S Hansen

University of Glasgow, Glasgow, Scotland, United Kingdom

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Publications (60)312.66 Total impact

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    ABSTRACT: Rett syndrome (RS) is a unique X-linked dominant neurodevelopmental disorder affecting 1 in 10,000 females. Mutations in the MECP2 gene located on Xq28 have been identified. Many of the characteristic features evolve due to immaturity of the brain in RS. Cardiorespiratory function should be investigated early to characterise the clinical phenotype of the person with RS because each of the three cardiorespiratory phenotypes; apneustic, feeble and forceful breathers have unique and different management strategies. We report a case of a feeble breather showing a correlation between cortical function and tissue pO(2) and pCO(2). We conclude that subtle changes in the levels of blood gases significantly affect cortical function in RS.
    Brain & development 05/2012; · 1.74 Impact Factor
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    ABSTRACT: Rett syndrome (RTT) is a severe neurodevelopmental disorder affecting almost exclusively females. The Hanefeld variant, or early-onset seizure variant, has been associated with mutations in CDKL5 gene. In recent years more than 60 patients with mutations in the CDKL5 gene have been described in the literature, but the cardiorespiratory phenotype has not been reported. Our aim is to describe clinical and autonomic features of these girls. 10 girls with CDKL5 mutations and a diagnosis of Hanefeld variant have been evaluated on axiological and clinical aspects. In all subjects an evaluation of the autonomic system was performed using the Neuroscope. Common features were gaze avoidance, repetitive head movements and hand stereotypies. The autonomic evaluation disclosed eight cases with the Forceful breather cardiorespiratory phenotype and two cases with the Apneustic breather phenotype. The clinical picture remains within the RTT spectrum but some symptoms are more pronounced in addition to the very early onset of seizures. The cardiorespiratory phenotype was dominated by Forceful breathers, while Feeble breathers were not found, differently from the general Rett population, suggesting a specific behavioral and cardiorespiratory phenotype of the RTT the Hanefeld variant.
    Neuropediatrics 02/2012; 43(1):37-43. · 1.19 Impact Factor
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    ABSTRACT: Purpose : To investigate the function of the peripheral and central nervous system in farmers regularly using organophosphate (OP) compounds either after acute intoxication or following low level repeated exposure. Design : Case control and cross-sectional studies. Materials and Methods : Two groups, each of sixteen farmers regularly involved in dipping sheep, were compared with a group of sixteen healthy controls of similar age range using clinical neurological and neurophysiological assessment. Farmers in group 1 had long-term ill health following episodes of mild to moderate acute OP poisoning while farmers in group 2 had none of the above. Clinical symptoms and signs of neuropathy were recorded. Motor and sensory nerve conduction, electromyography (EMG), quantitative sensory testing and visual, brainstem auditory and somatosensory evoked potentials were measured. Results : A similar pattern of significant abnormalities of distal sensory and motor peripheral nerve axonal dysfunction was found in both farmer groups, but more pronounced in the symptomatic farmers. Conclusions : The findings suggest that long-term peripheral neuropathy can follow acute OP intoxication (group 1). Furthermore, chronic effects may follow repetitive low level exposure to OP compounds (group 2). The profile of dysfunction was similar in the two groups. The parameters measured in the study are useful endpoints in future epidemiological studies.
    07/2009; 11(1):9-22.
  • The Lancet 07/2008; 371(9629):1981-3. · 39.21 Impact Factor
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    ABSTRACT: In Ethiopia, a large percentage of leprosy patients present with established nerve damage. Present techniques for measuring nerve function impairment show no abnormality until 30% of nerve axons are destroyed. Nerve damage in leprosy occurs first in small diameter unmyelinated fibres, then in small myelinated fibres, and much later in large myelinated fibres. The Thermal Threshold Tester (TTT) was used to measure function in nerves carrying heat sensation (unmyelinated C fibres) and cold sensation (thinly myelinated Adelta fibres). A school and community health survey, assessed 234 students and adults aged 10-75 years from Chencha Woreda, an area with low endemicity of leprosy. A group of students in Addis Ababa, exposed to leprosy, were also studied. The upper limits of normal were: wrist hot threshold (HT): 0.17 degrees C, wrist cold threshold (CT): 0.19 degrees C, foot HT: 0.17 degrees C and foot CT: 0.20 degrees C. Both the leprosy group and also controls in Addis Ababa showed significantly increased TTT values. The TTT detects nerve damage before clinical neuritis occurs and is a valuable tool for early diagnosis of leprosy or detecting clinical relapse of treated patients and for sequential and quantitative monitoring of small diameter nerve function in other neuropathies.
    Ethiopian medical journal 11/2007; 45 Suppl 1:25-33.
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    ABSTRACT: In Ethiopia, where leprosy has been one of the commonest causes of peripheral nerve enlargement and dysfunction, nerve functions are assessed by a battery of "physical" tests. Voluntary Muscle Test (VMT) and Graded Sensory Skin Test (STG) are standard tests used for persons with leprosy. Normal values for nerve function tests (NFT) in Highland Ethiopians have not previously been determined, but have been taken from standard textbooks. In this study, normal values for NFT were determined by VMT, STG, 2-Point Discrimination Tests both static and moving, and Thermal Threshold Test. Physiological enlargement of right ulnar and radial-cutaneous nerves has been recognised by some leprologists, but we were unable to find written records in the available medical literature. We assessed 236 students and adults aged 10-75 years from Chencha Woreda, an area with low endemicity of leprosy for 25-30 years. Two affected by leprosy were excluded from the analysis. NFT thresholds were affected variously by age, exercise and skin factors, domicile and exposure to organo-phosphates. Nerve size was affected by age, gender, exercise, skin fold thickness, body mass index. Exercise related physiological nerve enlargement has been documented. These data provide a usefull baseline for investigation of peripheral nerve function in highland Ethiopians.
    Ethiopian medical journal 11/2007; 45 Suppl 1:61-72.
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    ABSTRACT: Eight peri-menopausal women, five with borderline lepromatous leprosy and three with borderline tuberculoid leprosy, self-referred complaining of 'burning of the face. Four were seen in 1993, three having been treated as 'menopausal'without betterment and four were seen in 1997. Eight peri-menopausal women who self-referred because of facial burning', and seven women who self-referred for other problems had a careful review of clinical records and were assessed fully for leprosy including graded sensory skin testing of the face, and standard nerve function tests. On examination three in each group of four complaining of facial burning were found to have major loss of facial sensation and one had generalised neuritis without significant facial involvement. Treatment with antileprotics and steroids resulted in recovery of facial sensation, although one later became blind. Of the seven who self-referred without facial burning, five had no facial sensory loss and two had slight loss of facial sensation.
    Ethiopian medical journal 11/2007; 45 Suppl 1:35-41.
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    ABSTRACT: In conjunction with an investigation of nerve function tests of highland Ethiopians in an area of low endemicity of leprosy for 25-30 years, a comprehensive health survey was performed. We assessed 236 subjects, 118 females and 118 males, 177 students and 59 adults (Others) aged 10-75 years from Chencha woreda. We used a detailed medical, personal and social history, anthropomorphic measurements and complete physical examination. We identified six areas of medical concern: Intestinal parasite and diarrhoeal diseases affected 62%, despite treatment of all students and symptomatic adults the recurrence rate was high; skin diseases/conditions affected 88%; eye injections affected 26%; dental decay affected 33%; 20% had hypertension 14% requiring treatment; 11% gave a personal and/or family history of tuberculosis, 44% gave a history of BCG immunisation, while 34% had BCG scars, the lowest percentage (11%) being in students from Daramallo woreda. Supplies of clean water, effective disposal of human excreta and control of flies would greatly reduce intestinal, skin and eye infections. Regular tooth cleaning and possibly fluoridation of drinking water should improve dental health, with diet and exercise for young hypertensives. BCG immunisation in Chencha and Daramallo woredas (inaccessible areas) needs urgent attention.
    Ethiopian medical journal 11/2007; 45 Suppl 1:43-60.
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    ABSTRACT: In the pre-sulphone and early sulphone years children of leprous parents had been followed in a few prospective studies to observe the development of leprosy. No studies were made of the growth and development of these children. A prospective, open-ended, cohort study began in 1975 with follow-up of both mothers and their children until 2003. 156 pregnancies were studied consisting of 36 non-leprous (NL), 25 tuberculoid and borderline tuberculoid leprosy (TT&BT) (released-from-treatment), 18 with TT&BT (active), 42 borderline lepromatous leprosy (BL) and 35 lepromatous leprosy (LL). Babies of mothers with leprosy had lower birth weight, smaller placentae, grew more slowly, had more infections and higher infant mortality than those of non-leprous mothers. The findings were most marked in babies of LL mothers. Growth in childhood was uneventful, infants of LL mothers catching up by age 3.6 years. Childhood infections were common in all groups but more serious for children of lepromatous mothers. The puberty skeletal growth spurt, and, for the girls, menarche was delayed for children studied compared with a new healthy control group, with catch-up by late teens. These findings were most marked in children of lepromatous, especially LL, mothers. Impaired growth in utero and infancy is probably due to immunological factors but we could find no explanation for the delayed growth in adolescent children of LL mothers.
    Ethiopian medical journal 10/2007; 45 Suppl 1:9-23.
  • M. Staber, S. Hansen, P O. O. Julu
    European Journal of Anaesthesiology - EUR J ANAESTH. 01/2007; 24.
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    ABSTRACT: We have used a novel neurophysiological technique in the NeuroScope system in combination with conventional electroencephalography (EEG) to monitor both brainstem and cortical activity simultaneously in real-time in a girl with Rett syndrome. The presenting clinical features in our patient were severe sleep disturbances, irregular breathing in the awake state dominated by Valsalva's type of breathing followed by tachypnoea and very frequent attacks of seizures and vacant spells. Our novel neurophysiological data showed that the patient was a Forceful Breather according to the breathing categories in Rett syndrome. She had frequent abnormal spontaneous brainstem activation (ASBA) preceded by severe attacks of hypocapnoea, which was caused by a combination of Valsalva's type of breathing and tachypnoea and all these together were responsible for the seizures and non-epileptic vacant spells. The ASBA was not detectable in conventional EEG and there were no epileptiform changes in the EEG during the seizures and vacant spells caused by the hypocapnic attacks, therefore these were pseudo-seizures. The record of brainstem activity confirmed that these were autonomic events, a kind of "brainstem epilepsy". We successfully treated the sleep disturbance with Pipamperone, a 5-hydroxytryptophan antagonist of receptor type 2 and we prevented the severe hypocapnoea during Valsalva's type of breathing and during tachypnoea using carbogen (a mixture of 5% carbon dioxide and 95% oxygen), which we gave by inhalation. Our treatment drastically reduced the autonomic events, promoted whole night sleep and significantly improved the quality of life in our patient. She can now participate in normal family activity which was previously impossible before treatment.
    Brain and Development 12/2006; 28(10):625-32. · 1.67 Impact Factor
  • S Hansen, M Staber
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    ABSTRACT: We have investigated the accuracy of the Colin tonometry module, a non-invasive alternative to intra-arterial blood pressure (BP) measurement. The claims of previous publications range between good agreement to significant discrepancies between the Colin tonometry and intra-arterial methods. The Colin method relies on calibration of the tonometry module using an oscillometric method. Our aim was to look at the effect of this calibration on the accuracy. Ten conscious patients who already had an indwelling arterial catheter were studied. The Colin monitor was set to perform ten calibration cycles first with the oscillometric cuff on the same arm as the tonometry module and secondly on the opposite arm. Simultaneous recording of BP wave forms from the intra-arterial BP transducer and the Colin monitor allowed comparison of beat-by-beat systolic, diastolic and mean BP. There was considerable inter- and intra-patient variation. In the worst case, the error range was 41 mmHg over ten calibrations. Analysis of variance showed that contra- and ipsilateral calibrations gave a significantly different bias while the multiple calibrations accounted for a significant proportion of the variability in systolic BP error. The Colin Tonometry method is not accurate enough to be used with confidence in clinical practice. The main reason for this is its reliance on an oscillometric method for calibration of the tonometry module. Single BP measurements, using either manual or semiautomatic instruments may vary considerably from the 'true' BP due to short-term perturbations of BP.
    European Journal of Anaesthesiology 10/2006; 23(9):781-7. · 2.79 Impact Factor
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    ABSTRACT: In dogs with spontaneous heart disease, an electronically generated measurement of cardiac vagal tone, the cardiac index of parasympathetic activity, was a sensitive, simple and inexpensive measure of the severity of heart failure. Dogs with cardiac disease and an index score less than 3 were at 15.8 (95 per cent confidence interval 2.9 to 87.2) times the risk of dying within a year than those with a score of 3 and over. The measurement of the index provided an objective and reliable beat-by-beat measurement of cardiac vagal tone, which was prognostically useful in dogs with heart disease.
    The Veterinary record 02/2005; 156(4):101-5. · 1.80 Impact Factor
  • M. Staber, S. Hansen
    European Journal of Anaesthesiology - EUR J ANAESTH. 01/2005; 22.
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    ABSTRACT: We investigated whether there was mental effort in response to verbal commands in a 16-year old girl with autism, a high degree of non-compliance with commands and symptoms of autonomic dysfunction by monitoring the brainstem autonomic tone during an attempt to perform isometric exercise. An index of cardiac vagal tone (CVT), cardiac sensitivity to baroreflex (CSB), heart rate (HR) and mean arterial blood pressure (MAP) were measured simultaneously. Physical non-compliance with our commands meant there was no force applied by the patient during the attempted exercise, but CVT and CSB were both reduced and sustained at very low levels throughout the attempt, while MAP and HR were increased concurrently to higher levels in the same period. This vagal withdrawal to allow concurrent increases in HR and MAP is an arousal response appropriate for isometric exercise, which is a sign of a positive mental effort to comply with our commands. These results demonstrate discordant mental and physical efforts in our patient. In this particular case, the physical inabilities in some instances could have been mislabelled as mental non-compliance due to autism. It would be worthwhile to investigate the prevalence of discordant mental and physical efforts in autism.
    Brain and Development 01/2005; 26(8):519-24. · 1.67 Impact Factor
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    ABSTRACT: To study cardiovascular control in the period leading to vasovagal syncope we monitored beat-to-beat blood pressure, heart rate (HR) and forearm blood flow in 14 patients with posturally related syncope, from supine through to tilt-induced pre-syncope. Signals of arterial blood pressure (BP) from a Finapres photoplethysmograph and an electrocardiograph (ECG) were fed into a NeuroScope system for continuous analysis. Non-invasive indices of cardiac vagal tone (CVT) and cardiac sensitivity to baroreflex (CSB) were derived on a beat-to-beat basis from these data. Brachial vascular resistance (VR) was assessed intermittently from brachial blood flow velocity (Doppler ultrasound) divided by mean arterial pressure (MAP). Patients underwent a progressive orthostatic stress test, which continued to pre-syncope and consisted of 20 min head-up tilt (HUT) at 60 deg, 10 min combined HUT and lower body suction (LBNP) at -20 mmHg followed by LBNP at -40 mmHg. Pre-syncope was defined as a fall in BP to below 80 mmHg systolic accompanied by symptoms. Baseline supine values were: MAP (means +/- S.E.M.) 84.9 +/- 3.2 mmHg; HR, 63.9 +/- 3.2 beats min-1; CVT, 10.8 +/- 2.6 (arbitrary units) and CSB, 8.2 +/- 1.6 ms mmHg-1. HUT alone provoked pre-syncope in 30 % of the patients whilst the remaining 70 % required LBNP. The cardiovascular responses leading to pre-syncope can be described in four phases. Phase 1, full compensation: where VR increased by 70.9 +/- 0.9 %, MAP was 89.2 +/- 3.8 mmHg and HR was 74.8 +/- 3.2 beats min-1 but CVT decreased to 3.5 +/- 0.5 units and CSB to 2.7 +/- 0.4 ms mmHg-1. Phase 2, tachycardia: a progressive increase in heart rate peaking at 104.2 +/- 5.1 beats min-1. Phase 3, instability: characterised by oscillations in BP and also often in HR; CVT and CSB also decreased to their lowest levels. Phase 4, pre-syncope: characterised by sudden decreases in arterial blood pressure and heart rate associated with intensification of the symptoms of pre-syncope. This study has given a clearer picture of the cardiovascular events leading up to pre-syncope. However, the mechanisms behind what causes a fully compensated system suddenly to become unstable remain unknown.
    The Journal of Physiology 06/2003; 549(Pt 1):299-311. · 4.38 Impact Factor
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    ABSTRACT: A large number of published studies support the notion that long term, low level (LTLL) exposure to organophosphorus (OP) esters may cause neurological and neurobehavioral effects. In order to differentiate these from other effects of OP such as the acute cholinergic episodes, intermediate syndrome and organophosphate induced delayed neuropathy (OPIDN), the term Chronic Organophosphate Induced Neuropsychiatric Disorder (COPIND) will be used purely for the ease of reference. The question addressed in this particular review is whether LTLL exposure to OP may produce neurotoxicity. The profile and the degree of overlap of the various components of COPIND have been addressed elsewhere and description of the possible mechanisms for COPIND is outside the scope of this article. COPIND can be classified under two headings; those produced following one or more acute clinical cholinergic episodes, and those produced without such preceding attacks. With regards to the first group, there are a total of 11 studies, all of which support the existence of a positive link between exposure to OP and neurotoxicity; six of these studies comprise descriptions of large numbers of cases without controls while five additional studies employ controls. Appearance of neurotoxicity does not seem to be related to the number or the intensity of acute cholinergic attacks. With regards to the second group, three types of studies can be identified. Firstly, there are five studies using experimental animals, all of which showed a positive link between OP and neurotoxicity. Secondly, a total of seven case studies without controls, some involving large numbers of patients, concluded that there is a positive link between OP and neurotoxicity. Thirdly, 19 studies investigated such a link using cases and control groups. Of these, 15 studies (about 80%) showed a positive link and only four failed to identify any link between OP and neurotoxicity. Annotation of all the 19 studies according to ideal set of criteria showed that only a few of these comply with the rules of excellence and all of these few showed a positive link. Furthermore, the only study carried out blind without the identification of subjects or controls, showed a positive link between OP and neurotoxicity. This blind study estimated the overall incidence of a form of neurotoxicity in people exposed to OP to be about 40 times higher than in the general population. The type of neurological involvement was unique and different from OP induced syndromes previously described. The profile of the neurological involvement was similar to that in COPIND whether or not preceded by acute cholinergic episodes, thus providing further evidence that these two neuropathies probably share a similar mechanism. There is a characteristic pattern of involvement of 15 functional indices of the autonomic nervous system examined in our laboratory. There are, in addition, preferential anatomical sites of target organs affected, selective preservation of cholinergic function within the same neuropathy-positive site, and evidence of mal-function of cardiac chemoreceptors in patients exposed to OP. The peripheral nerve involvement in OP exposure is predominantly sensory in nature affecting both small and large fibre populations. Neurobehavioral involvement of mainly cognitive dysfunction and other features are also described in other studies. The weight of current evidence is therefore very much in favor of the motion that chronic low-level exposure to OP produces neurotoxicity. Criticisms levelled against this motion are unfounded and probably misconceived.
    Toxicology 01/2003; 181-182:23-33. · 4.02 Impact Factor
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    ABSTRACT: To classify clinical diseases of the subjects with abnormal indices of peripheral neuropathy identified in field studies of sheep farmers and dippers exposed to organophosphate pesticides. To explore what neuropsychological profiles, if any, may be associated with neurophysiological damage in these subjects. A case-control study (79 subjects) nested within the cross sectional study (685 subjects) of sheep farmers from the field study. Three groups with no, possible, and probable or definite neuropathy according to field studies were recruited. Investigations comprised symptoms of neuropathy, neurologial signs, motor and sensory nerve conduction, electromyography, quantitative sensory testing, and neuropsychological tests. The incidence of clinical neuropathy increased from 7% in the no neuropathy group to 52% in the probable or definite neuropathy group based on nerve conduction measurements or presence of neurological signs. Sensory abnormalities were found more often than motor deficits. Small diameter nerve fibres were also affected more than large fibres. The neuropathy is predominantly sensory and is characteristic of distal, chronic neuropathy with no acute features. Small fibre populations are affected more than large fibre populations. Increasing severity of neuropathy was associated with anxiety and depression as measured in the neuropsychological tests.
    Occupational and Environmental Medicine 08/2002; 59(7):434-41. · 3.22 Impact Factor
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    ABSTRACT: To investigate the reproducibility of measured indices of chronic peripheral neuropathy from a field study of sheep dippers when compared with similar measurements carried out in a clinical setting. A stratified random sample of field study subjects was invited to attend a clinic. Neuropathy was measured both in the field and at the clinic with a modified version of a standard symptoms questionnaire and quantitative sensory thresholds for hot, cold, and vibration. These were combined into a classification of the likelihood of neuropathy with a neuropathy scoring system. Indicators of sensory abnormality were based on comparison of sensory thresholds to age dependent reference values derived from an external reference group. Only 51% of subjects were assigned similar classifications in the field and clinic based on the neuropathy scoring system. Of the component indices, grouped symptom scores, with 65% of subjects showing exact agreement, proved to be more reproducible than quantitative sensory test indicators. There were biases in the comparison of field and clinic measurements of hot and vibration sensations, but no evidence of greater variation between individual people in sensory thresholds in the field relative to at the clinic. The neuropathy scoring system proved to be of limited reproducibility, due in a large part to the lack of reproducibility of the indicators of sensory test abnormality caused by inadequate temperature control. However, the symptoms score and measured sensory thresholds could be used separately as indices of neuropathy in exposure-response analyses.
    Occupational and Environmental Medicine 08/2002; 59(7):442-6. · 3.22 Impact Factor
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    ABSTRACT: To investigate the hypothesis that chronic low level exposure to organophosphates (OPs) in sheep dips is related to clinically detectable measures of polyneuropathy. The design was a cross sectional exposure-response study of sheep dippers and other non-exposed groups. The study group consisted of 612 sheep dipping farmers, 53 farmers with no sheep dipping experience, and 107 ceramics workers. Retrospective exposure information was obtained by questionnaire based on stable and easily identifiable features of sheep dipping found during the first phase of the study; in particular, estimates of handling concentrate and splashing with dilute dip. Neurological assessments were based on a standard neuropathy symptoms questionnaire, and thermal and vibration quantitative sensory tests. Adjusted for confounders there was a weak positive association between cumulative exposure to OPs and neurological symptoms, the significance of which was dependent on the inclusion of a few individual workers with extremely high exposure. There was no evidence of an association between cumulative exposure and the thermal or vibration sensory thresholds. However, separating the effects of exposure intensity and duration showed a higher prevalence of symptoms, primarily of a sensory type, among sheep dippers who handled the OP concentrate. There was also evidence that sensory and vibration thresholds were higher among concentrate handlers, the highest exposed group of dippers. The findings showed a strong association between exposure to OP concentrate and neurological symptoms, but a less consistent association with sensory thresholds. There was only weak evidence of a chronic effect of low dose cumulative exposure to OPs. It is suggested that long term health effects may occur in at least some sheep dippers exposed to OPs over a working life, although the mechanisms are unclear.
    Occupational and Environmental Medicine 12/2001; 58(11):702-10. · 3.22 Impact Factor

Publication Stats

1k Citations
312.66 Total Impact Points

Institutions

  • 1985–2012
    • University of Glasgow
      • Clinical Physics Section
      Glasgow, Scotland, United Kingdom
  • 2005
    • Rutgers New Jersey Medical School
      Newark, New Jersey, United States
  • 2002
    • Imperial College London
      Londinium, England, United Kingdom