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Biomedical subjects

P J Kirkpatrick

Publications and source records attributed to P J Kirkpatrick.

At least 19 recordsLinked to original sources
PubMed2006

Treatment of a direct carotid-cavernous fistula in a patient with type IV Ehlers-Danlos syndrome: a novel approach.

We report a case of a 34-year-old female with type IV Ehlers-Danlos syndrome diagnosed with a carotid cavernous fistula presenting with progressive proptosis. Endovascular embolization using balloons or coils carries a high risk of complications in this group of patients, owing to the extreme fragility of the blood vessels. Initial treatment was conservative until an intracerebral haemorrhage occurred. To avoid transfemoral angiography, the ipsilateral carotid arteries and the internal jugular vein were surgically exposed for insertion of two endovascular sheaths. The patient was transferred from theatre to the angiography suite and the sheaths were used for embolization access. The fistula was closed, with preservation of the carotid artery, using Guglielmi detachable coils deployed in the cavernous sinus from the arterial and venous sides. Rapid resolution of symptoms and signs followed, which was sustained at 6-month follow-up. This technique offers alternative access for endovascular treatment, which may reduce the high incidence of mortality associated with catheter angiography in this condition.

Adult↗
PubMed2006

Decompressive craniectomy in traumatic brain injury: outcome following protocol-driven therapy.

Although decompressive craniectomy following traumatic brain injury is an option in patients with raised intracranial pressure (ICP) refractory to medical measures, its effect on clinical outcome remains unclear. The aim of this study was to evaluate the outcome of patients undergoing this procedure as part of protocol-driven therapy between 2000-2003. This was an observational study combining case note analysis and follow-up. Outcome was assessed at an interval of at least 6 months following injury using the Glasgow Outcome Scale (GOS) score and the SF-36 quality of life questionnaire. Forty-nine patients underwent decompressive craniectomy for raised and refractory ICP (41 [83.7%] bilateral craniectomy and 8 [16.3%] unilateral). Using the Glasgow Coma Scale (GCS), the presenting head injury grade was severe (GCS 3-8) in 40 (81.6%) patients, moderate (GCS 9-12) in 8 (16.3%) patients, and initially mild (GCS 13-15) in 1 (2.0%) patient. At follow-up, 30 (61.2%) patients had a favorable outcome (good recovery or moderate disability), 10 (20.48) remained severely disabled, and 9 (18.4%) died. No patients were left in a vegetative state. Overall the results demonstrated that decompressive craniectomy, when applied as part of protocol-driven therapy, yields a satisfactory rate of favorable outcome. Formal prospective randomized studies of decompressive craniectomy are now indicated.

Adolescent↗
PubMed2006

Decompressive craniectomy in traumatic brain injury: the randomized multicenter RESCUEicp study (www.RESCUEicp.com).

The RESCUEicp (Randomized Evaluation of Surgery with Craniectomy for Uncontrollable Elevation of intracranial pressure) study has been established to determine whether decompressive craniectomy has a role in the management of patients with traumatic brain injury and raised intracranial pressure that does not respond to initial treatment measures. We describe the concept of decompressive craniectomy in traumatic brain injury and the rationale and protocol of the RESCUEicp study.

Biomedical Research↗
PubMed2005

Extracellular amino acid changes in patients during reversible cerebral ischaemia.

This study investigated the changes in extracellular chemistry during reversible human cerebral ischaemia. Delayed analysis was performed on samples taken from a subgroup of patients during aneurysm surgery previously reported. Frozen microdialysis samples from 14 patients who had all undergone temporary clipping of the ipsilateral internal carotid artery (ICA) were analysed for another 15 amino acids with HPLC and for glycerol with CMA-600. Changes were characterised according to whether cerebral tissue oxygen pressure (PBO2) decreases were brief or prolonged. Brief ICA clipping (maximum duration of 16 minutes) in 11 patients was not associated with changes in amino acids or glycerol. Cerebral ischaemia, defined by a PBO2 decrease below 1.1 kPa for at least 30 minutes during ICA occlusion, occurred in 3 patients. None of whom developed an infarct in the monitored region. This prolonged reversible ischaemia was associated with transient delayed increases in gamma-amino butyric acid (GABA) as well as glutamate and glycerol, each by two-to-three folds. This study demonstrates detectable transient increases in human extracellular glutamate, GABA and glycerol during identified periods of reversible cerebral ischaemia, maximal 30-60 minutes after onset of ischaemia, but not in other amino acids detected by HPLC.

Adult↗
PubMed2005

Cerebral blood flow augmentation in patients with severe subarachnoid haemorrhage.

Following aneurysmal subarachnoid haemorrhage (SAH), cerebral blood flow (CBF) may be reduced, resulting in poor outcome due to cerebral ischaemia and subsequent stroke. Hypertonic saline (HS) is known to be effective in reducing intracranial pressure (ICP). We have previously shown a 20-50% increase in CBF in ischaemic regions after intravenous infusion of HS. This study aims to determine the effect of HS on CBF augmentation, substrate delivery and metabolism. Continuous monitoring of arterial blood pressure (ABP), ICP, cerebral perfusion pressure (CPP), brain tissue oxygen (PbO2), middle cerebral artery flow velocity (FV), and microdialysis was performed in 14 poor grade SAH patients. Patients were given an infusion of 23.5% HS, and quantified xenon computerised tomography scanning (XeCT) was carried out before and after the infusion in 9 patients. The results showed a significant increase in ABP, CPP, FV and PbO2, and a significant decrease in ICP (p < 0.05). Nine patients showed a decrease in lactate-pyruvate ratio at 60 minutes following HS infusion. These results show that HS safely and effectively augments CBF in patients with poor grade SAH and significantly improves cerebral oxygenation. An improvement in cerebral metabolic status in terms of lactate-pyruvate ratio is also associated with HS infusion.

Adult↗
PubMed2005

Detection and evaluation of intracranial aneurysms with 16-row multislice CT angiography.

AIM: The aim of this study was to assess the usefulness of 16-row multislice CT angiography (CTA) in evaluating intracranial aneurysms, by comparison with conventional digital subtraction angiography (DSA) and intraoperative findings. METHODS: A consecutive series of 57 patients, scheduled for DSA for suspected intracranial aneurysm, was prospectively recruited to have CTA. This was performed with a 16-detector row machine, detector interval 0.75 mm, 0.5 rotation/s, table speed 10mm/rotation and reconstruction interval 0.40 mm. CTA studies were independently and randomly assessed by two neuroradiologists and a vascular neurosurgeon blinded to the DSA and surgical findings. Review of CTA was performed on workstations with an interactive 3D volume-rendered algorithm. RESULTS: DSA or intraoperative findings or both confirmed 53 aneurysms in 44 patients. For both independent readers, sensitivity and specificity per aneurysm of DSA were 96.2% and 100%, respectively. Sensitivity and specificity of CTA were also 96.2% and 100%, respectively. Mean diameter of aneurysms was 6.3mm (range 1.9 to 28.1 mm, SD 5.2 mm). For aneurysms of less than 3 mm, CTA had a sensitivity of 91.7% for each reader. Although the neurosurgeon would have been happy to proceed to surgery on the basis of CTA alone in all cases, he judged that DSA might have provided helpful additional anatomical information in 5 patients. CONCLUSION: The diagnostic accuracy of 16-slice CTA is promising and appears equivalent to that of DSA for detection and evaluation of intracranial aneurysms. A strategy of using CTA as the primary imaging method, with DSA reserved for cases of uncertainty, appears to be practical and safe.

Adult↗
PubMed2005

Cerebral haemodynamic disturbances in patients with moderate carotid artery stenosis.

OBJECTIVE: Dynamic MR perfusion imaging can detect cerebral perfusion deficits resulting from severe internal carotid artery (ICA) stenosis. It is unknown, however, whether moderate ICA stenosis (50-69%) also causes haemodynamic disturbance. We investigated whether cerebral perfusion deficits were detectable in patients with moderate ICA stenosis. METHODS: Eighteen patients underwent T2* weighted cerebral MR perfusion imaging with a gadolinium based contrast agent. Differences in mean time to peak (mTTP) and relative cerebral blood volume (rCBV) between cerebral hemispheres were calculated for middle cerebral artery territory regions by a reader blinded to the angiographic and clinical findings. RESULTS: There were significant differences in mTTP between cerebral hemispheres in 15 patients with a mean inter-hemispheric delay in mTTP of 0.49 s (95% confidence intervals, 0.25 and 0.72 s) which was statistically significant ( p <0.001). In 1 patient with bilateral moderate stenosis there was no difference in mTTP. CONCLUSIONS: Moderate ICA stenosis results in significant ipsilateral cerebral perfusion delays detectable by dynamic susceptibility MRI. Follow-up studies might reveal whether these delays improve following carotid endarterectomy.

Aged↗
PubMed2004

Contrast-enhanced MR angiography for carotid disease: diagnostic and potential clinical impact.

OBJECTIVE: To compare contrast-enhanced MR angiography (CEMRA) with intra-arterial digital subtraction angiography (DSA) for evaluating carotid stenosis. METHODS: A total of 167 consecutive symptomatic patients, scheduled for DSA following screening duplex ultrasound (DUS), were prospectively recruited to have CEMRA. Three independent readers reported on each examination in a blinded and random manner. Agreement was assessed using the Bland-Altman method. Diagnostic and potential clinical impact of CEMRA was evaluated, singly and in combination with DUS. RESULTS: CEMRA tended to overestimate stenosis by a mean bias ranging from 2.4 to 3.8%. A significant part of the disagreement between CEMRA and DSA was directly caused by interobserver variability. For detection of severe stenosis, CEMRA alone had a sensitivity of 93.0% and specificity of 80.6%, with a diagnostic misclassification rate of 15.0% (n = 30). More importantly, clinical decision-making would, however, have been potentially altered only in 6.0% of cases (n = 12). The combination of concordant DUS and CEMRA reduced diagnostic misclassification rate to 10.1% (n = 19) at the expense of 47 (24.9%) discordant cases needing to proceed to DSA. An intermediate approach of selective DUS review resulted in a marginally worse diagnostic misclassification rate of 11.6% (n = 22) but with only 6.8% of discordant cases (n = 13). CONCLUSIONS: DSA remains the gold standard for carotid imaging. The clinical misclassification rate with CEMRA, however, is acceptably low to support its safe use instead of DSA. The appropriateness of combination strategies depends on institutional choice and cost-effectiveness issues.

Aged↗
PubMed2004

Multi-sequence in vivo MRI can quantify fibrous cap and lipid core components in human carotid atherosclerotic plaques.

OBJECTIVES: Risk of thrombo-embolic stroke is thought to be better reflected by carotid plaque composition than by luminal stenosis. We set out to determine whether high resolution MRI was a valid method of quantifying plaque components in vivo. DESIGN: A prospective cohort study validating in vivo MRI against histological analysis of excised carotid plaques. MATERIALS: Twenty-five recently symptomatic patients with severe internal carotid artery stenosis underwent pre-operative in vivo multi-sequence MRI of the carotid artery using a 1.5 T system. METHODS: Individual plaque constituents were characterized on axial MR images according to net signal intensities. Analysis of fibrous cap and lipid core content was quantified proportional to overall plaque area. Bland-Altman plots were generated, and intra-class coefficients computed to determine the level of agreement between the two methods and inter-observer variability. RESULTS: The intra-class correlation coefficients between two MR readers were 0.94 and 0.88 for quantifying fibrous cap and lipid core components, respectively. There was good agreement between MR and histology derived quantification of both fibrous cap and lipid core content; the mean % difference for fibrous cap was 0.75% (+/-2.86%) and for lipid core was 0.86% (+/-1.76%). CONCLUSION: High resolution carotid MRI can be used to quantify plaque components and may prove useful in risk stratification.

Aged↗
PubMed2004

Decompressive craniectomy in head injury.

PURPOSE OF REVIEW: To examine the evidence for the role of decompressive craniectomy in the management of traumatic brain injury. RECENT FINDINGS: This review highlights the importance of brain swelling and raised intra-cranial pressure (ICP) as of the one fundamental pathophysiological processes following traumatic brain injury. The role of protocol driven therapy in controlling raised intra-cranial pressure is discussed, with the staged application of medical interventions (including hypothermia and barbiturates). If these measures fail to control ICP, a surgical option - removal of the skull (decompressive craniectomy) can be considered. The evidence for this operation is reviewed in terms of data published in peer-reviewed journals since 1997. This evidence consists pre-dominantly of case series with no definitive Class I evidence and demonstrates a wide range of outcomes with no clear consensus regarding the indications for the operation. SUMMARY: Decompressive craniectomy is currently being applied in the management of traumatic brain injury with a wide range of outcomes reported in the literature. Current opinion on the role of this operation is therefore divided and it is now appropriate to proceed to prospective randomised studies.

Clinical Trials as Topic↗
PubMed2004

Late epilepsy following open surgery for aneurysmal subarachnoid haemorrhage.

OBJECTIVE: To determine the risk for late epilepsy (>2 weeks postoperatively) following aneurysmal subarachnoid haemorrhage (SAH) treated by early aneurysm clipping. DESIGN: Subgroup analysis of the East Anglian regional audit of SAH (1994-2000; n = 872) with 12 month follow up. Prophylactic anticonvulsants were not routinely prescribed unless there was a perioperative seizure. SUBJECTS: 472 patients with aneurysmal SAH undergoing surgical clipping of the aneurysm were studied. Patients presenting in WFNS grade V, with space occupying haematomas requiring emergency surgery, or with posterior circulation aneurysms, rebleeds, and surgery after 21 days were excluded. RESULTS: Late epilepsy occurred in 23 patients (4.9%). There was a correlation between the incidence of late epilepsy and both the presenting WFNS grade (p<0.05) (grade 1, 1.4%; grade 2, 3.8%; grade 3, 9.6%; grade 4, 12.5%) and the Glasgow outcome score at discharge (p<0.01) (good recovery, 2.2%; moderate disability, 5.0%; severe disability, 15.5%). There was no relation between the incidence of late epilepsy and sex or the site of the aneurysm. CONCLUSIONS: The low incidence of late epilepsy following open surgery for aneurysmal SAH supports the withholding of prophylactic anticonvulsants. Patients with poor WFNS grade and poor recovery after surgery are at increased risk and should be closely monitored.

Adolescent↗
PubMed2003

Pressure-autoregulation, CO2 reactivity and asymmetry of haemodynamic parameters in patients with carotid artery stenotic disease. A clinical appraisal.

OBJECTIVES: Patients with carotid artery stenotic disease and poor cerebral haemodynamic reserve are in increased risk of stroke. Haemodynamic reserve can be estimated by measuring cerebrovascular reactivity induced by breathing CO2 and pressure-autoregulation by analyzing spontaneous slow fluctuation in arterial pressure and MCA blood flow velocity. We evaluated the relationship between clinical status, CO2 reactivity, pressure-autoregulation and other haemodynamic variables derived from Transcranial Doppler ultrasonography in patients with carotid artery disease. METHODS: 38 patients were investigated. Arterial pressure and blood flow velocity were monitored during CO2 reactivity tests. Arterial pressure-corrected and non-corrected indices of CO2 reactivity were calculated to compare an influence of rise in arterial pressure during the test. The pressure-autoregulation index was calculated as correlation coefficient between slow waves in blood flow velocity and arterial pressure. RESULTS: The increase in CO2 produced a consistent rise in arterial pressure and blood flow velocity and weakened the pressure autoregulation. The value of pressure-corrected CO2 reactivity was lower (p<0.0001) than the non-corrected one, indicating that the rise in arterial pressure during the test tends to over-estimate CO2 reactivity. The pressure-corrected reactivity was correlated with pressure autoregulation (r=-0.46; p<0.005). Both CO2 reactivity and pressure-autoregulation index correlated with a degree of carotid artery stenosis. Side-to-side difference of TCD pulsatility index demonstrated a close relationship with the asymmetry of stenosis (r=-0.61; p<0.0002) and symptoms (r=-0.49; p<0.003). CONCLUSIONS: When calculating CO2 reactivity in patients with carotid artery disease, changes in arterial pressure should be considered. Both CO2 reactivity and pressure-autoregulation describe the magnitude of haemodynamic deficit caused by stenosis, pulsatility index expresses the asymmetry of stenosis.

Aged↗
PubMed2003

Arteriovenous malformations of the cerebral circulation that rupture in pregnancy.

Arteriovenous malformations (AVMs) have a poorly defined natural history, more so in the pregnant population. Presentation during the pregnancy is usually as a result of haemorrhage following rupture. Whether pregnancy alters the natural tendency to rupture remains controversial, but empirical data suggest that this is the case. The most important complication following rupture in pregnancy is the possibility of a subsequent re-haemorrhage. In those patients with high operative risk or inoperable lesions, a conservative management course should be adopted during the pregnancy allowing stereotactic radiosurgery or embolisation options to be pursued after delivery (see Management algorithm). Precautions during labour are recommended, biased towards caesarean section. In those patients in whom a lesion is deemed operable (low risk), surgery may improve the risks of poor outcome provided treatment risks are low. Factors such as AVM morphology, local expertise and support facilities (including those for endovascular therapy) are essential considerations if outcome is to improve on the natural history of the condition. Preoperative endovascular embolisation can be included when considering surgical excision.

Cerebral Hemorrhage↗
PubMed2003

Measurement of pulse pressure profiles in patients with trigeminal neuralgia.

Applanation tonometry is a non-invasive method of assessing the arterial blood pressure profiles in both the peripheral and systemic circulation. In this study the authors examined whether there were differences in these profiles in patients with trigeminal neuralgia. The carotid artery and derived aortic blood pressure waveforms were obtained using a pulse wave analysis system. The ratio of the pressure wave amplitude above the systolic shoulder to the total systolic blood pressure (augmentation index, AIx) was recorded. Thirty two patients with trigeminal neuralgia (16 male and 16 female) and 100 controls (50 male and 50 female) were recruited. Eleven patients had been treated by microvascular decompression, mean (SD) time from surgery 17 (24) months (range 3-86 months). For the patients with trigeminal neuralgia, the right and left carotid artery AIxs (mean (SD)) were 120.6 (21.7)% and 120.7 (19.1)% respectively. Corresponding values for the control group were 120.5 (19.3)% and 120.9 (19.5)%. The calculated AIx for the ascending aorta was 27.7 (10.1)% and 27.2 (10.5)% for the patients with trigeminal neuralgia and controls respectively. No significant differences were seen in either the right or left carotid artery (p=0.5 and p=0.6 respectively) or the derived ascending aorta (p=0.8). The results show that there does not seem to be a generalised increase in arterial stiffness in patients with trigeminal neuralgia.

Adult↗