Search

Following craniotomy, the decision to resect a brain tumour is based on (1) the surgeon's interpretation of preoperative imaging, such as MRI, (2) correlating the imaging to the surgical field, (3) visual inspection of the surgical field, and (4) palpation thus providing biomechanical information on tumour and brain. There is a degree of subjectivity in the use of palpation for biomechanical evaluation. Ultrasound elastography is a technique for determining more objective biomechanical information at depth in the form of relative strain, thus indirectly stiffness, within an ultrasound scan plane. In addition, neuro-navigation techniques assist in correlating preoperative imaging to the surgical field. We present two cases where ultrasound elastography with co-registered MRI, using neuro-navigation, was used intra-operatively during brain tumour resection. Correlation with the co-registered MRI was excellent in both patients. Strain contrast between brain and tumour was evident in elastograms produced in both patients; the tumour had a lower strain, hence was stiffer compared with brain. When strain applied was increased slip between tumour and brain was detected. All these findings corresponded with the surgical findings. Ultrasound elastography with co-registered MRI is a promising imaging technique, which can be used intra-operatively to provide biomechanical information prior to resection.

Objectives. Our objectives were to examine the assumption that the natural history of congenital lumbosacral lipomas in children presenting early and those presenting late is the same, and to determine whether there are factors that might predict the post-operative outcome of surgery among the presenting features of children with lumbosacral lipomas. Methods. The authors present a clinical series of 50 consecutive cases of congenital lumbosacral lipoma that had been treated surgically. All patients underwent both pre- and post-operative urological assessment and pre-operative imaging with MRI. The case notes, urology assessments and MRI films were studied to provide data on the clinical presentation, follow-up history and urological outcome of the children, as well as on the anatomical features of their lipomas. Results. Analysis of the data revealed a predominance in girls and a bimodal distribution of age at presentation with peaks at 0–2 and 7–8 years. Skin stigmata were more frequent in children below 6 years of age than in older children (P=0.035). The MRI scans demonstrated that the conus lay within the sacral canal more often in girls than boys (P=0.025). Severe bladder dysfunction was significantly more frequent in those presenting at =3 years of age (P=0.017) and there were more normal outcomes in patients operated upon before the age of 3 than in those operated upon at or after this age (P

The objective was to assess the efficacy of dural tenting sutures as a prophylactic measure against extradural haemorrhage following craniotomy. A comparison was made of postoperative extradural haemorrhage between a surgeon always using tenting sutures and a surgeon who never uses them. The subjects consisted of 130 adult patients, 44 with postoperative scans, with normal blood coagulation who underwent elective supratentorial craniotomy (September 1998 to December 2000). Outcome measures were haematoma volume and midline shift as measured on CT and reoperation due to extradural haematoma. The group using tenting sutures had larger median extradural haematoma (2.5 vs 2.0 ml) and midline shift (3 vs 0 mm) than the omitting group. These differences were not significant (P = 0.74 and 0.84). Reoperation due to extradural haemorrhage occurred in 3.6% of the group using tenting sutures and in 0% of the group omitting them. Prophylactic dural tenting sutures do not reduce the size of extradural haematomas in this study. A prospective, randomized trial is needed to eliminate surgeon bias.

A comparison study is presented, which examines the outcome, complications and cost of stereotactic brain biopsy performed with a frameless versus a frame-based method. The technique of frameless stereotactic biopsy has been shown previously, in both laboratory and in vivo studies, to achieve a level of accuracy at least equal to frame-based biopsy. The investigators have validated the technique in a large clinical series. The frameless and frame-based series were concurrent, comprising 76 and 79 cases, respectively. The frameless stereotactic technique involved standard needle biopsy, targeted by an image-guidance system and directed by a novel rigid adjustable instrument-holder. Frame-based biopsies were performed with the CRW and Leksell systems. There were no significant differences in the demographics, lesion site, size and pathologies between the groups. Operating theatre occupancy and anaesthetic time were both significantly shorter for the frameless series than the frame-based series (p < 0.0001). In addition, the complication rate in the frameless biopsy series was significantly lower than in the frame-based series (p = 0.018). This resulted in lower ITU bed occupancy (p = 0.02), shorter mean hospital stay (p = 0.0013) and significant cost savings (p = 0.0022) for the frameless stereotactic biopsy group, despite the greater use of more expensive MRI in these cases. This comparison study demonstrates that the superior imaging, target visualization and flexibility of the technique of frameless stereotactic biopsy translates into tangible advantages for safety, time and cost when compared with the current gold-standard of frame-based biopsy. The principles are discussed and the authors propose a definition for the term 'frameless stereotaxy'.

Objective and importance Trigeminal neuralgia is a rare feature of basilar invagination, which is itself a complication of osteochondrodysplastic disorders. Microvascular decompression is an unattractive option in medically refractory cases. The conventional percutaneous approach to the trigeminal ganglion is anatomically impossible because the foramen ovale points inferiorly and posteromedially. We report a new technique for image-guided trigeminal injection in a patient with basilar invagination complicating osteogenesis imperfecta. Clinical presentation A 26-year-old woman with osteogenesis imperfecta presented with a 3-year history of typical left maxillary division trigeminal neuralgia, which was poorly controlled by carbamazepine at the maximum tolerated dose. She had obvious cranial deformities, left optic atrophy, delayed left eye closure, tongue atrophy, but normal facial sensation and corneal reflexes. A computed tomographic scan and magnetic resonance imaging confirmed severe basilar invagination. Technique Frameless stereotactic glycerol injection of the left trigeminal ganglion was performed under general anesthesia using the infrared-based EasyGuide Neuro system (Philips Medical Systems, Best, The Netherlands) with magnetic resonance imaging and computed tomographic registration. The displaced and distorted left foramen ovale was cannulated via a true frameless stereotactic method with the trajectory determined by virtual pointer elongation. The needle placement was confirmed with injection of contrast medium into the trigeminal cistern. The path needed to enter the foramen traversed the right cheek, soft palate, and left tonsil. The patient went home pain-free with a preserved corneal reflex and no complications. Conclusion Frameless stereotaxy allows customization to individual patient anatomy and may be adapted to a variety of percutaneous procedures used in areas where the anatomy is complex.

✓ The authors present the results of accuracy measurements, obtained in both laboratory phantom studies and an in vivo assessment, for a technique of frameless stereotaxy. An instrument holder was developed to facilitate stereotactic guidance and enable introduction of frameless methods to traditional frame-based procedures. The accuracy of frameless stereotaxy was assessed for images acquired using 0.5-tesla or 1.5-tesla magnetic resonance (MR) imaging or 2-mm axial, 3-mm axial, or 3-mm helical computerized tomography (CT) scanning. A clinical series is reported in which biopsy samples were obtained using a frameless stereotactic procedure, and the accuracy of these procedures was assessed using postoperative MR images and image fusion.The overall mean error of phantom frameless stereotaxy was found to be 1.3 mm (standard deviation [SD] 0.6 mm). The mean error for CT-directed frameless stereotaxy was 1.1 mm (SD 0.5 mm) and that for MR image—directed procedures was 1.4 mm (SD 0.7 mm). The CT-guided frameless stereotaxy was significantly more accurate than MR image—directed stereotaxy (p = 0.0001). In addition, 2-mm axial CT-guided stereotaxy was significantly more accurate than 3-mm axial CT-guided stereotaxy (p = 0.025). In the clinical series of 21 frameless stereotactically obtained biopsies, all specimens yielded the appropriate diagnosis and no complications ensued. Early postoperative MR images were obtained in 16 of these cases and displacement of the biopsy site from the intraoperative target was determined by fusion of pre- and postoperative image data sets. The mean in vivo linear error of frameless stereotactic biopsy sampling was 2.3 mm (SD 1.9 mm). The mean in vivo Euclidean error was 4.8 mm (SD 2 mm). The implications of these accuracy measurements and of error in stereotaxy are discussed.

Technical advances and pioneering surgeons have established neuroendoscopy as an accepted diagnostic and therapeutic tool. The clinical indications for endoscopy, variety of operative techniques and number of endoscopic surgeons continue to increase steadily. However, there are fundamental limits to the scope of freehand endoscopy principally governed by the need for direct vision of anatomical and pathological structures. In addition, whilst the expert neuroendoscopist is only occasionally disorientated by complex distorted anatomy, the rising number of novices are likely to be mislead relatively often. We report the integration of neuroendoscopy with an optical neuronavigation system to provide interactive image-guided neuroendoscopy. This combination both removes the constraining requirement for direct vision and provides accurate localisation to guide the surgeon during surgery. We describe the clinical application of this method to two cases where image-guided endoscopy was essential to the safe completion of the procedure.

We report the first case of an Ectopic adrenocorticotrophin (ACTH)-secreting pituitary adenoma (EAPA) located within the posterior nasal septum associated with Nelson's syndrome, which eluded diagnosis for over a decade. In this report, we explore the reasons for such diagnostic difficulty and suggest ways in which an earlier diagnosis may be made.A 19 years old Lebanese man presented in 2000, with overt Cushing's syndrome confirmed with markedly elevated urine free cortisols and failed dexamethasone suppression tests. An unsuppressed ACTH and a possible 5 mm adenoma on MRI (Magnetic Resonance Imaging) pituitary suggested Cushing's disease. The patient underwent trans-sphenoidal surgery (TSS), but histology revealed normal pituitary tissue and Cushing's syndrome persisted. A repeat MRI pituitary showed no anomaly, and extensive investigations failed to locate an ectopic lesion. Subsequently a bilateral adrenalectomy was performed. Over the ensuing years, the patient developed Nelson's syndrome with hyperpigmentation and markedly elevated ACTH levels. Repeated high dose dexamethasone suppression tests, corticotrophin releasing hormone (CRH) tests, and CRH stimulated inferior petrosal sinus samplings (IPSS) suggested a pituitary origin of the ACTH. Two further TSS were unsuccessful. The pituitary was irradiated. Subsequent review of his previous MRIs revealed an enlarging mass within the posterior nasal septum, which was excised in 2011. The histology confirmed the diagnosis of an EAPA within the nasal septum.Ectopic ACTH-secreting pituitary adenomas can occur not only along the developmental route of Rathke's pouch, but other aberrant locations giving a clinical and biochemical picture identical to Cushing's disease or Nelson's syndrome. Clinicians should suspect an EAPA, when a central ACTH source seems to be apparent with no obvious pituitary adenoma. A detailed MRI involving possible EAPA sites aids in locating these unusual lesions.

A 41-year-old man presented with a sudden onset severe occipital headache, vomiting, neck stiffness and photophobia. He had been previously well, aside from chronic mid and lower back pain. There was no focal neurological deficit and a plain CT head scan was normal. Subsequent lumbar puncture (LP) was heavily bloodstained with analysis showing sequential increase in red blood cell count (144 000×106/L first tube and 225 000×106/L third tube). It was not possible to undertake testing for xanthochromia as the cerebrospinal fluid (CSF) supernatant was grossly haemolysed. We prescribed nimodipine for presumed intracranial subarachnoid haemorrhage. CT angiogram and a digital subtraction cerebral angiogram showed no intracranial vascular abnormality. His symptoms improved and we made a putative diagnosis of benign thunderclap headache. At this point, we attributed the bloodstained CSF to traumatic LP and he was discharged with analgesia and neurology follow-up. Three weeks later he developed a 1-week history of new lumbar back pain, numbness of the sacrum and penis, shooting pains in the lower limbs, progressive constipation, involuntary flatus and urinary urgency. On readmission, he had lower limb weakness, brisk knee and ankle jerks and flexor plantar responses. He had a sensory level to pin prick at T12. His bladder was palpable with a postmicturition residual volume of 750 ml. T2 weighted MRI spine showed oedema within the lower cord extending to the conus. There were multiple aberrant flow voids within the spinal canal, …

Identification of the anatomical location and mechanical properties such as adherence at the tissue tumour interface may be of clinical benefit in determination of tumour resectability and prognosis. There are currently no imaging modalities in routine clinical practice that can provide this information. This paper presents the development of a new imaging technique based on ultrasound elastography, called slip elastography, for determination of the anatomical location and measurement of the adherence between two surfaces. The theoretical basis of slip and its definition in relation to shear are described. In vitro testing with gelatine phantoms to determine the optimal parameters for shear strain estimation and slip boundary measurement and to test reliability are also described. The results suggest that slip elastography can reliably identify the anatomical location of a slip boundary and can measure the externally applied axial force required to initiate slip at that boundary in vitro. The vector based shear strain estimator was the most robust and worked with minimal angular dependence with minimal non-slip shearing artefact.

The Oxford Handbook of Neurology is a practical and concise, quick reference guide for use on the ward and in clinical settings. It includes a wealth of information and invaluable clinical guidance passed down by generations of neurologists, but not often available in textbooks.

Recurrent laryngeal nerve (RLN) palsy is a recognised complication of anterior cervical discectomy (ACD) surgery. We report our experience of intra-operative neuromonitoring using RLN stimulation in 19 patients undergoing ACD surgery. This simple and safe technique has the potential to reduce the incidence of RLN palsy in this patient group.

This study furthers previous work by this group [1] on the use of ultrasound elastography intra-operatively in the brain. Real-time 2-dimensional (2D) ultrasound elastograms were acquired during neurosurgical operations for brain and spinal cord tumors, and, in select cases, approximately real-time 3-dimensional (3D) elastograms (volumes of axial strain data) were acquired in the brain. For the first time, elastograms were successfully generated in the spinal cord using vascular pulsations to generate internal strains. The results revealed strain data that correlated well with the surgeon's assessment of the stiffness of the tissues, and areas of reduction in cross-correlation coefficient and very high axial strain at tumor boundaries were found to correspond to cleavage planes. Off-line axial normal strain and axial shear strain calculation assisted in image interpretation. Benefits of this method in neurosurgery include pre-informing the surgeon as to the stiffness of the lesion and identification of dissection planes, both of which can lead to safer surgery.

A young man presented with neck pain following a fall. Neurological examination was normal. Computed tomography (CT) scanning showed a normal brain and an undisplaced fracture of the C5 lamina and wedge fracture of the T1 vertebra. He was managed conservatively at another hospital by cervical immobilisation with a halo device. Two months later he had two generalised seizures. Systemic and neurological …

The concurrent presence of multiple primary brain tumours with different histological characteristics is very rare. A case of dual intracranial benign tumours comprising pituitary adenoma and vestibular schwannoma is described. The aetiology and genetic association of these pathologies is explored and the literature of multiple intracranial tumours of different cell types is reviewed.

Spinal cord injury, whether due to trauma, neoplasia or medical conditions, is devastating for the patient, affecting every aspect of physical, social and psychological life. No one who regularly treats such patients can fail to be moved by their struggle to adjust. Since most of the aetiologies are either traumatic or benign, the patient will have a near normal life expectancy if medical complications are avoided. The very existence of Lin's huge textbook testifies to the major advances in spinal cord medicine achieved over the past three decades. This is dramatically illustrated by mortality rates among traumatic paraplegics due to renal complications which stood at 80% for those injured in World War One, fell to 25% during the Korean war and reached very low percentages for the Vietnam conflict. Whereas renal complications formerly prevailed as the cause of death, the main reason for concern in the first six months after injury are now suicide and accidental self-harm. This highlights both the success of medical therapies and the importance of psychological support as an active component of rehabilitation. The manifold physical, medical and psychosocial aspects of spinal cord medicine require the attention of an experienced multidisciplinary team, and in the UK there are several spinal injury units with excellent facilities and experienced dedicated staff. Unfortunately, places are severely restricted and a large proportion of patients with spinal cord injury will never be offered inpatient treatment at such units. For the clinicians struggling to manage spinal cord conditions in a conventional hospital environment Lin's textbook provides an authoritative and contemporary source of knowledge. With seventy-four chapters by 128 authors (most of them from the USA), it proceeds logically from the basic sciences to clinical management including psychosocial issues. The introductory section includes the anatomy and physiology of the spinal cord, imaging and overviews of epidemiology and outcomes. These chapters are necessary for completeness but are rather general and superficial. The second section on acute management of cord injury deals well with the decision-making process and controversies of surgical decompression and stabilization in spinal cord injury, but naturally does not cover the detail of surgical procedures. The third section entitled ‘Medical Management’ addresses the wide range of medical complications that occur with great regularity in spinal cord injury, dealing with each in turn in good detail. This section includes chapters on frequently overlooked complications such as disordered thermoregulation and the immune system response as well as the commonly appreciated problems of respiratory dysfunction and thromboembolism. Section four deals with bladder, bowel and sexual dysfunction and provides comprehensive advice on all aspects of these difficult management issues. Section five, on the neurological aspects of spinal cord care, is a miscellaneous arrangement of items on physiology, investigations, management of spasticity, various myelopathies and autonomic dysfunction. Whilst some of these provide only an overview others offer in-depth insight into aspects of spinal cord injury that are otherwise not dealt with in detail elsewhere. Section six, on musculoskeletal care, provides an excellent set of chapters about this very important aspect of secondary prevention. Section seven, self-evidently vital, addresses rehabilitation from every angle. Section eight deals with recent advances in spinal cord research, providing analyses of progress in neural regeneration, cord repair and retraining among others. Section nine concerns special topics in spinal cord medicine and incorporates further miscellaneous chapters that demonstrate the comprehensive nature of this text. The final section, on psychosocial issues and support environment, is perhaps the most important and instructive part of the book and is done well. The breadth, detail and inclusiveness of this text is impressive. Whichever aspect of spinal cord medicine one is faced with, this text will offer management advice and clinical information. In my practice I regularly see patients with spinal cord injury secondary to trauma, neoplasia and inflammatory processes who have to be managed in the neurosurgical unit. With the advice of these experts readily to hand, I shall feel more confident in managing these patients during their lengthy stays.

We report an adult patient who developed a right-sided hydrocoele following a lumboperitoneal shunt. While hydrocoeles have been described as a rare complication following ventriculo- and lumboperitoneal shunts in children, we are unaware of any previously reported cases of hydrocoeles resulting from such shunts in adults.

OBJECTIVE A lockable guide device, adjustable for positioning, was used to obtain samples for tissue analysis during brain biopsy procedures performed using an interactive image guidance system. Clinical validation of this technique, which was developed for true frameless stereotactic biopsies, and analyses of the histological yield, complication rate, and patient demographic characteristics for a large series of frameless stereotactic biopsies were the purposes of this study. METHODS Demographic, radiological, surgical, and clinical data were prospectively collected for a series of 125 frameless stereotactic biopsies performed using the technique described in detail previously. RESULTS Eighty-six procedures were magnetic resonance imaging-directed and 39 were computed tomography-directed. The mean diameter of the biopsied lesions was 36 mm, and the mean distance from the skin was 35.8 mm. Sixteen percent of the patients harbored multiple lesions, and 5.6% of the biopsied lesions were infratentorial. The mean operative time (including the entire anesthetic time) was 1.5 hours. The smear examination findings were corroborated by conclusive histological results in 96% of the cases, and definitive positive diagnoses were obtained in 122 cases (97.6%). Ten patients experienced surgical complications, but the sustained morbidity rate was 2.4% (including the death of a patient who was in critical clinical condition preoperatively and who died 2 mo later as a result of a chest infection; mortality rate, 0.8%). CONCLUSION This true frameless stereotactic biopsy technique was associated with low morbidity and mortality rates and an excellent diagnostic yield, with overall results at least as good as those observed for frame-based stereotaxy. The excellent accuracy results demonstrated previously and statistically significant reductions in operative time, as well as improved image presentation, target selection, and simplicity, support the use of this frameless stereotactic technique in preference to frame-based biopsy techniques.

In recent years, advances in computer technology and a significant increase in the accuracy of medical imaging have made it possible to develop systems that can assist the clinician in diagnosis, planning, and treatment. This paper deals with an area that is generally referred to as computer-assisted surgery, image-directed surgery, or image-guided surgery. We report the research, development, and clinical validation performed since January 1996 in the European Applications in Surgical Interventions (EASI) project, which is funded by the European Commission in their "4th Framework Telematics Applications for Health" program. The goal of this project is the improvement of the effectiveness and quality of image-guided neurosurgery of the brain and image-guided vascular surgery of abdominal aortic aneurysms, while at the same time reducing patient risks and overall cost. We have developed advanced prototype systems for preoperative surgical planning and intraoperative surgical navigation, and we have extensively clinically validated these systems. The prototype systems and the clinical validation results are described in this paper.

Object. This prospective study was conducted to quantify brain shifts during open cranial surgery, to determine correlations between these shifts and image characteristics, and to assess the impact of postimaging brain distortion on neuronavigation. Methods. During 48 operations, movements of the cortex on opening, the deep tumor margin, and the cortex at completion were measured relative to the preoperative image position with the aid of an image-guidance system. Bone surface offset was used to assess system accuracy and correct for registration errors. Preoperative images were examined for the presence of edema and to determine tumor volume, midline shift, and depth of the lesion below the skin surface. Results were analyzed for all cases together and separately for four tumor groups: 13 meningiomas, 18 gliomas, 11 nonglial intraaxial lesions, and six skull base lesions. For all 48 cases the mean shift of the cortex after dural opening was 4.6 mm, shift of the deep tumor margin was 5.1 mm, and shift of the cortex at completion was 6.7 mm. Each tumor group displayed unique patterns of shift, with significantly greater shift at depth in meningiomas than gliomas (p = 0.007) and significantly less shift in skull base cases than other groups (p = 0.003). Whereas the preoperative image characteristics correlating with shift of the cortex on opening were the presence of edema and depth of the tumor below skin surface, predictors of shift at depth were the presence of edema, the lesion volume, midline shift, and magnitude of shift of the cortex on opening. Conclusions. This study quantified intraoperative brain distortion, determined the different behavior of tumors in four pathological groups, and identified preoperative predictors of shift with which the reliability of neuronavigation may be estimated.

The initial clinical experience with a prototype of the EasyGuide Neuro surgical navigation system is presented together with some measurements of intraoperative brain shift taken with the neuro-navigator. The EasyGuide Neuro is an infrared-based system employing hand-held localisers with light-emitting diodes tracked by a table-mounted camera array. Standard orthogonal reformats which intersect at the pointer tip position are displayed by the workstation in near real-time. We have prospectively studied the 31 consecutive patients undergoing surgery with the neuronavigator during the first 3 months of clinical use. General patient data, system accuracy checks and surgical impact are described. In a subgroup of 16 patients measurements of brain shift were taken at the brain surface, at the deepest point of surgery and at the bone surface offset. The latter was used to correct for registration errors. We found a significantly greater shift of the cortical surface than of deep structures (p < 0.02) with this method. These measurements are presented as evidence supporting the validity of navigational guidance in clinical practice.

It is uncertain whether the use of image-guided surgery has an influence on operating time. We prospectively studied the time requirements which have to be invested for using image-guided surgery and performed a comparison of operating room times from 125 matched pairs of image-guided and conventional operations. Our study revealed that neuronavigation has to be regarded as time neutral in general neurosurgery, whereas in stereotactic surgery, namely biopsy retrival, a significant reduction of anaesthetic time can be achieved through the complete separation of imaging and operation in the frameless approach.

(2003). Diffuse idiopathic skeletal hyperostosis resulting in dysphagia and aspiration pneumonia. British Journal of Neurosurgery: Vol. 17, No. 5, pp. 467-468.

To address the question of managing subarachnoid haemorrhage (SAH) in the older patient, the management and outcome of 199 consecutive patients agedor = 60 years with a confirmed diagnosis of subarachnoid haemorrhage (n = 186) or an unruptured intracranial aneurysm (n = 13) were reviewed. In seven patients, the cause of the SAH was an arterio-venous malformation and these were excluded from further analysis. Angiography was performed in 141 patients with a complication rate of 2.1%. Angiography was not performed in 51 patients and, in this cohort, the in-patient mortality rate was 68.6% and only 27.5% had a favourable outcome at discharge. Operation was not performed in 21 patients with demonstrated aneurysms for a variety of reasons. In this group, the in-patient mortality rate was 47.6% and 38.1% had a favourable outcome at discharge. Eighty-one patients in good neurological grade underwent surgery for a ruptured aneurysm and six patients underwent surgery for a symptomatic unruptured aneurysm. The surgical mortality was 1.1% and a favourable outcome at discharge was achieved in 83.9% of patients. Thirty-three patients were angiographic negative and there was a favourable outcome in 97% of this group. The management mortality in these selected patients admitted to the Department of Clinical Neurosciences was 24.4% and a favourable outcome was recorded in 66.2% of patients. Long-term follow-up (median 40 months, range 3-120 months) was obtained in 97% of discharged patients. The probability of survival at 60 months for patients in good condition at discharge was 0.826 (95% confidence interval 0.722-0.894).(ABSTRACT TRUNCATED AT 250 WORDS)

(1986). Overhead Allocations and ‘Optimal’ Pricing Rules of Thumb in Oligopolistic Markets. Accounting and Business Research: Vol. 16, No. 64, pp. 309-317.

This paper sheds some empirical light on the relationship between disbursements of aid to British industry and the characteristics of the receiving industries. The technique of canonical correlation is used to test the hypothesis that the provision of government aid to British industry forms a coherent set of industrial policies. The results for 1975/6 support the hypothesis suggesting that aid disbursements bear a systematic relation to those industrial characteristics which reflect the general objectives of government policymakers. However, the pattern of assistance is complex with each of the three identifiable components of aid; building and works, plant and machinery, and research and development, having a significant and separate set of relations with the industrial characteristics.

This paper examines the nature of the objective function of the firm when operating under conditions of uncertainty. Robustness is presented as a purposeful maximand for decision making both under conditions of certainty and uncertainty - a robust decision being one in which the decision maker retains the maximum flexibility with regard to future decisions after an initial decision has been made. Its incorporation within a managerial objective function provides a measurable scale for making choices between alternative courses of action, including under conditions of internal organizational conflict and environmental reaction by other decision makers.

THE empirical analysis of market performance within industrial economics is still predominantly focused on market structure-performance relations. When applied to cross-section industrial studies, this approach implicitly assumes that industries are insignificantly dispersed from their respective short-run equilibrium positions and that each industry (or market) is homogeneous in terms of the behaviour of buyers and sellers. However, these assumptions will not be appropriate in the case of markets experiencing market share instability to the extent that the relative positions of competitors are changing. Structural adjustments towards new equilibrium positions resulting from competitors having different degrees of market success suggests that corporate market behaviour has an effect on market performance independent of any market structure variable. Recently, there has been a small, but growing, recognition of the importance of the behavioural mechanism in determining corporate market performance which is reflected in the work of Hatten and Schendel [6], Dorward [3], [4] and Caves and Porter [1]. These studies suggest that corporate behaviour has an independent effect on short-run market performance. Such an effect is particularly likely in the case of product differentiated industries where the market performance of competing manufacturers is affected by their relative success in matching planned product characteristics to buyer preferences. The importance of heterogeneous buyer preferences in explaining the variation of such variables as market share and profitability between firms means that detailed buyer requirements must be analysed in addition to the different competitive strategies of manufacturers. Thus, rather than assuming the complete structural dependence of the behavioural mechanism, empirical research needs to investigate the role of buyer and seller behaviour in affecting market performance. This paper focuses on the relationship between the purchasing behaviour of truck operators and the changing market performances of UK medium and heavy truck manufacturers between 1976-79. While this is a relatively short period for the analysis of structural change, there have been substantial changes in fortune for some of the leading manufikturers. In the 7.5-20 tonne gross vehicle weight (gvw) sector, Bedford, the market leader, had a decline in market share from 39.7 to 29.7 percent and in the over 20 tonne s'ector Leyland, the market leader, saw its share fall from 27 to