Intervertebral disc replacement for cervical degenerative disease--clinical results and functional outcome at two years in patients implanted with the Bryan cervical disc prosthesis.

BACKGROUND: This is a prospective study of patients with degenerative cervical disease who underwent ventral discectomy and disc replacement with the Bryan((R)) cervical disc prosthesis. The objective was to investigate clinical outcome at 2 years of patients implanted with the Bryan disc and to evaluate function of the implant itself. METHODS: Fifty-four consecutive patients with cervical disc herniation and/or spondylosis with preserved mobility in the affected spinal segments were enrolled. Patients presented clinically with cervical radiculopathy and/or myelopathy with or without neck pain. A standard anterior cervical discectomy was carried out and a Bryan disc was implanted in the affected levels. A total of 59 prosthetic discs were implanted, in 49 patients at a single level and in 5 at two adjacent levels. The neurological status was evaluated pre-operatively and at one and two years thereafter. Plain X-rays, CT, and MRI were used for pre-operative diagnostics. Post-operative follow-up was done by X-rays. FINDINGS: All patients had an excellent or good neurological outcome according to the Odom criteria. Loss of function (motion range <3 degrees) was found in 7 (12%) out of 59 Bryan discs at two years after surgery. Heterotopic ossification (HO) of the McAffee grades 1-4 was seen in a total of 17 (29%) segments. There were no implant dislocations or migrations. CONCLUSIONS: Implantation of the Bryan disc resulted in excellent or good neurological outcome in all patients. The surgical technique was safe and without complications. Twelve percent of the implanted Bryan discs lost mobility at two years, mainly due to HO. A trend was seen towards development of HO in the operated segments. Further investigations with longer follow-up periods and with a control group (e.g. fusion with intervertebral cage) will be necessary for a definitive assessment of the long-term functionality and benefits of artificial cervical discs.

Results and outcome of neurosurgical treatment for extradural metastases in the cervical spine.

Metastatic lesions are the most common spinal extradural tumours. Significant advances in their neurosurgical management have been made in the last two decades. This retrospective study was undertaken to summarise the long-term results of surgery and the outcome of patients with cervical spine metastases. Sixty-two patients with cervical spine metastases who underwent instrumented spinal surgery at a single centre in an 12-year period (1989-2000) were analysed. All patients presented with local pain and with either neurological deficits, spinal instability, or a combination of both. A standard anterior approach to the cervical spine was chosen, and a partial or total vertebrectomy and vertebral body replacement with subsequent anterior instrumented fusion were carried out in all cases. General and neurological status was evaluated at baseline and in regular intervals thereafter. Plain X-rays, CT, and MRI were used for preoperative planning. Postoperative follow-up was done by X-rays. The mean follow-up time for all patients was 1.5 years. A stable bony fusion of the cervical spine was achieved in 60 patients (96.8%), with two additional patients needing a further procedure for maintaining the mechanical stability of the spine. There was mild early surgery-related morbidity, and no mortality. The most frequent temporary surgery-related side effect was reversible vocal cord paresis in 5 cases (8.0%). There were 3 cases (4.8%) of early instrumentation failure. One of these was symptomatic and underwent second-look surgery. No late complications occurred due to instrumentation hardware failure. The 1-year survival rate of all patients after surgery was 58%, and the 2-year survival rate was 21%. Our results demonstrate that surgical removal of extradural metastases with subsequent instrumented fusion is a low-morbidity and low-complications procedure with high rates of permanent stabilisation of the compromised cervical spine. In addition, it improves the neurological deficits and relieves the local pain in a significant proportion of patients. Excellent local control of malignant disease can be achieved by the surgical procedure aided by subsequent local and systemic adjuvant therapy. Overall survival time and prognosis of the patients, however, are mainly depending on the type and the stage of the primary malignancy.

Long-term intrathecal infusion of drug combinations for chronic back and leg pain.

Continuous intrathecal infusion of analgesic drugs by implantable pumps is recognized as an established treatment option for patients with chronic pain resistant to oral or parenteral medication. Polyanalgesia, the simultaneous use of more than one intrathecal analgesic drug, is practiced relatively often, but there are only a few published clinical studies on intrathecal polyanalgesia for chronic nonmalignant pain. This pilot study represents a long-term evaluation of a treatment regimen consisting of intrathecal morphine admixed with bupivacaine, clonidine, or midazolam in patients with chronic nonmalignant back and leg pain due to degenerative lumbar spinal disease. Twenty-six adult patients have been treated by intrathecal programmable pump-controlled infusion of analgesic drugs and followed for up to 3.5 years (27 +/- 11 months). Combination of morphine with a second drug was used in 10 cases, morphine with 2 additional drugs in 12 cases, and morphine with 3 additional drugs in 4 cases. Mean daily doses at 24 months after pump implantation were 6.2 +/- 2.8 mg for morphine, 2.5 +/- 1.5 mg for bupivacaine, 0.06 +/- 0.03 mg for clonidine, and 0.8 +/- 0.4 mg for midazolam. Nineteen patients reported excellent or good long-term treatment results, 6 patients had sufficient results, and only 1 patient complained of poor therapeutic efficacy. No long-term clinical side effects of intrathecal polyanalgesia were noted. Mean morphine dose had to be increased from 1.2 mg at baseline to 5.1 mg at 24 months due to tolerance development and disease progression. This experience suggests that intrathecal polyanalgesia employing morphine combined with additional nonopioid drugs can have a favorable analgesic efficacy in patients with complex chronic pain of spinal origin, and lacks major drug-related complications.

Secondary tumor formation after stereotactic biopsy for intracerebral metastatic disease.

BACKGROUND: There are only a few published cases of iatrogenic tumor seeding and distant neoplastic growth along the path of the cannula after stereotactic biopsy. CASE DESCRIPTION: We report the case of a female patient with a solitary lung cancer metastasis in the left parietal brain lobe. The tumor was stereotactically biopsied and treated by radiosurgery. One month after the initial biopsy, a smaller de novo tumor mass located along the track of the stereotactic cannula was detected by contrast-enhanced MRI. The spatial location of this neoplastic nodule and the short time before development of a macroscopic lesion seemed to confirm iatrogenic tumor cell spread due to the stereotactic procedure. CONCLUSION: Our findings and the reviewed literature suggest that this complication is rare. Nevertheless, neurosurgeons should be aware of the potential risk and, if necessary, should be able to modify the technical procedure and the adjuvant treatment.

Immune response induced by retrovirus-mediated HSV-tk/GCV pharmacogene therapy in patients with glioblastoma multiforme.

This study was conducted to investigate immunological components of somatic gene therapy for primary glioblastoma multiforme (GBM) in adults. It involved 13 patients treated by surgical resection of tumor with subsequent radiation therapy. Seven of them received additional herpes simplex virus thymidine kinase/ganciclovir (HSV-tk/GCV) gene therapy by direct intracerebral injection of retrovirus (RV) vector producing cells (VPC) during tumor surgery and subsequent systemic administration of GCV. Peripheral blood for FACS immunophenotyping, isolation of peripheral mononuclear cells (PMNC), and serum ELISA assays for IL-12 and soluble Fas ligand (sFasL) was collected daily during the first 4 post-operative weeks. Tumor specimens were obtained at primary or recurrent surgery and at autopsy. Tumors from gene therapy patients showed varying degrees of peritumoral necrosis around the former tumor resection cavity. Numbers of tumor-infiltrating lymphocytes found weeks after gene therapy were not significantly increased compared with primary tumors. Mitotic tumor cells were sparse close to the VPC injection sites, but abundant in brain areas somewhat distant from these sites. Serum ELISA revealed significantly increased sFasL and IL-12 levels in the gene therapy group compared with controls. Immunophenotyping of PMNC did not show a significant activation of T cells or NK cells during gene therapy. Interferon gamma secretion was evaluated by ELISPOT assays employing PMNC cocultivated with autologous tumor cells. It demonstrated an antitumor immune response in the gene therapy group, but not in the control group. These findings support the concept of in vivo induction of a systemic immune response by local intracerebral HSV-tk/GCV pharmacogene therapy for primary human GBM.

Outcome in Cloward anterior fusion for degenerative cervical spinal disease.

The Cloward ventral interbody fusion is often employed for treatment of cervical degenerative disease. The present study was aimed at evaluating results and complications in this classical type of autologous bone graft procedure in a cohort of patients with radiculopathy (RP) or myeloradiculopathy (MRP). Indications for and limitations of the technique were investigated by retrospective data analysis in a series of 106 patients (30 females and 76 males). These underwent single or multiple level Cloward fusion in a total of 145 levels. Neuroradiological investigations included lateral and antero-posterior cervical spine X-rays, axial CT scans, and MRI. The presence of postoperative ossification and stable bony fusion in the fused segments was confirmed by X-rays and, when necessary, by CT. The median postoperative follow-up period was 6.5 years (range 4-10.5 years). Short term outcome in RP patients was good in 26 cases (92.9%) and fair in 2 cases (7.1%). A good short term outcome was seen in 55 MRP patients (70.5%), a fair outcome in 20 patients (25.6%), and a poor outcome in 3 patients (3.8%). Patients having myelopathy signs for less than 1 year had a significantly better outcome than those with clinical signs for more than 1 year (p < 0.05). MRP patients below the age of 40 years had a significantly better outcome than those above the age of 40 (p < 0.05). In the long term, radiculopathy was cured or significantly improved in 92.8% of cases, and myeloradiculopathy in 64%. One year after surgery, there were 139 stably fused segments (96%) and 6 segments showing osseous non-union (4%). Plain lateral radiographs demonstrated, besides the bony fusion in the respective segment, relatively frequent graft collapse with slight to severe correction losses and kyphotic deformity of the cervical spine. However, these findings did not necessarily correlate with the clinical outcome. Autologous bone graft harvesting caused a rather high short-term morbidity with donor site pain and/or wound haematoma in 33% of the cases. These surgery-related complications, however, were of a temporary nature, as long-term complications (cutaneous hypaesthesiae) were found in 2 patients (1.8%) only. In conclusion, Cloward anterior cervical fusion for degenerative spinal disease is a relatively simple and safe surgical procedure with favourable short and long term results. In our hands, graft donor site complications dominate the side effects of surgery, and the percentage of non-unions is rather low. Because of the relatively frequent bone graft collapse and the late loss of postural correction of the spine, we cannot recommend the Cloward type fusion for multisegmental procedures. In such cases, an instrumented plate fusion should be carried out in order to prevent graft collapse and non-union, and to allow for a shorter convalescence period.

Transcranial Doppler sonography in adult hydrocephalic patients.

Transcranial Doppler sonography (TCD) is a noninvasive technique for measurement of cerebral blood flow velocity (CBFV) in the major arteries of the circle of Willis. Dynamic changes in the pulsatility index (PI) and the resistance index (RI), as calculated from TCD data, allow for an assessment of the forces acting on the terminal vasculature of the brain. The present study was designed to investigate a possible relationship between TCD parameters and intracranial pressure (ICP) changes in adult patients with hypertensive hydrocephalus. Blood flow velocity in the middle cerebral artery (MCA) was studied by TCD in 29 hydrocephalus patients and in 20 healthy controls. ICP was measured in the patient group before ventricular shunting and was correlated with TCD data. The mean CBFV in hydrocephalic patients prior to ventriculoperitoneal shunting was significantly lower than in the control group. Compared to normal persons, systolic and end-diastolic CBFV values in patients were significantly decreased, suggesting an increased distal cerebrovascular resistance. PI and RI values in patients with elevated ICP prior to shunting were significantly increased in comparison to those of normal persons. There was a statistically significant positive correlation of preshunting ICP and mean preshunting values of RI (r=0.50, P<0.01) in hydrocephalic patients, but no significant correlation between PI and ICP, and between CBFV and ICP. Immediately after shunting, ICP returned to normal, and PI and RI values decreased significantly, while the mean CBFV increased. In a subgroup of hydrocephalic patients with a preshunting ICP value >35 mm Hg (n=6), the changes described above were more pronounced than in the subgroup with preshunting ICP values <35 mm Hg, which suggests an exponential degree of influence of ICP on TCD parameters. In conclusion, TCD may provide a tool for assessment of ICP in adult patients with occlusive hydrocephalus, although an exact noninvasive measurement of ICP by TCD seems impossible. Changes in the RI and PI indices appear to be useful indicators of elevated ICP.

First Light Measurements of Capella with the Low-Energy Transmission Grating Spectrometer aboard the Chandra X-Ray Observatory.

We present the first X-ray spectrum obtained by the Low-Energy Transmission Grating Spectrometer (LETGS) aboard the Chandra X-Ray Observatory. The spectrum is of Capella and covers a wavelength range of 5-175 Å (2.5-0.07 keV). The measured wavelength resolution, which is in good agreement with ground calibration, is Deltalambda approximately 0.06 Å (FWHM). Although in-flight calibration of the LETGS is in progress, the high spectral resolution and unique wavelength coverage of the LETGS are well demonstrated by the results from Capella, a coronal source rich in spectral emission lines. While the primary purpose of this Letter is to demonstrate the spectroscopic potential of the LETGS, we also briefly present some preliminary astrophysical results. We discuss plasma parameters derived from line ratios in narrow spectral bands, such as the electron density diagnostics of the He-like triplets of carbon, nitrogen, and oxygen, as well as resonance scattering of the strong Fe xvii line at 15.014 Å.

Hardware failures in spinal cord stimulation for failed back surgery syndrome.

Spinal cord stimulation (SCS) is an efficient means for treatment of the postsurgical lumbar spine condition known as failed back surgery syndrome (FBSS). Although the devices and the implantation techniques are well established and the technology is sophisticated, there are some complications caused by hardware failures. This study was aimed at identifying the most frequent types of hardware failures and their causes in FBSS patients treated with SCS. In a retrospective analysis, a group of 42 FBSS patients using single lead SCS for 6-74 months was evaluated. Only hardware failures were considered in the analysis, and parameters such as occurrence of failure after primary implantation of the device, frequency and site of failure, stimulation time to failure (TF), and overall time of SCS usage were recorded. In the patient group studied, 12 surgical corrections of the hardware were carried out in 10 patients. In eight patients there was a single corrective procedure, in two additional cases there were two surgically corrected hardware failures each. The most often encountered type of hardware failure was lead breakage or disruption of insulation (percutaneously placed Quad leads only) leading to short circuiting and dysfunction (n= 8). Second in frequency were receiver (model 3470) failures due to insulation leakage at the plug connection site (n= 2). In one case, extension cable breakage caused dysfunction of the system, and another dysfunction was caused by distal extension cable disconnection. In conclusion, SCS is a low-complication procedure for treatment of benign low-back pain, but seems to be prone to lead and insulation failures.

[Unusual intra-extracranial extension of meningioma of the lateral skull base]. / Ungewöhnliche intra-extrakranielle Ausdehnung eines Meningeoms der lateralen Schädelbasis.

Extracranial meningiomas are rare tumors of the lateral skull base. A 37-year-old woman presented with tinnitus und progressive hearing loss of her right ear. A painful mass lesion was also palpable in her mandibular angle. CT and MRI scans revealed an intracranial mass with extension to the lateral skull base. These findings suggested the occurrence of a paraganglioma or meningioma. In a two-stage surgical procedure tumor was extirpated without functional impairment to the patient. Histology of the excised lesion demonstrated an endotheliomatous meningioma. Since an extracranial meningioma can present as a mass lesion of the lateral skull base, CT and MRI scans are essential in preoperative surgical planning.

Is it useful to measure supratentorial ICP in the presence of a posterior fossa lesion? Absence of transtentorial pressure gradients in an animal model.

Previous studies with animal models of supratentorial ICP elevation have demonstrated a pressure gradient between the supratentorial and the infratentorial compartments. The present study was designed to investigate the possible presence of such a gradient in the case of infratentorial ICP elevation. An inflatable infratentorial balloon catheter was implanted in seven domestic pigs. The infratentorial ICP (ICPi) was measured in the left cerebellar hemisphere, and the supratentorial ICP (ICPs) was measured in the left cerebral hemisphere. The corresponding pulse amplitudes (ICPi-PA, ICPs-PA) were recorded in both compartments, and the cerebral perfusion pressure (CPP) was calculated. ICPi and ICPs values prior to balloon inflation were 4.4 (SD 2.2) and 4.1 (SD 2.3) mm Hg, respectively, and increased to 63.1 (SD 32.6) and 62.3 (SD 28.1) mmHg after balloon inflation. ICPi-PA rose from 3.1 (SD 0.43) to 12.8 (SD 8.0) mmHg, and ICPs-PA rose from 3.2 (SD 0.63) to 13.0 (SD 7.1) mmHg. CPP decreased from 86.1 (SD 12.0) to 55.4 (SD 14.6) mm Hg. The paired difference between ICPi and ICPs values was 0.44 (SD 1.96) mmHg, and the paired difference of ICP amplitudes was 0.03 (SD 1.19) mmHg. All these differences in infratentorial and supratentorial values were statistically not significant. In conclusion, infratentorial ICP elevation in the presented pig model leads to a uniform ICP elevation in the intracranial space without development of a considerable pressure gradient below and above the tentorium. In the low pressure part of the ICP curve, cerebrospinal fluid connects the compartments and contributes to the pressure equilibrium. The early obstruction of the foramen magnum by intruding cerebellar tissue seems to isolate the infratentorial from the spinal compartment. In the high-pressure part of the curve, the upwards cerebellar transtentorial herniation takes over the pressure transfer, and the whole intracranial space can be considered as a single compartment in the pig.

Occipito-cervical fusion with the cervical Cotrel-Dubousset rod system.

Diseases and conditions which cause instability of the craniocervical junction and the adjacent upper cervical spine are relatively common and potentially life-threatening. Direct internal occipitocervical fusion (OCF) is a modern means of surgical treatment in such cases, and has some advantages over simple immobilization of the affected segments. The present study was designed to evaluate surgical handling, results, and complications with a recently developed instrumentation for OCF, the Cotrel-Dubousset rod-and-hook system (CD). Fourteen consecutive patients with occipito-cervical instability due to fractures, degenerative or neoplastic disease or malformations underwent OCF with the CD system. Autologous or allogeneic bone and bone substitutes such as hydroxyapatite were used to augment the CD fusion. Patients were followed clinically and neuroradiologically for 1 to 4 years (mean 20 months). Assessments were routinely performed at 1 week, 1 month, 3 months, 1/2 year, and every year after surgery. There was no immediate surgery-related morbidity or mortality, and no major late complications due to hardware failure. A stable bony fusion according to radiological criteria was achieved in all cases. No implant breaks or loosening and dislocation of the hooks or the screws were encountered. In no case did neurological deterioration occur after surgery. Short-term evaluation at 1 week after surgery showed no difference with respect to neurological symptoms as compared with the pre-operative findings, except for a patient reporting improvement of paraesthesia on the first postoperative day. The long-term effects were, however, beneficial to most patients, as the fusion alleviated neck pain in 13 cases and improved neurological deficits in 3 of the 4 cases with pre-operative motor weakness or paraesthesia. In conclusion, internal OCF with the CD system, an implant which is easy to handle and safe for the patient, is a technique with a high rate of successful bony fusion. Since no halo placement is needed after surgery, patients have considerable gain of quality of life as compared to other standard surgical techniques.

Anterior cervical fusion with the Orion locking plate system.

STUDY DESIGN: This study was conducted to evaluate an anterior cervical fusion plate system, the Orion locking plate, regarding its surgical handling, hardware-related failures, and short-term and long-term results. OBJECTIVES: A comprehensive evaluation of the implant in a broad range of patients with cervical spine diseases. SUMMARY OF BACKGROUND DATA: Locking plates are the most recent devices for achieving anterior cervical spinal fusion and offer considerable advantages such as faster and easier implantation and fewer implant-related failures than older plate systems. METHODS: Ninety-six patients were investigated. All underwent anterior cervical plate fusion as a component of the surgical treatment for symptomatic degenerative cervical spinal disease or for vertebral destruction caused by trauma, tumor, or inflammation. Besides plate fixation, 6 of the 96 patients had a combined ventrodorsal fusion. In 28 cases, one or more vertebral bodies were removed and replaced with titanium place-holders. The remaining 62 patients were first treated by intervertebral inlay placement, and the fused segments were subsequently plated. Neurologic signs and symptoms were evaluated before and after surgery and during a follow-up period of at least 1 year. RESULTS: The rate of neurologic improvement was highest in radiculopathy patients and lowest in patients with severe myelopathy. In all cases, control radiographs demonstrated a solid bony fusion. Clinical deterioration after surgery was seen in four cases of severe myelopathy in which considerable neurologic deficits existed before surgery, possible because of rapid decompression of the cord and associated microvascular alterations. In two of these cases, there was long-term improvement. Additional general complications caused by surgical retraction included temporary swallowing disturbance in seven patients and a large wound hematoma in one. Hardware failures were encountered in three cases, all of them caused by improper implantation technique and not material failure, per se. CONCLUSION: In the study group, the Orion locking plate was easy to use, failure-free if properly implanted, safe for the patient and supported solid bony fusion in every case.

Coronally oriented vertical fracture of the axis body: surgical treatment of a rare condition.

The neurosurgical management in a rare case of vertical axis fracture is presented along with discussion of the supposed pathogenetic mechanisms and the biomechanics underlying this type of cervical spine injury. Comprehensive neuroradiological investigation prior to surgery clearly demonstrated the dislocation of the anterior part of the axis body with concomitant C 2/C 3-disk injury. Therefore, the unstable fracture had to be managed by a one-time combined ventrodorsal approach using anterior C 2-C 3 locking plate fusion and C 2 bilateral dorsal transpedicular screw fixation. No operative morbidity resulted from this procedure, and stable bony fusion was achieved with minimal restriction of head mobility and with minor residual complaints. This case illustrates the variable biomechanical response of the upper cervical spine to trauma and the advantages of a non-standard surgical approach for internal fixation of the injured cervical spine.

Unusual explanation for the death of a car passenger.

After collision of a car with the left rearside against a steel mast the 19-year-old front seat passenger was found comatose on the seat. CT imaging showed a depression fracture parietal on the left with an intracerebral haemorrhage on the opposite side. The cause of the injury was unknown to the surgeons at the time of operation. Despite neurosurgical intervention the patient died 24 h after the accident. The post-mortem showed an additional depression fracture at the base of the skull in the right temporal region arousing suspicion of an impalement injury. Only inspection of the car by the forensic pathologists revealed the gas pressure telescopic shock absorber to be the cause of the head injury.

Prognostic factors in malignant glioma: influence of the overexpression of oncogene and tumor-suppressor gene products on survival.

Despite the use of multimodal therapy, higher-grade glioma is still uniformly fatal in the adult population. There is a considerable difference between the length of survival in each given patient, even within the same tumor type and malignancy grade group, suggesting that there are factors that might differentially influence outcome. To identify such factors, 107 patients with anaplastic or malignant glioma were retrospectively investigated. Clinical parameters and paraclinical data on the p53, mdm2, and EGFR genes at the DNA or protein level were evaluated by univariate analysis and Cox proportional hazards regression modeling. Kaplan-Meier survival estimation demonstrated that immunohistochemical positivity for mdm2 protein in patients with anaplastic astrocytoma or with glioblastoma multiforme was associated with a shorter survival time (p = 0.02). P53 gene mutations and immunopositivity for the epidermal growth factor receptor (EGFR) protein were not significantly related to poor prognosis. The Cox proportional hazards model revealed immunohistochemical positivity for p53, mdm2, or for both of them, the presence of postoperative irradiation, and the extent of surgical resection of tumor to be variables significantly associated with prolonged survival. EGFR overexpression, age over 60 years, and Karnofsky performance score below 40 points did not significantly shorten survival time. In conclusion, the present study identified immunohistochemically detected mdm2-protein overexpression as a statistically significant negative prognostic parameter in patients bearing anaplastic or malignant glioma. Association analysis of variables revealed a possible correlation between mdm2 and p53, which is also consistent with the biological interaction mode of both proteins in vivo.

Epidural electrical stimulation of the motor cortex in patients with facial neuralgia.

Chronic facial neuralgias often do not respond sufficiently to standard treatment methods. Alternative modalities are needed for long-term reduction of pain in such cases. The present preliminary report describes two patients with trigeminal and glossopharyngeal neuralgia, respectively, treated with standard methods without obtaining satisfactory pain relief. Electrical stimulation of the motor cortex contralateral to the pain area was employed in both cases and proved able to produce a long-term facial pain reduction. Alleviation of pain occurred after activation of the flat quadripolar electrode placed epidurally on the precentral cortical area and lasted as long as the stimulator was working. By changing the polarity of the electrodes, it was possible to induce tingling sensations and muscle activation not only contralaterally to the stimulated motor cortex, but also in the ipsilateral part of the face. No stimulator-independent pain reduction resulted from long-term use of the stimulation device. During a follow-up period of 18 months, a sufficient and relatively stable analgesic effect of electrostimulation was observed. One major complication of motor cortex stimulation during the follow-up period was a single generalized epileptic seizure in one of the patients.

Continuous monitoring of the partial pressure of oxygen in cerebral venous blood.

OBJECTIVE: Clinical oxygen monitoring in the injured brain is somewhat difficult. However, ischemia is one of the major factors responsible for secondary tissue damage after head injury or subarachnoid hemorrhage. Therefore, the aim of the present study was to investigate the value of continuously monitoring the partial pressure of oxygen in cerebral venous blood (PcvO2) during changes in intracranial pressure (ICP). METHODS: In eight domestic pigs with Clark type probes placed in the posterior third of the superior sagittal sinus, PcvO2 was continuously registered while ICP was stepwise elevated by an inflatable balloon placed below the tentorium. Arterial blood pressure was continuously monitored, cerebral perfusion pressure (CPP) was calculated, and arterial partial carbon dioxide pressure and partial pressure of oxygen were registered intermittently. RESULTS: The mean intraparenchymal ICP before the start of balloon inflation was 5 +/- 1 mm Hg, the mean CPP was 80 +/- 15 mm Hg, and the mean PcvO2 was 36 +/- 3 mm Hg. At maximum ICP elevation, CPP decreased to 20 +/- 12 mm Hg, PcvO2 decreased to 10 +/- 6 mm Hg, and ICP increased to 90 +/- 10 mm Hg. Strong linear correlations between ICP and PcvO2 and between CPP and PcvO2 were revealed, and mean correlation coefficients of 0.89 for ICP/PcvO2 and 0.73 for CPP/PcvO2 were calculated. CONCLUSION: The present study demonstrates that polarographic PcvO2 monitoring in the superior sagittal sinus is a reliable method for the early detection of reduced CPP during ICP elevation. This technique is capable of registering the global oxygen supply and oxygen consumption of the brain. It seems superior to jugular venous oxymetry and is better suited for clinical use because of a somewhat low artifact susceptibility.

[Continuous measurement of jugular venous blood gas. A case of subarachnoid bleeding]. / Kontinuierliche Messung der jugularvenösen Blutgase. Ein Fall von Subarachnoidalblutung.

INTRODUCTION: Recently, a compact multisensor device 0.5 mm in diameter has become available with a miniaturised Clark electrode for measuring blood oxygen tension and two optical fibres for measuring CO2 tension, pH, and temperature (Paratrend 7, Biomedical Sensors, High Wycombe, UK). We used this new probe for continuous blood gas monitoring in the jugular bulb as an alternative to the commonly used fiberoptic spectrophotometric oximetric measurement of haemoglobin saturation. RESULTS: A 64-year-old patient was admitted for surgery of a right-sided intracranial aneurysm. During surgery, with no artefacts or evidence of catheter drift, a normal jugular venous pO2 (pjvO2) of 39 +/- 3 mmHg was measured. Over the period of weaning, two declines in pjvO2 occurred (22.5 and 18.7 mm Hg) associated with a decline in CO2 tension and a rise in pH. We treated these events successfully by analgosedation, controlled ventilation with an inspired oxygen fraction of 70%, and elevation of the mean arterial blood pressure to over 100 mmHg. Extubation was possible about 24 h later. Furthermore, 3 h after extubation pjvO2 values could be monitored without difficulty despite movement of the patient. DISCUSSION: The technique of polarographically measuring pjvO2 with a Clark-type probe appears superior to fibreoptic jugular venous oximetry due to the clearly lower incidence of faulty measurements, especially in the intensive care unit, where patients undergo frequent nursing interventions and tend to awaken. We did not even observe artefacts due to patient movement after extubation. A limitation of the new multisensor system might be the distance of 4 cm between the sensor tip and the end of the insertion catheter, which makes samples drawn for in vitro blood gas analyses to control the continuous monitoring less comparable. Improvements in the construction of the probe are recommended.