Biomedical subjects

J D Pickard

Publications and source records attributed to J D Pickard.

At least 109 records · Page 6Linked to original sources

PubMed2001

Implementing the Galasko Report on the management of head injuries: the Eastern Region approach.

OBJECTIVES: The Royal College of Surgeons (RCS) Report on the management of patients with head injuries under the chairmanship of Professor Galasko, published in June 1999, made important recommendations that will have a profound effect on the organisation of management of head injuries and major implications for resources. The Eastern Region carried out an audit study to determine the provision of current services available, to assess the shortfall and likely resource implications for the implementation of the report and hence lay the foundations for a strategic plan for change across the region. METHODOLOGY: A series of interviews with all 20 accident and emergency (A&E) departments across the Eastern Region and the two regional neuroscience units (RNU) was undertaken. The results of the survey and the implications of the implementation were fed back to and discussed at a multidisciplinary regional seminar. RESULTS: There is considerable variation and major deficiencies in the service provision currently available for the management of head injuries in the Eastern Region. There are major deficiencies in A&E resources, care of moderate head injuries and rehabilitation and follow up of patients. There is a significant shortfall in resources for the implementation of the recommendations. CONCLUSION: There are major deficiencies in the overall management of head injuries. Although the RCS Galasko Report recommendations were agreed to be very desirable, they cannot be implemented without a large increase in resources in terms of funding, staffing and training.

Craniocerebral Trauma↗

PubMed2001

Preliminary experience of the estimation of cerebral perfusion pressure using transcranial Doppler ultrasonography.

OBJECTIVE: The direct calculation of cerebral perfusion pressure (CPP) as the difference between mean arterial pressure and intracranial pressure (ICP) produces a number which does not always adequately describe conditions for brain perfusion. A non-invasive method of CPP measurement has previously been reported based on waveform analysis of blood flow velocity measured in the middle cerebral artery (MCA) by transcranial Doppler. This study describes the results of clinical tests of the prototype bilateral transcranial Doppler based apparatus for non-invasive CPP measurement (nCPP). METHODS: Twenty five consecutive, paralysed, sedated, and ventilated patients with head injury were studied. Intracranial pressure (ICP) and arterial blood pressure (ABP) were monitored continuously. The left and right MCAs were insonated daily (108 measurements) using a purpose built transcranial Doppler monitor (Neuro Q(TM), Deltex Ltd, Chichester, UK) with software capable of the non-invasive estimation of CPP. Time averaged values of mean and diastolic flow velocities (FVm, FVd) and ABP were calculated. nCPP was then computed as: ABPxFVd/FVm+14. RESULTS: The absolute difference between real CPP and nCPP (daily averages) was less than 10 mm Hg in 89% of measurements and less than 13 mm Hg in 92% of measurements. The 95% confidence range for predictors was no wider than +/-12 mm Hg (n=25) for the CPP, varying from 70 to 95 mm Hg. The absolute value of side to side differences in nCPP was significantly greater (p<0.05) when CT based evidence of brain swelling was present and was also positively correlated (p<0.05) with mean ICP. CONCLUSION: The device is of potential benefit for intermittent or continuous monitoring of brain perfusion pressure in situations where the direct measurement is not available or its reliability is in question.

Adolescent↗

PubMed2001

Reproducibility of quantitative CT perfusion imaging.

The ability to demonstrate regions of abnormal cerebral blood flow in the setting of acute stroke is of diagnostic and prognostic importance. It may also influence therapeutic strategies. The advantage of CT perfusion imaging is its ability to give quantifiable measurements of cerebral blood flow on any modern CT machine without the need to buy specialized equipment. The aim was to assess day-to-day variability of values of cerebral blood volume obtained with this technique. Seven patients with cerebral gliomas were studied using dynamic CT perfusion imaging on two occasions, approximately 24 h apart to reduce variability from diurnal variations. Regions of interest were produced in predominately middle cerebral artery locations in both hemispheres on the first and second CT perfusion studies. Absolute values for cerebral blood flow were produced for these regions and were correlated with flows obtained in the same regions of interest on the follow-up study. The Pearson correlation coefficient obtained was 0.884. CT perfusion imaging is easily performed on conventional modern CT equipment and demonstrates little variability in measures of absolute cerebral blood flow within individuals when studied on two occasions within 24 h.

Adult↗

PubMed2001

MR diffusion tensor imaging of white matter tract disruption in stroke at 3 T.

Recent advances in MR diffusion weighted imaging (DWI) enable the identification of anisotropic white matter tracts with diffusion tensor imaging (DTI). We aimed to use a novel DTI technique to safely study patients with recent stroke in a high field (3 T) MR machine with its intrinsically higher spatial resolution and signal-to-noise ratio. Of ten patients studied, six had disruption of white matter tracts as determined by DTI. A further patient had distortion of white matter tracts around an infarct rather than actual disruption of the tracts themselves. The lack of tract destruction may imply a beneficial prognosis, information that is not available with conventional DWI.

Adult↗

PubMed2001

Age dependence of cerebrospinal pressure-volume compensation in patients with hydrocephalus.

OBJECT: The dynamics of both drainage and storage capacity become altered during the sequential pathological processes that lead to hydrocephalus. Cerebrospinal fluid (CSF) formation and drainage rate have been reported to be age dependent. The aim of this study was to investigate whether CSF compensatory parameters are dependent on age in patients who have symptoms of hydrocephalus and apparently normal intracranial pressure (ICP). METHODS: Forty-six patients who presented with ventriculomegaly, the clinical symptoms of hydrocephalus, and normal ICPs underwent a computerized CSF infusion test. Parameters used to describe CSF compensation were calculated and correlated with the age of each patient. The mean ICPs were found to be independent of the age of the patient. Resistance to CSF outflow (Rcsf), however, demonstrated a nonlinear increase with advancing age (r = -0.57; p < 0.0001) and was associated with a decrease in the CSF production rate, which also occurred with increasing age (r = 0.49; p < 0.002). Both the pulse amplitude of the ICP waveform and the slope of the amplitude-ICP regression line increased significantly with advancing age (r = 0.39; p < 0.01 and r = 0.43, p < 0.004, respectively). The nonlinear increase in the elastance coefficient indicated increasing brain stiffness, which acompanies older ages (r = -0.31; p < 0.04). CONCLUSIONS: In a study of patients with symptoms of hydrocephalus, but normal ICPs, the increase in Rcsf and decrease in CSF production were most pronounced in patients who were older than 56 years of age. This relationship was more significant than previously suggested.

Adaptation, Physiological↗

PubMed2001

Cerebral autoregulation following head injury.

OBJECT: The goal of this study was to examine the relationship between cerebral autoregulation, intracranial pressure (ICP), arterial blood pressure (ABP), and cerebral perfusion pressure (CPP) after head injury by using transcranial Doppler (TCD) ultrasonography. METHODS: Using ICP monitoring and TCD ultrasonography, the authors previously investigated whether the response of flow velocity (FV) in the middle cerebral artery to spontaneous variations in ABP or CPP provides reliable information about cerebral autoregulatory reserve. In the present study, this method was validated in 187 head-injured patients who were sedated and receiving mechanical ventilation. Waveforms of ICP, ABP, and FV were recorded over intervals lasting 20 to 120 minutes. Time-averaged mean FV and CPP were determined. The correlation coefficient index between FV and CPP (the mean index of autoregulation [Mx]) was calculated over 4-minute epochs and averaged for each investigation. The distribution of averaged mean FV values converged with the shape of the autoregulatory curve, indicating lower (CPP < 55 mm Hg) and upper (CPP > 105 mm Hg) thresholds of autoregulation. The relationship between the Mx and either the CPP or ABP was depicted as a U-shaped curve. Autoregulation was disturbed in the presence of intracranial hypertension (ICP > or = 25 mm Hg) and when mean ABP was too low (ABP < 75 mm Hg) or too high (ABP > 125 mm Hg). Disturbed autoregulation (p < 0.005) and higher ICP (p < 0.005) occurred more often in patients with unfavorable outcomes than in those with favorable outcomes. CONCLUSIONS: Autoregulation not only is impaired when associated with a high ICP or low ABP, but it can also be disturbed by too high a CPP. The Mx can be used to guide intensive care therapy when CPP-oriented protocols are used.

Adolescent↗

PubMed2000

Methylphenidate enhances working memory by modulating discrete frontal and parietal lobe regions in the human brain.

The indirect catecholamine agonist methylphenidate (Ritalin) is the drug treatment of choice in attention deficit/hyperactivity disorder (AD/HD), one of the most common behavioral disorders of childhood (DSM-IV), although symptoms may persist into adulthood. Methylphenidate can enhance cognitive performance in adults and children diagnosed with AD/HD (Kempton et al., 1999; Riordan et al., 1999) and also in normal human volunteers on tasks sensitive to frontal lobe damage, including aspects of spatial working memory (SWM) performance (Elliott et al., 1997). The present study investigated changes in regional cerebral blood flow (rCBF) induced by methylphenidate during performance of a self-ordered SWM task to define the neuroanatomical loci of the beneficial effect of the drug. The results show that the methylphenidate-induced improvements in working memory performance occur with task-related reductions in rCBF in the dorsolateral prefrontal cortex and posterior parietal cortex. The beneficial effects of methylphenidate on working memory were greatest in the subjects with lower baseline working memory capacity. This is to our knowledge the first demonstration of a localization of a drug-induced improvement in SWM performance in humans and has relevance for understanding the treatment of AD/HD.

Adrenergic Uptake Inhibitors↗

PubMed2000

Gradient preemphasis calibration in diffusion-weighted echo-planar imaging.

This article describes a method which enables fast and objective pulse-sequence-specific preemphasis calibration, using standard pulse sequences and system hardware. The method is based on a k-space measurement technique, and has been applied to single-shot, diffusion-weighted, spin-echo, echo-planar imaging (DW-SE-EPI), which is particularly sensitive to eddy-current-induced image distortions. The efficiency of the technique was demonstrated not only by the reduction of eddy-current fields to a negligible level using full preemphasis compensation, but also by the fact that adjustment of the slow time-base alone sufficed for the practical elimination of image distortions in the DW-SE-EPI images and the subsequent diffusion tensor maps (in a phantom and a human brain). By seeking to eliminate directly the effect of eddy-current-induced phase shifts during the EPI data collection, the method is free of the complications and restrictions associated with other eddy-current correction techniques for DW-SE-EPI (such as acquisition of additional calibration scans, intense postprocessing, extensive pulse-sequence modifications), making their use redundant.

Brain↗

PubMed2000

Continuous assessment of cerebral autoregulation--clinical verification of the method in head injured patients.

Previously, using transcranial Doppler ultrasonography, we investigated whether the hemodynamic response to spontaneous variations in cerebral perfusion pressure (CPP) provides reliable information about cerebral autoregulatory reserve. In the present study we have verified this method in 166 patients after head trauma. Waveforms of intracranial pressure (ICP), arterial pressure and transcranial Doppler flow velocity (FV) were captured daily over 0.5-2.0 hour periods. Time-averaged mean flow velocity (FV) and CPP were resolved. The correlation coefficient indices between FV and CPP (Mx) were calculated over 3 minutes epochs, and averaged for each investigation. An index of CBF (flow velocity diastolic to mean ratio) was calculated independently for each investigation. Mx depended on CPP (p < 0.0001) increasing to positive values when CPP decreased below 60 mm Hg. This threshold coincided with an averaged breakpoint for autoregulation, expressed by the index of CBF. Mx depended on outcome following head injury stronger than the Glasgow Coma Score on admission (ANOVA, F values 18 and 15 respectively; N = 166). In patients who died, cerebral autoregulation was disturbed during the first two days following injury. These results indicate an important role for the continuous monitoring of autoregulation following head trauma.

Blood Flow Velocity↗

PubMed2000

On-line monitoring of substrate delivery and brain metabolism in head injury.

Head injury is associated with complex pathophysiological changes in metabolism. The objective of the study was to investigate these changes by applying on-line bedside monitoring of cerebral metabolism using microdialysis. Following approval by the Local Ethics Committee and consent from the next of kin, a microdialysis catheter was inserted into the frontal cortex of patients with severe head injury. Twenty-one patients were studied for 102.3 +/- 26.9 hours (mean +/- 95% confidence interval; total 89.4 patient monitoring days). The overall cerebral glucose (mean of means) was 1.63 +/- 0.31 mM with periods of undetectable glucose recorded. The cerebral lactate and lactate/pyruvate ratio were 4.69 +/- 0.61 mM and 29.9 +/- 3.73 respectively. Patients who died (n = 4) or who were severely disabled (not proceeding to rehabilitation, n = 5) had a tendency towards lower glucose (1.39 +/- 0.35 mM), higher lactate (5.10 +/- 1.02 mM) and higher lactate/pyruvate ratios (35.5 +/- 7.67) compared to patients with good outcome (home or proceeding to rehabilitation, n = 12, glucose 1.80 +/- 0.49 mM, lactate 4.38 +/- 0.85 mM, lactate/pyruvate ratio 27.9 +/- 4.33). Trends in these metabolic parameters relating to outcome were identifiable. In the majority of patients, cerebral glutamate levels (overall mean of means 9.47 +/- 4.59 microM) were initially high and then declined to stable levels. Patients in whom the glutamate level remained elevated or in whom secondary rises in glutamate were seen had a poor outcome. The application of bedside analysis of microdialysis enables the progress of the patient to be monitored on-line. In addition to establishing trends of improving and deteriorating metabolism, the technique has the potential to monitor the effects of therapeutic manoeuvres on the biochemistry.

Adolescent↗

PubMed2000

Non-invasive cerebral perfusion pressure (nCPP): evaluation of the monitoring methodology in head injured patients.

The method of direct calculation of cerebral perfusion pressure (CPP) as the difference between mean arterial pressure and intracranial pressure (ICP) produces a number, which not always adequately expresses brain perfusion. We investigated an alternative non-invasive method, based on waveform analysis of Transcranial Doppler blood flow velocity in Middle Cerebral Arteries (MCA). 25 consecutive head injured patients, paralysed, sedated and ventilated were studied. Intracranial pressure (ICP) arterial blood pressure (ABP) were monitored continuously. The left and right MCAs were insonated daily (116 measurements) using a purpose-built transcranial Doppler monitor (Deltex Ltd, Chichester, U.K.) with software capable of the non-invasive estimation of CPP. Time averaged values of ABP, mean and diastolic flow velocities (FVm, FVd) were calculated and CPPe was computed as: ABP*FVd/FVm + 14. An absolute difference between real CPP and CPPe was less than 10 mm Hg in 82% of measurements and less than 13 mm Hg in 90% of measurements. The method demonstrated a high potential to detect both short-term and long-term changes in CPP. The method is of potential benefit for the intermittent measurement and continuous monitoring of changes in brain perfusion pressure in situations where the direct measurement of CPP is not available or its reliability is in question.

Adolescent↗

PubMed2000

Asymmetric frontal activation during episodic memory: the effects of stimulus type on encoding and retrieval.

Recent functional neuroimaging studies have suggested that the left prefrontal cortex is preferentially involved in the encoding of episodic memory whilst the right prefrontal cortex is preferentially involved in the retrieval of episodic memory, irrespective of the type (e.g. modality) of information being remembered. In the present PET activation study, a 2 x 2 design was employed to investigate the relationship between encoding and retrieval of verbal and non-verbal material in episodic memory. Accordingly, seven healthy volunteers were scanned whilst encoding and then recalling stimuli which either emphasised visual or verbal processes. When encoding and retrieval tasks were compared directly, significantly greater prefrontal activation was observed in the encoding conditions, regardless of modality, although these changes were bilaterally distributed. In contrast when the verbal and visual memory tasks were compared directly, the former was associated with rCBF changes that were predominantly located in the left lateral frontal cortex whilst the latter was associated with rCBF changes that were predominantly located in the right lateral frontal cortex. These results suggest that encoding and retrieval may actually involve similar regions of the lateral prefrontal cortex when all factors relating to the type of stimulus material (i.e. modality), are appropriately controlled.

Adult↗

PubMed2000

Linear coupling between functional magnetic resonance imaging and evoked potential amplitude in human somatosensory cortex.

The interpretation of task-induced functional imaging of the brain is critically dependent on understanding the relationship between observed blood flow responses and the underlying neuronal changes. However, the exact nature of this neurovascular coupling relationship remains unknown. In particular, it is unclear whether blood oxygen level-dependent functional magnetic resonance imaging (BOLD fMRI) responses principally reflect neuronal synaptic activity. In order to address this issue directly in humans, we measured the increase in somatosensory evoked potential amplitude and fMRI BOLD changes to increases in intensity of median nerve electrical stimulation in five healthy non-anaesthetized subjects. We found that mean N20-P22 amplitudes increased significantly with stimulus intensity in all subjects, as did fMRI BOLD percentage signal intensity change. Moreover, the intensity of the BOLD signal was found to correlate linearly with evoked potential amplitude in four of the five subjects studied. This suggests that the BOLD response correlates with synchronized synaptic activity, which is the major energy consuming process of the cortex.

Adult↗

PubMed2000

Multiparameter brain tissue monitoring--correlation between parameters and identification of CPP thresholds.

Continuous monitoring of brain interstitial gas concentrations allows direct regional evaluation of the pathophysiology of cerebral tissues. We have incorporated the Paratrend 7 (P7) multiparameter sensor into our established multimodal monitoring of head injured patients, to investigate the relationship between brain and arterial pO2, pCO2, and pH, as well as defining thresholds for cerebral perfusion pressure (CPP). A P7 sensor was inserted into the brain tissue of 40 adult head injured patients via a modified Camino bolt or triple lumen bolt. A second sensor was placed in the femoral artery for continuous monitoring of blood gases. Data signals from 19 monitored parameters were collected onto computer at the bedside for up to 14 days. No complications were seen. For individual patients the changes in brain tissue parameters showed large variations over 24 hours and the relationship between parameters varied considerably both between patients and during the period of monitoring any one individual. Changes related to periods of arterial desaturation, cerebral hypoperfusion and therapeutic manoeuvres could be seen. Good correlation was seen between brain pCO2 and arterial pCO2 (r = 0.58). Poor correlation was seen between CPP and brain pO2, and between brain pO2 and ICP. However, by grouping values for intracranial pressure (ICP) and CPP, thresholds for brain tissue pO2 were identified in 16 patients where CPP fell below 60 mmHg. No patients where CPP was always > 60 mmHg showed a significant threshold for a drop in brain pO2 (n = 16). In conclusion, the P7 shows potential as a monitor of regional brain oxygenation and for detection of potentially damaging secondary insults. The results must be interpreted whilst considering catheter position, autoregulation and systemic arterial changes for each individual.

Adolescent↗

PubMed2000

Head injury monitoring using cerebral microdialysis and Paratrend multiparameter sensors.

INTRODUCTION: Following head injury complex pathophysiological changes occur in brain metabolism. The objective of the study was to monitor brain metabolism using the Paratrend multiparameter sensor and microdialysis catheters. PATIENTS, MATERIAL AND METHODS: Following approval by the Local Ethics Committee and consent from the relatives, patients with severe head injury were studied using a triple bolt inserted into the frontal region, transmitting an intracranial pressure monitor, microdialysis (10 mm or 30 mm membrane; glucose, lactate, pyruvate, glutamate) catheter and Paratrend multiparameter (oxygen, carbon dioxide, pH and temperature) sensor. A Paratrend sensor was also inserted into the femoral artery for continuous blood gas analysis. RESULTS: 21 patients were studied with cerebral microdialysis for a total of 91 monitoring days (range 19 hours to 12 days). Of these, 14 patients were also studied with cerebral and arterial Paratrend sensors. The mean (+/- 95% confidence intervals) arterial and cerebral oxygen levels were 123 +/- 10.9 mmHg and 27.9 +/- 5.71 mmHg respectively. The arterial and cerebral carbon dioxide levels were 34.3 +/- 2.35 mmHg and 45.3 +/- 3.07 mmHg respectively. Episodes of systemic hypoxia and hypotension resulting in falls in cerebral oxygen and rises in cerebral carbon dioxide were rapidly detected by the arterial and cerebral Paratrend sensors. Systemic pyrexia was reflected in the brain with the cerebral Paratrend sensor reading 0.17 degree C (mean) higher than the arterial sensor. Elevations of cerebral glucose were detected, but the overall cerebral glucose was low (mean 1.57 +/- 0.53 mM 10 mm membrane; mean 1.95 +/- 0.68 mM 30 mm membrane) with periods of undetectable glucose in 6 patients. Lactate concentrations (mean 5.08 +/- 0.73 mM 10 mm membrane; mean 8.27 +/- 1.31 mM 30 mm membrane) were higher than glucose concentrations in all patients. The lactate/pyruvate ratio was 32.1 +/- 5.16 for the 10 mm membrane and 30.6 +/- 2.17 for the 30 mm membrane. Glutamate concentrations varied between patients (mean 15.0 +/- 10.5 microM 10 mm membrane; mean 28.8 +/- 17.8 microM 30 mm membrane). CONCLUSION: The combination of microdialysis catheters and Paratrend sensors enabling the monitoring of substrate delivery and brain metabolism, and the detection of secondary metabolic insults has the potential to assist in the management of head-injured patients.

Accidents, Traffic↗

PubMed2000

Assessment of quantitative computed tomographic cerebral perfusion imaging with H2(15)O positron emission tomography.

Assessment of quantitative cerebral blood flow on a conventional fast CT machine without the use of specialized equipment may be valuable in the investigation of acute stroke and head injury. We aimed to compare a single slice CT perfusion sequence with H2(15)O positron emission tomography using the sagittal sinus as an input function, a method that avoids unnecessary orbital irradiation. Eight patients were studied, two patients with gliomas, and six with arteriovenous malformations. The dynamic CT perfusion sequence was performed by acquiring the same 10 mm slice 10 times over 30 sec during a 50 ml bolus of intravenous contrast medium given at a rate of 7.5 ml sec-1 using a power injector. The CT perfusion studies were completed without complication. Co-registration was sub-optimal in one patient. Overall the correlation between the two methodologies was encouraging with an average r2 value of 0.524 for individual analyses. When two patients with high flow arteriovenous malformations were excluded the average r2 value increased to 0.640. The results of this CT perfusion methodology are encouraging. Having shown its feasibility, further studies in conditions with lower rates of cerebral blood flow are warranted.

Adult↗

PubMed2000

Expression of the immediate early genes c-Fos and c-Jun after head injury in man.

Immediate early genes (IEC) are expressed in a variety of experimental paradigms including cerebral ischemia and trauma. There is a paucity of information on whether the results of laboratory experiments can be extrapolated from animals into man. To examine this further we hypothesized that expression of c-Fos and c-Jun occurs after contusional head injury in man. We also sought to identify whether there was an association between the level of immediate early gene expression and 1. the outcome one year after head injury, 2. the timing of surgery after head injury. IEG expression was examined using in situ hybridization and immunocytochemistry in brain tissue therapeutically removed in 14 patients with head injury 6 h to 6 days after contusional injury. IEG expression was also examined in tissue removed during elective non-traumatic neurosurgery for comparative purposes. Expression of c-fos and c-jun mRNA was observed in 50% and 64% of head-injured patients respectively. Protein immunoreactivity for these IEGs was evident in 67% of head injured patients. The expression of c-Fos and c-Jun was associated with final outcome. Patients with poorer outcomes had higher levels of gene expression (p = 0.08 for c-Fos and p = 0.006 for c-Jun). No correlation between the timing of surgery and the intensity of gene expression was evident in the trauma patients (r2 = 0.09 and 0.10 for c-Fos and c-Jun respectively). In the non-trauma patients 36% expressed c-fos and 73% expressed c-jun mRNA, with all patients studied expressing c-Fos and c-Jun proteins. We conclude that differential expression of c-Fos and c-Jun occurs in the patients with cerebral contusions. The difference in expression rates between mRNA and protein emphasises the need for analysis of gene products when investigating gene expression. These results support the hypothesis that IEGs may be involved in the pathogenetic mechanisms of contusional head injury. Observations of IEG expression in human brain injury are important in steering animal experimental programmes towards studies that may yield information directly applicable to human brain injury.

Adolescent↗

PubMed2000

A clinical audit of the Hakim programmable valve in patients with complex hydrocephalus.

The objective of the investigation was to determine the pattern of use of the Hakim (Medos) programmable valve implanted in patients with complex hydrocephalus and their clinical outcome. A prospective audit of patients with complex hydrocephalus undergoing Hakim programmable valve implantation between 1989 and 1994 in the United Kingdom and Ireland, was followed-up for a minimum of 5 years. Surgical practice and complications were audited together with clinical outcome. One-hundred-and-thirty-nine patients (80 male, 59 female; mean age 43.4 years; median 47 years; range 1 month-84 years) with complex hydrocephalus due to a wide range of aetiologies were implanted with the Hakim programmable valve. Eighty-eight (63%) had large or massive ventricles prior to implantation; seven (5%) were slit. Fifty-five (40%) had previously been shunted with a fixed pressure system. One-hundred-and-thirty-one (94%) of the Hakim programmable shunts were ventriculoperitoneal; four (3%) ventriculoatrial; two (1.4%) cystoperitoneal; and two (1.5%) lumboperitoneal. The initial opening pressure selected ranged from 50 to 200 mmH2O (median 120). Valves were reprogrammed on average 1.7 times with 143 reprogrammings in the first year after implantation; 67 in the second; 19 in the third; three in the fourth; two in the fifth. Forty-nine (36%) valves were never reprogrammed after implantation. During the 5 years audit period, there were 70 (50%) shunt revisions, 40 of which were performed within 1 year of implantation. Thirty-six (27%) shunts were removed. There were 24 (18%) shunt infections. Subdural collections were identified in 37(27%) patients after Hakim programmable valve implantation; 10 (27%) required surgical drainage. Five (3.7%) patients developed symptomatic slit ventricles after Hakim programmable valve implantation. Headache was improved following reprogramming in 27(71%) of the 38 patients with refractory headache. After Hakim programmable valve implantation, patients underwent an average of 4.6 CT scans (range 1-25); 0.3 MRI (range 1-5) and 1.8 skull radiographs (range 1-20). The mean hospital stay per patient over 5 years was 26 days (range 1-110 days). Five years after implantation, the Glasgow Outcome scale was favourable in 64% of patients. The Hakim programmable valve is useful in the management of patients with complex hydrocephalus and may reduce the need for shunt revision for headache. Non-haemorrhagic, post-shunting, subdural collections identified on routine postoperative CT may be treated by reprogramming.

Adolescent↗