinal cord injury (motor level C3-C8) was compared with a group of 10 healthy control subjects. Surface EMG recordings were made from the thenar muscles. TMS was applied with a 9 cm circular stimulating coil centred over the vertex. The EMG responses to up to 50 magnetic stimuli were rectified and averaged.

RESULTS

Thresholds for compound motor evoked potentials (cMEPs) and suppression of voluntary contraction (SVC) elicited by TMS were higher (p < 0.05) in the patient group. Latency of cMEPs was longer (p < 0.05) in the patient group in both relaxed (controls 21.3 (SEM 0.5) ms; patients 27.7 (SEM 1.3) ms) and voluntarily contracted (controls 19.8 (SEM 0.5) ms; patients 27.6 (SEM 1.3) ms) muscles. The latency of SVC was longer (p < 0.05) in the patients (51.8 (SEM 1.8) ms) than in the controls (33.4 (SEM 1.9) ms). The latency difference (SVC-cMEP) was longer in the patients (25.3 (SEM 2.4) ms) than in the controls (13.4 (SEM 1.6) ms).

CONCLUSION

The longer latency difference between cMEPs and SVC in the patients may reflect a weak or absent early component of cortical inhibition. Such a change may contribute to the restoration of useful motor function after incomplete spinal cord injury.

The impact of true partnership between a university Level I trauma center and a community Level II trauma center on patient transfer practices

OBJECTIVE

To examine the effect of a clinical and administrative partnership with an academic urban Level I trauma center on the patient transfer practices at a suburban/rural Level II center.

METHODS

Data for 2 years before affiliation (PRE) abstracted from inpatient charts and the trauma registry were compared with that for 2 years after (POST). The following data were collected: number of, reason for, and destination and demographics of transfers. Chi(2) test and t test analyses were used; p < 0.05 defined significance; data are mean +/- SEM.

RESULTS

Transfer rate increased from 4% PRE to 6.9% (p = 0.001) POST with no significant difference in age, Glasgow Coma Scale score, Injury Severity Score, or Revised Trauma Score. Repatriation occurred in 12.8% POST (none PRE). The current Level I facility accepted 1.8% of all transfers PRE and 36.4% POST (p = 0.0001). PRE/POST rates by reason are as follows: pediatric, 14.6%/9.0% (p = 0.04); intensive care unit, 0.4%/1.7% (p = 0.13); complex orthopedic, 100%/0% (p = 0.005); vascular, 50%/0% (p = 0.008); spinal cord injury, 100%/100%; and ophthalmologic, 0%/100% (p = 0.005).

CONCLUSIONS

In this experience of Level I/II partnership (1) transfer patterns were altered, (2) select patient cohort transfers decreased (pediatric, complex orthopedic, vascular), whereas others increased (aortic work-up), and (3) repatriation rates were low.

Long-term survival in spinal cord injury: a fifty year investigation

The aims of this study were to examine long-term survival in a population-based sample of spinal cord injury (SCI) survivors in Great Britain, identify risk factors contributing to deaths and explore trends in cause of death over the decades following SCI. Current survival status was successfully identified in 92.3% of the study sample. Standardised mortality ratios (SMRs) were calculated and compared with a similar USA study. Relative risk ratio analysis showed that higher mortality risk was associated with higher neurologic level and completeness of spinal cord injury, older age at injury and earlier year of injury. For the entire fifty year time period, the leading cause of death was related to the respiratory system; urinary deaths ranked second followed by heart disease related deaths, but patterns in causes of death changed over time. In the early decades of injury, urinary deaths ranked first, heart disease deaths second and respiratory deaths third. In the last two decades of injury, respiratory deaths ranked first, heart related deaths were second, injury related deaths ranked third and urinary deaths fourth. This study also raises the question of examining alternative neurological groupings for future mortality risk analysis.

Evaluating neurological group homogeneity in assessing the mortality risk for people with spinal cord injuries

A study of 3178 individuals injured in Britain between 1943 and 1990 and surviving the first year post-injury was conducted to evaluate the homogeneity of mortality risk ratios within groups based on varying degrees of neurological injury level and completeness of the injury. The study shows that it is less than optimal to combine individuals into neurological groupings of C1-C4 ABC, C5-C8 ABC and T1-S5 ABC since the risk ratios are not homogeneous within these groups. Similarly, combining individuals into neurological groupings of tetraplegia complete, tetraplegia incomplete, paraplegia complete and paraplegia incomplete may not be appropriate for the same reasons. The consequence of performing a survival analysis using either of the traditional sets of groups is to dilute the risk ratios for a subset of individuals within a particular group, thereby providing less discrimination between neurological groups. Cox proportional hazards regression was employed to determine a set of neurological groupings with homogeneous risk ratios within a group while providing better differentiation between groups.

Recidivism in equestrian trauma

A 3-year chart survey and questionnaire was conducted of equestrian-injured patients at a regional trauma center to determine patterns and consequences of injury and rate of recidivism. Ninety-two patients (95 encounters) were treated; most were young (mean age, 27 +/- 11 years) women (84%) riders sustaining falls (80%). Most injuries were orthopedic (47%); 19 per cent of patients required hospital admission. There was one death. Helmet use was documented in only 34 per cent. Eighty-one per cent of patients responded to a follow-up telephone survey; 36 per cent recounted additional accidents (mean, 1.4 +/- 0.5). Mean time lost from work was 3 weeks, with 19 per cent reporting chronic disability. Mean annual hospital charges for the cohort were $88,925.00. Recidivism is common in equestrian trauma. Hospital charges are significant. Lost time from work is considerable, with one in five patients reporting long-term disability. Given the cost and disability incurred with equestrian trauma, efforts at injury prevention appear warranted.

Agitation

Agitation is a frequent clinical problem that adds significant morbidity to the hospital course. Agitation is usually part of an ambiguous constellation of cognitive and psychiatric symptoms, with a fluctuating clinical course. Observation of vastly different symptoms occurring at different times leads to misdiagnosis or underrecognition of serious underlying disorders. The most common causes of agitation include delirium, dementia, and acute psychosis. Risk factors attributable to hospitalization include pain, anxiety, and stressors endemic to intensive care. Agitated states may have multiple causes, and each potential contributor must be pursued and treated independently. Definitive diagnosis is dependent on a comprehensive history, patient observation, physical examination, and selective diagnostic studies.

Hypothermia

Hypothermia in the hospitalized adult may be a primary process, as in exposure, or a result of a multitude of disease processes or iatrogenic factors. The condition affects virtually every metabolic process in the body. A thorough understanding of the pathophysiology of hypothermia enables the clinician to differentiate between the hypothermic syndrome and underlying illness and can assist in the detection and management of clinical sequelae. A reliable patient history is the most helpful diagnostic tool, but careful physical examination and laboratory studies are also important for detection of primary or secondary illness.

Cardiovascular and hormonal responses to food ingestion in humans with spinal cord transection

In sympathetic denervation due to primary autonomic failure, ingestion of food causes a fall in blood pressure (BP) and exacerbates postural hypotension. It is not known whether these responses occur in tetraplegics with physiologically complete cervical spinal cord transection, who also have sympathetic dysfunction because of disruption of descending spinal sympathetic pathways. We, therefore, studied the effect of a liquid meal on BP, heart rate (HR) and neurohormonal levels in tetraplegics. Paraplegics with low lesions and without sympathetic dysfunction served as controls. After food ingestion, there was no fall in BP in tetraplegics or in controls. HR did not change in either group. After fund, plasma noradrenaline was unchanged in tetraplegics, but rose in controls, while plasma renin activity (PRA) rose in tetraplegics but not in controls. The fall in BP and rise in HR on head-up tilt after the meal in tetraplegics was similar to that before the meal. There was no change in PRA following pre-prandial tilt in either group; post-prandial tilt raised levels in the tetraplegics, unlike in controls. Thus there is considerable variance in the responses to food between tetraplegics and paraplegic controls, and even greater differences when compared with published data in other autonomic disorders with sympathetic dysfunction; this may relate to the site and the nature of the sympathetic lesion and the ability to activate compensatory mechanisms.

Neurological issues

The case histories of two patients who had had a spinal cord injury (SCI) were selected by the senior author and sent to four experts in the field of SCI. Based on the 1992 American Spinal Injury Association (ASIA) and International Medical Society of Paraplegia (IMSOP) standards, the four participants plus the senior author recorded the motor and sensory scores, the ASIA impairment scale (AIS), the neurological level (NL) and the zone of partial preservation (ZPP). Several minor scoring errors occurred among the participants, especially with motor scores when key muscles could not be tested due to pain, or external immobilization devices. Difficulties with interpretation occurred with the motor levels and the ZPP for the patient with a complete injury. This exercise points to the need for all examiners of SCI patients to thoroughly familiarize themselves with the standards and to use the motor and sensory scores to arrive at a NL and ZPP. They also indicate a need to revise the standards to clarify the determination of sensory levels and how to score muscles whose strength is inhibited by pain.

Diaspirin cross-linked hemoglobin is efficacious in gut resuscitation as measured by a GI tract optode

The objective of this study was to compare the efficacy of diaspirin cross-linked hemoglobin (DCLHb) with that of standard resuscitative fluids in restoring intestinal mucosal oxygenation and villous architecture after hemorrhage. Male rats were bled to a base deficit of 5 +/- 2 nmol/l under propofol anesthesia and monitored for 90 minutes postresuscitation with DCLHb, blood, lactated Ringer's solution, albumin, or nothing (DNR) for mucosal oxygen tension (Pmo2) and physiologic and laboratory parameters. Small intestinal histologic specimens were obtained and scored independently by two investigators blinded to therapy on a scale of 0 (normal) to 4 (worst). All treatments restored Pmo2; only DCLHb did so without exceeding baseline values. For untreated rats (DNR), Pmo2 was not restored. Normal mucosal architecture was maintained only in DCLHb-treated rats. As Pmo2 increased, mucosal score improved. In a rat model of controlled hemorrhage, Pmo2 changes measured by an optode correlated with gut histological abnormalities. By these criteria, DCLHb is superior to crystalloid, colloid, and blood in gut resuscitation.

A prospective study of surgeon-performed ultrasound as the primary adjuvant modality for injured patient assessment

Ultrasound diagnostic imaging, having been used in Germany in the trauma setting for more than 15 years, has unique qualities that give it distinct advantages over other tests (DPL, CT), and is gradually gaining acceptance by surgeons in the United States. In this prospective study, experienced surgeon sonographers successfully used ultrasound as the primary adjuvant modality to detect hemoperitoneum and pericardial effusion in injured patients. The ultrasound evaluations of 371 patients demonstrated that in 65 patients with significant injuries, ultrasound detected 53, that is, had an 81.5% sensitivity and 99.7% specificity. They conclude that ultrasound should be the primary adjuvant instrument for the evaluation of injured patients because it is rapid, accurate, and is potentially cost-effective.

Minimizing admission laboratory testing in trauma patients: use of a microanalyzer

OBJECTIVE

Routine admission laboratory test protocols in injured patients are costly and involve excessive phlebotomy and turnaround time. The purpose of this prospective study was to evaluate the utility of (1) a microanalyzer, NOVA-SP5 (which provides rapid results on minimal blood volume), and (2) each component of our standard laboratory test battery.

METHODS

Laboratory test results for 200 consecutive injured patients admitted to a level I trauma center were evaluated by paired sample analysis. Our standard battery [60 mL: ($348): type and screen, complete blood count, PT/PTT, electrolytes, BUN, creatinine, glucose, calcium, amylase, ethanol level, and arterial blood gas] run "stat" in the central laboratory was compared to the microanalyzer profile [< 1 mL: ($182): hemoglobin, hematocrit, electrolytes, glucose, Ca2+, and arterial blood gas] run by the trauma team in the resuscitation area. Patient data and laboratory turnaround time (from time of admission to time results obtained) were recorded. Data were analyzed by linear regression.

RESULTS

Components of the paired samples correlated well (r2 0.78 to 0.99). Turnaround times were 64 (+/- 3) and 6 (+/- 1) minutes for standard analysis and microanalysis, respectively. Only two of the 26 patients requiring emergent surgical procedures had standard results available preoperatively. These patients had twice as many laboratory abnormalities as the remainder. Minimal diagnosis or intervention resulted from those values exclusive to standard analysis (white blood count, amylase, ethanol level, BUN, creatinine, platelet count, PT, and PTT). Six of ten abnormal BUN or creatinine results normalized, including two values in patients who received contrast for portable intravenous pyelography, and in all patients without a history of hypertension or diabetes. Platelet count and PT/PTT were normal in 85% of non-head-injured patients, compared with 58% of those with GCS score < or = 8.

CONCLUSIONS

Microanalysis is accurate, expedient, conserves blood, and is sufficient for evaluation of most trauma patients. Those with hypertension, diabetes, or severe head trauma may require additional testing. Routine use of this technique could reduce cost substantially ($16,000/100 patients). The role of microanalysis in follow-up laboratory evaluation of injured patients remains to be elucidated.

Indications for obtaining surveillance thoracic and lumbar spine radiographs

The purpose of this study was to identify risk factors for thoracic/lumbar spine fractures in patients with blunt injuries and subsequently establish indications for obtaining surveillance thoracolumbar radiographs. Retrospective review of all patients with blunt injuries (n = 1485) admitted in 1992 to a level I trauma center with a discharge diagnosis of thoracolumbar spine fracture established entrance criteria for a 4-month prospective study. Relative risk of fracture (RR) was calculated. Retrospective. Seventy-six percent (176 of 233) had radiographs; 21% had fractures; one diagnosed late. Prospective. One hundred percent (167 of 167) had radiographs; 9% (15 of 167) had fractures; none diagnosed late or missed. Forty percent (26 of 65) of patients with fractures had no pain or tenderness; 35% (9) required surgical spinal fixation. Our data define these indications for obtaining thoracolumbar radiographs in patients with blunt injuries: back pain (RR1), fall > or = 10 feet, ejection from motorcycle/motor vehicle crash > or = 50 mph, GCS score < or = 8, (all RR2), and neurologic deficit (RR10). The sensitivity of our surveillance radiography protocol has increased to 100%. The absence of back pain does not exclude significant thoracolumbar trauma.

Increased hypoxic ventilatory sensitivity during exercise in man: are neural afferents necessary?

1. The acute ventilatory response to 3 min periods of hypoxia (AHR) was examined in nine patients with clinically complete spinal cord transection (T4-T7) during (a) rest and (b) electrically induced leg exercise (EEL). 2. EEL was produced by surface electrode stimulation of the quadriceps muscles so as to cause the legs to extend at the knee against gravity. End-tidal PCO2 was held constant 1-2 mmHg above resting values throughout both protocols. 3. On exercise, the average increase in metabolic CO2 production (VCO2 +/- S.E.M.) was 41 +/- 5 ml min-1. Venous lactate levels did not rise with exercise. 4. Baseline euoxic ventilation did not increase significantly with EEL, but there was a consistent and highly significant increase in the ventilatory response to hypoxia during EEL (mean delta AHR +/- S.E.M. of 1.6 +/- 0.21 min-1). 5. We conclude that an increase in hypoxic sensitivity during exercise can occur in the absence of volitional control of exercise and in the absence of afferent neural input from the limbs.

Mortality, morbidity, and psychosocial outcomes of persons spinal cord injured more than 20 years ago

Mortality, morbidity, health, functional, and psychosocial outcomes were examined in 834 individuals with long term spinal cord injuries. All were treated at one of two British spinal injury centres: the National Spinal Injuries Centre at Stoke Mandeville Hospital or the Regional Spinal Injuries Centre in Southport; all were 20 or more years post injury. Using life table techniques, median survival time was determined for the overall sample (32 years), and for various subgroups based on level and completeness of injury and age at injury. With the number of renal deaths decreasing over time, the cause of death patterns in the study group as it aged began to approximate those of the general population. Morbidity patterns were found to be associated with age, years post injury, or a combination of these factors, depending upon the particular medical complication examined. A current medical examination of 282 of the survivors revealed significant declines in functional abilities associated with the aging process. Declines with age also were found in measures of handicap and life satisfaction, but three quarters of those interviewed reported generally good health and rated their current quality of life as either good or excellent.

Hemodynamic and neurohormonal effects of clonidine in patients with preganglionic and postganglionic sympathetic lesions. Evidence for a central sympatholytic action

BACKGROUND

Clonidine, a partial presynaptic and postsynaptic alpha-adrenoceptor agonist, has been shown to lower blood pressure in normal subjects but not in tetraplegics; however, the mechanisms of this action have not been elucidated.

METHODS AND RESULTS

The hemodynamic and hormonal basis of the hypotensive action of clonidine was investigated in tetraplegics with complete cervical spinal cord transection and preganglionic sympathetic denervation, in patients with unilateral brachial plexus injury and postganglionic sympathetic denervation, and in normal subjects. In normal subjects, the fall in blood pressure after clonidine infusion was accompanied by a reduction in cardiac output that was predominantly due to a fall in stroke volume and in heart rate. The lack of fall in blood pressure, cardiac output, and stroke volume in tetraplegics indicates that these effects are exerted at a supraspinal level and require intact descending sympathetic pathways. After clonidine infusion, digital skin vasodilatation occurred in normal subjects, in the innervated but not the denervated limb of patients with unilateral brachial plexus injury, and in tetraplegics, indicating that this response is due to the central sympatholytic effect of clonidine. Plasma norepinephrine was much lower in tetraplegics compared with normal subjects, and after clonidine infusion, it fell substantially in normal subjects alone. Plasma renin activity did not change. Bladder stimulation in tetraplegics resulted in a rise in blood pressure and vasoconstriction in digital skin vessels. The inability of clonidine to significantly reduce or abolish the pressor and digital vasoconstrictor responses after bladder stimulation in tetraplegics indicates that clonidine does not exert a major effect on spinal preganglionic neurons or peripheral presynaptic alpha 2-adrenoceptors.

CONCLUSIONS

Therefore, clonidine is a suitable drug for use in analyzing the central supraspinal levels of control in varying circulatory disorders, such as hypertension and postural hypotension.

Wound healing and T-lymphocytes

T-cell depletion leads to impaired wound healing. We studied the effect of combined T-helper and T-suppressor lymphocyte depletion on wound healing and compared it with the effect of all T-cell depletion. Groups of 10 male balb/c mice, 8 weeks old, underwent a 2.5-cm skin incision and subcutaneous implantation of polyvinyl alcohol sponges. Twenty-four hours prior to wounding one group was treated with 3OH12, a rat anti-mouse monoclonal antibody against the Thy-1.2 antigen present on all T-cells (1 mg); another group received 1 mg each of GK1.5 (anti-L3T4, CD4; anti-helper/effector subset) and 2.43 (anti-Lyt 2.1, CD8; anti-suppressor/cytotoxic subset). All monoclonal antibodies are cytotoxic in vivo. Controls received 1 mg of nonspecific rat IgG. Treatments were repeated weekly. Animals were sacrificed at 2 and 4 weeks postwounding. Equal depletion of all T- and Th- and Ts-subsets in peripheral blood and spleens was noted in the two experimental groups at sacrifice. Depleting Thy-1.2 cells (all T-cells) impaired wound healing as assessed by wound breaking strength and collagen synthesis. Combined anti-T-helper/effector and T-suppressor/cytotoxic depletion resulted in improved wound-healing parameters. This suggests that there is a Thy-1.2+, L3T4-, Lyt2- subpopulation of T lymphocytes which normally stimulates wound healing.

Inhibition of wound repair by thymic hormones

To further define the role of the thymus in wound healing, we studied the effects of two thymic hormones on fibroplasia in normal euthymic and in nude athymic mice. Groups of 10 mice underwent a 2.5 cm dorsal skin incision with subcutaneous placement of polyvinyl alcohol sponges. Starting on the day of wounding, the following daily injections were given: (1) thymopentin (TP5), an active synthetic pentapeptide of thymopoietin, a naturally occurring thymic hormone (1 microgram/day/IM); (2) thymulin or facteur thymique serique (FTS), a naturally occurring circulating thymic hormone (0.2 microgram/day/IM); (3) control saline solution (0.1 ml/day/IM). All mice were killed 4 weeks after wounding, and wound breaking strength and hydroxyproline content of the sponge granulomas were measured. The results show that both thymic hormones impaired wound breaking strength and reparative collagen synthesis in normal and athymic mice. The magnitude of the wound healing impairment induced by the two hormones was equal in the thymus-bearing and in the nude mice. The data support previous findings, which suggested that the thymus has an inhibitory effect on wound healing.

Haemodynamic, hormonal and urinary responses to postural change in tetraplegic and paraplegic man

We have studied the haemodynamic, hormonal and urinary effects of postural change in 6 tetraplegic patients, 6 paraplegic patients and 6 normal subjects. Measurements of blood pressure and heart rate, plasma renin activity, plasma aldosterone, urine volume and electrolyte excretion were made for 60 minutes while sitting and 60 minutes while recumbent. In tetraplegics the blood pressure was lower when sitting and rose during recumbency, unlike paraplegics and normal subjects. Plasma renin activity and aldosterone were higher in tetraplegics when sitting compared to normal subjects and did not fall during recumbency. Urine output increased significantly after recumbency in tetraplegics, but not in paraplegics or normal subjects. Both urinary sodium and potassium excretion were lower in tetraplegics and higher in paraplegics compared to normal subjects when sitting. In paraplegics the fall in both sodium and potassium excretion did not appear to be related to change in posture. Our observations indicate that recumbency induces a diuresis in tetraplegics but not in paraplegics or in normal subjects. The diuresis in tetraplegics may be related to the accompanying haemodynamic and hormonal changes induced by recumbency.

Haemodynamic actions of clonidine in tetraplegia--effects at rest and during urinary bladder stimulation

We studied the haemodynamic effects of clonidine (2 micrograms/kg/iv) in 7 tetraplegics and 7 normal subjects. Measurements of blood pressure, stroke volume, cardiac output and digital (finger) skin blood flow were made before and after clonidine for 60 minutes. Blood pressure, stroke volume and cardiac output did not fall in tetraplegics, unlike normals. Resting digital skin blood flow was higher in tetraplegics and fell after clonidine. In normal subjects however, an increase in digital skin blood flow occurred after clonidine. The pressor and digital vasoconstrictor responses to bladder stimulation were attenuated after clonidine. The inability of clonidine to induce a fall in blood pressure, stroke volume, cardiac output and cause peripheral vasodilation in tetraplegics is consistent with its central sympatholytic effects. Attenuation of the responses to bladder stimulation suggest an effect on spinal sympathetic neurones.

Vascular effects of clonidine in patients with tetraplegia and unilateral brachial plexus injury

Evidence from studies in both animals and in tetraplegics with complete cervical spinal cord transection and preganglionic lesion, indicates that clonidine lowers blood pressure predominantly by a centrally mediated action. We have investigated the haemodynamic basis of this action and performed additional studies in patients with unilateral brachial plexus injury and postganglionic lesions, to further determine the site and mechanism of its action. Blood pressure fell after clonidine in normal subjects but not in tetraplegics. In normal subjects, the fall in blood pressure was associated with a fall in cardiac output, due to a fall in both heart rate and stroke volume. Digital skin vasodilatation occurred after clonidine in normal subjects and only in the innervated limb in patients with unilateral brachial plexus injury. In tetraplegics and in the denervated limb in unilateral brachial plexus injury, there was no vasodilatation; instead a vasoconstrictor response occurred, due to the peripheral adrenoceptor action of clonidine. We conclude that the fall in blood pressure and cardiac output in normal subjects after clonidine were due to its central sympatholytic action. Digital skin vasodilatation after clonidine in normal subjects and the innervated limb in unilateral brachial plexus injury was due to the withdrawal of vasoconstrictor tone and requires intact descending sympathetic pathways.

Neuroendocrine control of vasopressin secretion and its effect on blood pressure in subjects with spinal cord transection

The osmotic and cardiovascular control of arginine vasopressin (AVP) secretion, and the effect of this hormone on cardiovascular regulation were assessed both in normal controls and in subjects with tetraplegia. Infusion of hypertonic saline caused a marked rise in blood pressure in the tetraplegics but not in the normal controls. Head-up tilt resulted in a greater AVP response in the tetraplegics than in the controls because of the additional hypotensive response in the tetraplegics. Infusion of AVP itself at physiological concentrations had little effect on blood pressure in the normal subjects but resulted in a marked rise in blood pressure in the tetraplegics. Tetraplegics therefore show appropriate release of AVP to both osmotic and cardiovascular stimuli but increased sensitivity to the pressor effects of this hormone.

Renal vascular responses to saralasin in conscious chemically denervated rabbits and patients with tetraplegia

To determine the relative contributions of direct angiotensin-II-like myotropism and sympathetic nerve stimulation to the partial agonist effect of saralasin, the renal vascular responses to i.v. saralasin (5, 10, 20 micrograms/kg/min) were assessed in normal conscious rabbits before and after sympatholytic treatment with guanethidine (24 mg/kg/day for 9 days) and in 6 chronic tetraplegic patients (0.5, 1, 5 micrograms/kg/min) before and after alpha-adrenoreceptor blockade with i.v. thymoxamine (1 mg/kg/h). In rabbits saralasin reduced effective renal plasma flow (ERPF) and glomerular filtration rate (GFR), and increased renal vascular resistance (RVR) without affecting mean arterial blood pressure (BP). Responses were similar in both groups, but recovery following saralasin was more prolonged after treatment with guanethidine. When 0.1 microgram/kg/min (one fiftieth of the smallest i.v. dose) was infused just proximal to the renal arteries in 4 conscious rabbits (chronically cannulated), renal perfusion fell and RVR increased. In tetraplegics saralasin produced a transient rise in BP and variable increase in RVR; neither response being altered by thymoxamine. These results suggest that saralasin-induced renal vasoconstriction is independent of central and peripheral sympathetic activation, and is probably due to an intrinsic angiotensin-II-like myotropic action.

Physical ability in relation to anthropometric measurements in persons with complete spinal cord lesion below the sixth cervical segment

A study was undertaken to determine the ability of patients with complete tetraplegia below cervical sixth segment to transfer in relation to their anthropometric characteristics. Thirty-six chronic patients were assessed and spasticity was measured. A discriminant function analysis was carried out to assess the extent to which a number of anthropometric and anatomical variables could predict the patients' final ability to effect a transfer. Using nine of the original 23 predictor variables it is possible to correctly classify a patient's eventual ability to transfer in 92% of cases.