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Background: The necessity of red blood cell (RBC) transfusions in neurosurgical procedures is under debate. Although detailed recommendations exist for many other surgical disciplines, there are very limited data on the probability of transfusions during neurosurgical procedures., Methods: Three-thousand and twenty-six consecutive adult patients undergoing neurosurgical procedures at Saarland University Hospital from December 2006 to June 2008 were retrospectively analyzed for administration of RBCs. The patients were grouped into 11 main diagnostic categories for analysis. The transfusion probability and cross-match to transfusion ratio (C/T ratio) were calculated., Results: Overall, the transfusion probability for neurosurgical procedures was 1.7 % (52/3,026). The probability was 6.5 % for acute subdural hematoma (7/108), 6.2 % for spinal tumors (5/80), 4.6 % for intracerebral hemorrhage (ICH, 4/98), 2.8 % for abscess (3/108), 2.4 % for traumatic brain injury (4/162), 2.3 % for cerebral ischemia (1/44), 1.9 % for subarachnoid hemorrhage (SAH) /aneurysms (4/206), 1.4 % for brain tumors (10/718), 0.8 % for hydrocephalus (2/196), 0.4 % for degenerative diseases of the spine (5/1290), including 3.6 % (3/82) for posterior lumbar interbody fusion (PLIF) and 0 % for epidural hematoma (0/15). The transfusion probabilities for clipping and coiling of SAH were 2.9 % (2/68) and 1.7 % (2/120) respectively., Conclusions: The probability of blood transfusion during neurosurgical procedures is well below the 10 % level which is generally defined as the limit for preoperative appropriation of RBCs. Patients with spinal tumors, acute subdural hematomas or ICH, i.e., patients undergoing large decompressive procedures of bone or soft tissue, had a higher probability of transfusion.

A novel adaptive and approximate shift-invariant wavelet packet feature extraction scheme for event-related potentials (ERPs) in the electroencephalogram (EEG) is introduced in this paper. In this algorithm, the shift-invariant wavelet packed decomposition is done by integrating a cost function for decimation decision in each sub-band expansion. Additionally, a shape adaptation of the wavelet is implemented to find the best adapted wavelet shape for a given class of ERPs. This scheme is used to analyze the time course of the impact of single-pulse transcranial magnetic stimulation (TMS) to the auditory ERPs. We show that the proposed scheme is able to extract even slightest impacts of TMS, making it a promising tool for the extraction of weak ERPs components, particularly in hybrid TMS-EEG/ERP setups.

Unlabelled: A review of the data published on the epidemiology of traumatic brain injuries (TBI) reveals that the data of almost all studies are drawn from local or regional series. Nationwide data are rarely available, or are extrapolated from regional data. In Germany, there has been a nationwide mortality register with ICD-9-coded diagnoses since 1968. In addition, it has been compulsory since 1994 that all hospitals in Germany provide ICD-9 data on all admissions and discharges. Based on data provided by the Federal Bureau of Statistics (Statistisches Bundesamt) in Wiesbaden, all head injuries between 1972 and 1998 were analyzed according to ICD-9 and after 1998 according to the updated ICD-10. The data of hospitalized cases and fatal cases were correlated with population data to calculate incidences and mortality rates. Age-group specific data were also available and analyzed. Head injuries in Germany accounted in 1998 for 19.59% of all injuries. The incidence is 337/100,000. The incidence rate of serious head injury is 33.5/100,000. Mortality decreased continuously from 27.2/100,000 in 1972 to 9.0/100,000 in 2000. The mortality is highest in the group older than 75 years. 68.4% of persons with head injury die before admission to a hospital. After the reunification in 1989/1990, the number of fatal head injuries showed a temporary increase. The number of patients treated in-hospital remained essentially unchanged (276/564 patients in 1998). The majority of hospitalized patients suffered minor head injury., Conclusion: Analysis of the admission/discharge data of all German hospitals reveals surprising inside views of age group-related incidence and mortality rates of head injuries in this country. Future research should be focused on patients with minor head injuries who account for nearly 200,000 cases of in-hospital treatment.

Background: Whether the phase relationship (phase shift) between cerebral blood flow velocity as assessed by transcranial Doppler ultrasound and blood pressure at 0.1 Hz can be used to assess cerebral autoregulation (CA) in patients with severe traumatic brain injury (TBI)., Methods: In 33 healthy volunteers (mean age, SD; 37+/-17 years, range 17-65) middle cerebral artery (MCA) blood velocity (V) was recorded simultaneously with finger blood pressure (BP) over a period of 10 minutes under normocapnic and hypocapnic conditions to generate normative data. In 27 patients with severe TBI (Glasgow Coma scale score < or =8) serial close in time investigations of cranial computed tomography (CT) scanning and phase shift assessment were performed on days 1, 3, 5, and 8 after trauma. Phase shift in the MCA was compared to brain parenchyma lesion size in the MCA territory on CT scanning. Lesion size was classified into 0, normal; 1, presence of a small lesion (diameter <3 cm); 2, presence of a large lesion (>3 cm)., Findings: Compared to normocapnia, hypocapnia significantly increased phase shift at 0.1 Hz from 78+/-28 degrees to 101+/-25 degrees (p < 0.001). In the TBI patients, 115 comparisons between CT findings and CA results were possible. Phase shift detected a pathological CA in 31 instances, which were more frequent in CT lesion type 2 (19/42) than in group 0 (7/44) and group 1 (5/29)., Interpretation: When CA is intended to be assessed by use of phase shift, the hyperventilation setting needs its own reference values. In MCA territories containing a traumatic lesion greater than 3 cm in diameter phase shift at 0.1 Hz will detect a high frequency (44%) of a disturbed state of CA.

Background: In injured brain tissue with a disrupted blood-brain barrier (BBB) catecholamines such as norepinephrine (NE) are known to enhance glucose consumption and cerebral blood flow but may lead to an energy depletion increasing the risk of ischemia. Therefore it is of great interest whether the exogenous administration of NE used mainly to maintain an adequate cerebral perfusion pressure influences CSF NE levels or not, and whether elevated plasma or CSF levels of NE can influence the actual clinical condition. We addressed this issue by measuring the levels of NE in CSF and plasma and correlating them with the actual clinical condition of the patients., Methods: In 29 patients with severe TBI (< 8 points on the Glasgow Coma Scale, GCS) NE levels were analysed by high performance liquid chromatography (HPLC) in paired blood and CSF specimens which were collected from days 1 to 14 after severe TBI (total number of pairs = 121). The integrity of the BBB was evaluated by determining the CSF/serum albumin ratio. The clinical condition of the patients was assessed by GCS., Results: Elevated plasma and CSF NE levels were observed in 50% of all samples, most consistently in patients treated with NE. NE elevation in CSF was independent of whether or not the BBB remained intact. There was no correlation between GCS and the levls of NE in CSF or plasma either in samples from the treated or the untreated group., Interpretation: Exogenous administration of NE seems to increase NE levels in plasma and CSF. However, in this group of patients with severe TBI there was no clinical evidence that exogenous administration of NE was detrimental to the traumatized patients.

Object: Function-preserving neurosurgery requires methods to identify functionally important CNS-areas intraoperatively. We investigated whether a combination of focal cerebro-cortical cooling and monitoring of somatosensory evoked potentials (SEP) is suited for this task, i.e. whether it is able to outline structures belonging to the somatosensory pathway., Methods: In 17 Wistar rats the somatosensory cortex was focally cooled by 20 degrees C below the initial tissue temperature for periods of five minutes. A cryoprobe with a tip diameter of 3 mm was used and tissue temperatures were measured below and at different distances to the cryoprobe. Tibial nerve evoked SEPs and EEG-spectra were recorded continuously., Results: During cortical cooling the SEP-responses showed a marked delay and amplitude increase of the cortically generated components P13 and N18 and a small latency increase of the subcortically generated wave III. EEG-spectra were depressed mainly in the low frequency range. All cooling effects were reversible and in light- as well as electron-microscopic examinations no tissue damage was found., Conclusions: Focal cooling of the cortex induces easily recognizable and reversible changes of the bio-electrical activity without causing any histological damage. Therefore the method seems suitable for identifying eloquent areas. It can be expected that clinical application of the cooling technique in combination with intraoperative electrophysiological monitoring will be helpful to further lower the risk of neurosurgical operations. We propose that cooling mainly interferes with the synaptic transmission within the somatosensory cortex, because the observed amplitude increase can be explained by cold-induced depression of inhibitory cortical activity (disinhibition).

In fifteen cases of brain stem lesions caused by basal tumours, operations, injuries, arteriosclerosis or multiple sclerosis, a paradoxical activity of jaw closing muscles during jaw opening was observed. This inverse activity was the cause of severe trismus in 8 cases. It is the manifestation of a faulty programming of jaw movements in the trigeminal motor area in brain stem. This distinct new brain stem syndrome can only be detected by EMG investigation. EMG findings, pathological background, outcome and treatment possibilities are discussed in this paper.

Stainless steel staples commonly used for skin suture were tested for their suitability as electrodes for recording electrophysiological data. Investigations were performed in vivo and as well as in vitro, and showed the typical behaviour of electrodes made from a polarizable metal, i.e., an increase of electrode impedance with low frequencies. In spite of this fact most electrophysiological data can be recorded if the input impedance of the amplifier is in the common range of 100 MOhms. Advantage of these electrodes is their quick and easy application, their resistance to mechanical stress and the possibility of leaving them in place for a long time.