Detta examensarbete är ett produktutvecklingsprojekt som behandlar utvecklingen av ett koncept av en ny stereotaktisk huvudram för användning inom neurokirurgin. Arbetet har utförts i samarbete med Elekta Instrument AB som är ett av världens ledande företag för utveckling av utrustning som behandlar cancer och andra sjukdomar i hjärnan. Elekta har idag en produkt som heter Leksell Stereotactic System (LSS) och består av en ram och en båge, tillverkade i aluminium, som används vid stereotaktisk kirurgi. I och med att diagnosmetoderna förändras och att främst MRI använder kraftfullare magnetfält finns ett behov av att använda icke elektriskt ledande eller magnetiska material i ramen. Målet med arbetet var att ta fram en ny huvudfixeringsram som fram-för allt var förbättrad inom följande; material, kompatibilitet, design och patientkomfort. Arbetet inleddes med en förstudie och en studie av användarnas antropometriska mått. En QFD genomfördes för att ta fram kundönskemål och krav på produkten. Ett funktions-medel-träd skapades för att studera produktens funktioner. De medel som skapats i funktions-medel-trädet användes sedan för att generera konceptlösningar som sedan utvärderades och en slutlig lösning valdes. Ett materialseminarium hölls där bästa materialet ansågs vara glasfiber förstärkt epoxy tillverkad i RTM med en lackad yta. En del brister fanns med det valda konceptet och som ett resultat skapades ett nytt koncept som i slutändan ansågs bättre och valdes för fortsatt utveckling. Konceptet Doublebend’s, se figur 1, fördelar var dess form, som tillät ingrepp till alla delar av hjärnan, vinklingsbara skruvinsatser och bra möjligheter till tillverkning. Ramens deformation analyserades och resultatet användes vid placering av låsningspunkter på ramen till angränsande adaptrar. En MRI-adapter togs fram och en prototyp tillverkades i SLS. Prototypen användes för validering vid ett möte med en neurokirurg. Slutsatserna från arbetet är att det framtagna konceptet har potential att utvecklas till en bra produkt, men att mycket arbete kvarstår. Djupare analyser, materialprov och detaljkonstruktion återstår som framtida arbete. / This report presents the development of a concept for a new stereotactic head frame for use in neurosurgery. The work has been performed at Elekta Instrument AB, which is one of the world's leading companies for the development of equipment that is used to treat cancer and other diseases of the brain.  Doublebend  The conclusions of the work are that the developed concept has the potential to progress into a quality product, however much work remains. Further analysis, material testing and detailed design remain as future work.

Severe Traumatic Brain Injury (sTBI) is a major cause of mortality and morbidity. At the Department of Neurosurgery Umeå University Hospital subjects with sTBI are treated with an intracranial pressure (ICP) guided therapy based on physiological principles, aiming to optimise the microcirculation of the brain so avoiding secondary brain injuries. The investigations in this thesis are unique in the sense that all patients with sTBI were treated according to the guidelines of an ICP targeted therapy based on the “Lund concept”. As the treatment is based on normalisation of the ICP, the accuracy and reliability of the measuring device is of outmost importance. Therefore the accuracy, drift, and complications related to the measuring device was prospectively studied (n=128). The drift was 0,9 ± 0,2 mmHg during a mean of 7,2 ± 0,4 days and the accuracy high. No clinical significant complications were noted. In 1997 uni- or bilateral decompressive hemi-craniectomy (DC) was introduced into the treatment guidelines. The effect of DC on the ICP and outcome was retrospectively analysed for subjects with sTBI treated 1998-2001. In the subjects who underwent DC the ICP was 36,4 mmHg immediately before and 12,6 mmHg immediately after the DC. The ICP then levelled out at just above 20 mmHg. The ICP was significant lower during the 72 hours following DC. The outcome did not differ between subjects who had undergone DC or not. Subclinical electroencephalographic seizures and status epilepticus have been reported to be common in subjects treated for traumatic brain injury (TBI). This can negatively influence the outcome giving rise to secondary brain injuries. The occurrence of seizures in subjects treated for TBI using continuous EEG monitoring was therefore prospectively studied. During 7334 hours of EEG recording in 47 patients no electroencephalographic seizures were observed. Theoretically, and based on animal studies, prostacyclin (PGI2) can improve the microcirculation of the brain, decreasing the risk for secondary ischaemic brain injury. PGI2 was introduced to the treatment in a prospective randomised double blinded study (epoprostenol 0,5 ng/kg/min). The effect of PGI1 pkt was analysed using the lactate/pyruvate ratio (L/P) measured by cerebral microdialysis in order to study the energy metabolism in the brain. The outcome was measured as Glasgow Outcome Scale (GOS) at 3 months follow-up. Forty-eight subjects were included. The L/P was pathological high during the first day, thereafter decreasing. There was no significant difference in L/P or outcome between the treated and non-treated group. At 3 months the mortality was 12,5% (95,8% was discharged alive from the ICU), and favourable outcome (GOS 4-5) was 52%. In the same study the brain injury biomarkers S-100B and NSE were followed twice a day for five days to evaluate brain injury and investigate the possible use of these biomarkers for outcome prediction. Initially the biomarkers were elevated to pathological levels which decreased over time. The biomarkers were significant elevated in subjects with Glasgow Coma Scale 3 (GCS) and GOS 1 compared with subjects with GCS 4-8 and GOS 2–5, respectively. A correlation to outcome was found but this correlation could not be used to predict clinical outcome. It is concluded that the ICP measurements are valid and the treatment protocol is a safe and solid protocol, yielding among the best reported results in the world, in regard to favourable outcome as well as in regard to mortality. Epoprostenol in the given dose was not shown to have any effects on the microdialysis parameters nor the clinical outcome. In sTBI L/P and brain injury biomarkers can not be used to predict the final outcome.

Patients admitted in similar clinical condition after spontaneous SAH can develop very different clinical courses. This could depend on the severity of the initial global ischemic brain injury at ictus. In the present study, we explored relations between clinical and radiological parameters at admission that indicate a more severe initial impact, and the following days hormone levels and brain metabolism. Early global cerebral oedema (GCE) on computed tomography occurred in 57 % of SAH patients and was associated with a more severe clinical condition. The brain’s glucose metabolism, measured with intracerebral microdialysis (MD), changed the first days. MD-glucose was initially high and MD-pyruvate low. MD-glucose gradually decreased and MD-pyruvate and MD-lactate increased, suggesting a transition to a hyperglycolytic state. This was more pronounced in patients with GCE. Similar patterns were seen for interstitial non-transmitter amino acids. From initial low concentrations, they gradually increased in parallel with MD-pyruvate. The amino acid concentrations were higher for patients admitted in better clinical condition. Insulin lowered MD-glucose and MD-pyruvate even when plasma glucose values remained high. P-ACTH and S-cortisol were elevated early after SAH. GCE was associated with higher S-cortisol acutely. Urine cortisol excretion, indicating levels of free cortisol, were higher in patients in a better clinical condition. Suppressed P-ACTH occurred in periods of brain ischemia. We suggest that GCE on the first CT scan is a warning sign indicating increased vulnerability if the patient is exposed to compromised energy supply or increased energy demand. Reduction of blood glucose after SAH should be done with caution. The temporal change of the glucose metabolism and the amino acid concentrations probably reflect activated repair mechanisms. This should be considered in the intensive care treatment of SAH patients. Finally, our results support earlier observations that the response of the hypothalamic-pituitary-adrenal system is important in critical care.