Cerebral Hemodynamics During Exposure to Hypergravity (+Gz) or Microgravity (0 G).

BACKGROUND: Optimal human performance and health is dependent on steady blood supply to the brain. Hypergravity (+Gz) may impair cerebral blood flow (CBF), and several investigators have also reported that microgravity (0 G) may influence cerebral hemodynamics. This has led to concerns for safe performance during acceleration maneuvers in aviation or the impact long-duration spaceflights may have on astronaut health.METHODS: A systematic PEO (Population, Exposure, Outcome) search was done in PubMed and Web of Science, addressing studies on how elevated +Gz forces or absence of such may impact cerebral hemodynamics. All primary research containing anatomical or physiological data on relevant intracranial parameters were included. Quality of the evidence was analyzed using the GRADE tool.RESULTS: The search revealed 92 eligible articles. It is evident that impaired CBF during +Gz acceleration remains an important challenge in aviation, but there are significant variations in individual tolerance. The reports on cerebral hemodynamics during weightlessness are inconsistent, but published data indicate that adaptation to sustained microgravity is also characterized by significant variations among individuals.DISCUSSION: Despite a high number of publications, the quality of evidence is limited due to observational study design, too few included subjects, and methodological challenges. Clinical consequences of high +Gz exposure are well described, but there are significant gaps in knowledge regarding the intracranial pathophysiology and individual hemodynamic tolerance to both hypergravity and microgravity environments.Saehle T. Cerebral hemodynamics during exposure to hypergravity (+Gz) or microgravity (0 G). Aerosp Med Hum Perform. 2022; 93(7):581-592.

A double-blind randomized trial on the clinical effect of different shunt valve settings in idiopathic normal pressure hydrocephalus.

OBJECTIVE: The study aim was to examine the effect of gradually reducing the opening pressure on symptoms and signs in the shunt treatment of idiopathic normal pressure hydrocephalus (iNPH). METHODS: In this prospective double-blinded, randomized, controlled, double-center study on patients with iNPH, a ventriculoperitoneal shunt with an adjustable Codman Medos Valve was implanted in 68 patients randomized into 2 groups. In 1 group (the 20-4 group) the valve setting was initially set to 20 cm H2O and gradually reduced to 4 cm H2O over the course of the 6-month study period. In the other group (the 12 group), the valve was kept at a medium level of 12 cm H2O during the whole study period. All patients were clinically evaluated using 4 tests preoperatively as well as postoperatively at 1, 2, 3, 4, and 6 months. The test scores between the 2 groups (20-4 and 12) were compared for each clinical evaluation. RESULTS: Fifty-five patients (81%) were able to complete the study. There were no significant differences between the 2 groups (20-4 and 12) preoperatively or at any time postoperatively. Both groups exhibited significant clinical improvement after shunt insertion at all valve settings compared with the preoperative score, with the greatest improvement observed at the first postoperative evaluation. The clinical improvement was significant within the first 3 months, and thereafter no significant improvement was seen in either group. CONCLUSIONS: Gradual reduction of the valve setting from 20 to 4 cm H2O did not improve outcome compared with a fixed valve setting of 12 cm H2O. Improvement after shunt surgery in iNPH patients was evident within 3 months, irrespective of valve setting.

Characteristics of intracranial pressure (ICP) waves and ICP in children with treatment-responsive hydrocephalus.

BACKGROUND: One important goal of modern treatment of pediatric hydrocephalus is to normalize the intracranial pressure (ICP) and ICP volume reserve capacity to optimize normal brain development. Better knowledge of the characteristics of ICP waves/ICP in pediatric hydrocephalus may provide new insight into the mechanisms behind modern hydrocephalus treatment. The aim of the present work was to characterize the ICP waves/ICP in children with either communicating or non-communicating hydrocephalus who improved clinically after surgery. The hydrocephalic children not treated surgically following ICP monitoring served as reference patients. METHODS: The patient material includes all children with hydrocephalus and no previous surgical treatment who underwent diagnostic ICP wave/ICP monitoring during the period 2002-2011. We retrieved the information about the patients from the patient records and the digitally stored ICP waveforms. The ICP wave characteristics amplitude, rise time and rise time coefficient and the mean ICP were determined in the patients treated surgically for their hydrocephalus. The findings were compared with findings in children not treated surgically after ICP monitoring who served as reference patients. RESULTS: The patient material includes 58 patients. Thirty-one (53%) were treated surgically after ICP monitoring, of whom all improved clinically. As compared to the reference patients, patients treated surgically presented with increased ICP wave amplitudes (MWA) and mean ICP. Alterations were comparable in communicating and non-communicating hydrocephalus. We found no apparent association between the ICP wave/ICP scores and presence of symptoms, indices of ventricular size or age. CONCLUSIONS: Children with either communicating or non-communicating hydrocephalus improving clinically after surgery presented with elevated MWA and mean ICP. In particular, the levels of MWA were raised to a magnitude seen when intracranial compliance is impaired. Hence, the present observations may support the idea that improvement of intracranial compliance can be an important mechanism by which shunts work in pediatric hydrocephalus.

Intracranial pressure monitoring in pediatric and adult patients with hydrocephalus and tentative shunt failure: a single-center experience over 10 years in 146 patients.

OBJECT In patients with hydrocephalus and shunts, lasting symptoms such as headache and dizziness may be indicative of shunt failure, which may necessitate shunt revision. In cases of doubt, the authors monitor intracranial pressure (ICP) to determine the presence of over- or underdrainage of CSF to tailor management. In this study, the authors reviewed their experience of ICP monitoring in shunt failure. The aims of the study were to identify the complications and impact of ICP monitoring, as well as to determine the mean ICP and characteristics of the cardiac-induced ICP waves in pediatric versus adult over- and underdrainage. METHODS The study population included all pediatric and adult patients with hydrocephalus and shunts undergoing diagnostic ICP monitoring for tentative shunt failure during the 10-year period from 2002 to 2011. The patients were allocated into 3 groups depending on how they were managed following ICP monitoring: no drainage failure, overdrainage, or underdrainage. While patients with no drainage failure were managed conservatively without further actions, over- or underdrainage cases were managed with shunt revision or shunt valve adjustment. The ICP and ICP wave scores were determined from the continuous ICP waveforms. RESULTS The study population included 71 pediatric and 75 adult patients. There were no major complications related to ICP monitoring, but 1 patient was treated for a postoperative superficial wound infection and another experienced a minor bleed at the tip of the ICP sensor. Following ICP monitoring, shunt revision was performed in 74 (51%) of 146 patients, while valve adjustment was conducted in 17 (12%) and conservative measures without any actions in 55 (38%). Overdrainage was characterized by a higher percentage of episodes with negative mean ICP less than -5 to -10 mm Hg. The ICP wave scores, in particular the mean ICP wave amplitude (MWA), best differentiated underdrainage. Neither mean ICP nor MWA levels showed any significant association with age. CONCLUSIONS In this cohort of pediatric and adult patients with hydrocephalus and tentative shunt failure, the risk of ICP monitoring was very low, and helped the authors avoid shunt revision in 49% of the patients. Mean ICP best differentiated overdrainage, which was characterized by a higher percentage of episodes with negative mean ICP less than -5 to -10 mm Hg. Underdrainage was best characterized by elevated MWA values, indicative of impaired intracranial compliance.

Association between ventricular volume measures and pulsatile and static intracranial pressure scores in non-communicating hydrocephalus.

BACKGROUND: In non-communicating hydrocephalus (HC), enlarged cerebral ventricles are often thought to reflect increased intracranial pressure (ICP) or increased pulsatile ICP. The present study was undertaken to explore the association between ventricular volume measures and pulsatile or static ICP scores in patients with non-communicating HC. Since linear measures of ventricular size have the most widespread use, we also examined how linear and volume measures of ventricular size compare. METHODS: The patient material includes all patients with non-communicating HC that underwent continuous over-night ICP monitoring during the period 2002-2011. The scores of pulsatile and static ICP were determined from the continuous ICP signals stored on the hospital server. Ventricular volume was determined both as linear measures of sectional CT or MR images and as 3D volume of all ventricles. We also determined the ventricular volume index as a relationship between ventricular volume and intracranial volume. RESULTS: Eighty-five patients were included in the study; they were dichotomized into those that previously had not received endoscopic third ventriculostomy (ETV; n=52; Group 1), and those that had previously underwent ETV (n=33; Group 2). None was previously shunted. We found no significant correlations between the ICP scores and the ventricular volume indices in neither of the patient groups. In Group 1, however, the mean ICP wave amplitude was significantly higher than in Group 2. There was a strong positive correlation between volume and linear measures of ventricular size. We found neither any association between age and ventricular volume; nor any association between ventricular volume and duration of symptoms. CONCLUSIONS: In this cohort of patients with non-communicating HC, we found no evidence of a proportional correlation between ventricular volume and pulsatile or static ICP. However, the findings suggest that symptomatic and untreated non-communication HC is still associated with reduced intracranial compliance.

A randomized controlled dual-center trial on shunt complications in idiopathic normal-pressure hydrocephalus treated with gradually reduced or "fixed" pressure valve settings.

OBJECT: This study was undertaken to investigate whether a gradual reduction of the valve setting (opening pressure) decreases the complication rate in patients with idiopathic normal-pressure hydrocephalus (iNPH) treated with a ventriculoperitoneal (VP) shunt. METHODS: In this prospective double-blinded, randomized, controlled, dual-center study, a VP shunt with an adjustable valve was implanted in 68 patients with iNPH, randomized into two groups. In one group (the 20-4 group) the valve setting was initially set to 20 cm H2O and gradually reduced to 4 cm H2O over the course of the 6-month study period. In the other group (the 12 group), the valve was kept at a medium pressure setting of 12 cm H2O during the whole study period. The time to and type of complications (hematoma, infection, and mechanical problems) as well as overdrainage symptoms were recorded. Symptoms, signs, and outcome were assessed by means of the iNPH scale and the NPH grading scale. RESULTS: Six patients in the 20-4 group (22%) and 7 patients in the 12 group (23%) experienced a shunt complication; 9 had subdural hematomas, 3 mechanical obstructions, and 1 infection (no significant difference between groups). The frequency of overdrainage symptoms was significantly higher for a valve setting ≤ 12 cm H2O compared with a setting > 12 cm H2O. The 20-4 group had a higher improvement rate (88%) than the 12 group (62%) (p = 0.032). There was no significant relationship between complications and body mass index, the use of an antisiphon device, or the use of anticoagulants. CONCLUSIONS: Gradual lowering of the valve setting to a mean of 7 cm H2O led to the same rate of shunt complications and overdrainage symptoms as a fixed valve setting at a mean of 13 cm H2O but was associated with a significantly better outcome.

Surgical site infections after deep brain stimulation surgery: frequency, characteristics and management in a 10-year period.

BACKGROUND/AIMS: Deep brain stimulation (DBS) implant infection is a feared complication, as it is difficult to manage and leads to increased patient morbidity. We wanted to assess the frequency and possible risk factors of DBS related infections at our centre. In the purpose of evaluating treatment options, we also analyzed treatment, and the clinical and microbiological characteristics of the infections. METHODS: Electronic medical records of all patients undergoing DBS surgery at our centre, from 2001 through 2010, were retrospectively reviewed. RESULTS: Of the 588 procedures performed 33 (5.6%) led to an infection. Some patients underwent several procedures, thus 32 out of totally 368 patients (8.7%), and 19 out of 285 patients (6.7%) who received primary lead implantation, developed an infection. Most infections (52%) developed within the first month and 79% within three months. In the majority of the infections (79%) hardware removal was performed. Staphylococcus aureus infections were the most frequent (36%), and more likely to have earlier onset, pus formation, a more aggressive development and lead to hardware removal. No risk factors were identified. CONCLUSIONS: Our results indicate that infections with more severe symptoms and growth of staphylococcus aureus should be treated with local hardware removal and antibiotic therapy. In other infections, an initial trial of antibiotic treatment could be considered. New knowledge about the microbiology of DBS related infections may lead to more effective antimicrobial treatment.

Long-term follow-up of thalamic deep brain stimulation for essential tremor - patient satisfaction and mortality.

BACKGROUND: Ventral intermediate thalamic nucleus (VIM) deep brain stimulation (DBS) is an effective treatment for tremor, but there is limited data on long-term efficacy and mortality after VIM-DBS. Here we report the analysis of patient satisfaction and mortality in all patients treated in our center 1996-2010 with VIM-DBS for essential tremor (ET). METHODS: Forty-six consecutive patients were included in this study. Medical records were reviewed, and a follow-up questionnaire was sent to all surviving patients. RESULTS: Seventy percent of all possible participants (26 patients) answered the questionnaire. Follow-up time for the responding patients was median 6.0 years (2-16). Median self-reported score on visual analogue scale of the initial postoperative effect on tremor was 8.5 (0.1-10), with a significant reduction to 7.4 (0-10) at follow-up (p = 0.001). Patients reported a median score of 10 (0-10) for overall patient satisfaction with VIM-DBS treatment. Eight patients (17%) died after median 8.9 years (0.6-15) after surgery, at median age 77.4 years (70-89). One patient (2%) committed suicide seven months after the operation. Calculated standard mortality ratio among ET patients was 1.3 (CI 0.6-2.6), similar to the general population. CONCLUSION: We found no significant increase in mortality in this cohort of VIM-DBS operated ET patients compared to the general population in Norway. The patients reported high long-term satisfaction and continuing effect of VIM-DBS on tremor even after many years. VIM-DBS therefore seems to be an effective symptomatic long-term treatment of ET. However, one patient committed suicide. Only one other suicide has previously been reported after VIM-DBS. It is therefore still unclear whether VIM-DBS increases suicide risk.

Local and systemic pro-inflammatory and anti-inflammatory cytokine patterns in patients with chronic subdural hematoma: a prospective study.

OBJECTIVE AND DESIGN: Innate immune pro- and anti-inflammatory responses in patients with chronic subdural hematoma (CSDH) were investigated by measuring and comparing the systemic and subdural fluid levels of cytokines. MATERIALS AND METHOD: Cytokine values were analyzed in samples obtained during surgery of 56 adult patients who were operated on for unilateral CSDHs using a Multiplex antibody bead kit. RESULTS: There were significantly higher levels of the pro-inflammatory IL-2R (p = 0.004), IL-5 (p < 0.001), IL-6 (p < 0.001), and IL-7 (p < 0.001), and anti-inflammatory mediators IL-10 (p < 0.001) and IL-13 (p = 0.002) in CSDH fluid compared with systemic levels. The pro-inflammatory TNF-alpha (p < 0.001), IL-1beta (p < 0.001), IL-2 (p = 0.007) and IL-4 (p < 0.001) were significantly lower in hematoma fluid compared with systemic levels. The ratios between pro- versus anti-inflammatory cytokines were statistically significant higher in CSDH (7.8) compared with systemic levels (1.3). CONCLUSIONS: The innate immune responses occur both locally at the site of CSDH, as well as systematically in patients with CSDH. The local hyper-inflammatory and low anti-inflammatory responses exist simultaneously. The findings suggest poorly coordinated innate immune responses at the site of CSDH that may lead to propagating of local inflammatory process and basically contribute to formation and progression of CSDH.

Chemokines as markers of local inflammation and angiogenesis in patients with chronic subdural hematoma: a prospective study.

OBJECTIVE: The goal of this study was to investigate the chemokines CCL2, CXCL8, CXCL9 and CXCL10 as markers of the inflammatory responses in chronic subdural hematoma (CSDH). METHODS: Samples of peripheral venous blood and CSDH fluid (obtained during surgery) in 76 adult patients were prospectively analyzed. Chemokine values were assessed by a Multiplex antibody bead kit. RESULTS: We found significantly higher levels of chemokines CCL2, CXCL8, CXCL9 and CXCL10 in hematoma fluid compared with serum. CONCLUSIONS: Chemokines are elevated in the hematoma cavity of patients with CSDH. It is likely that these signaling modulators play an important role in promoting local inflammation. Furthermore, biological activity of CCL2 and CXCL8 may promote neovascularization within the outer CSDH membrane, and a compensatory angiostatic activity of CXCL9 and CXCL10 may contribute to repairing this disorder. This phenomenon was restricted to the hematoma site, and the systemic chemokine levels might not reflect local immune responses.

Morphological characterization of cardiac induced intracranial pressure (ICP) waves in patients with overdrainage of cerebrospinal fluid and negative ICP.

Symptomatic overdrainage of cerebrospinal fluid (CSF) can be seen in shunted hydrocephalus patients and in non-shunted patients with spontaneous intracranial hypotension (SIH). In these patients, intracranial pressure (ICP) monitoring often reveals negative static ICP, while it is less understood how the pulsatile ICP (cardiac induced ICP waves) is affected. This latter aspect is addressed in the present study. A set of 40 ICP recordings from paediatric and adult hydrocephalus patients were randomly selected. Each cardiac induced ICP wave was automatically identified and manually verified by the beginning and ending diastolic minimum pressures and the systolic maximum pressure. The ICP wave parameters (static pressure, amplitude, rise time, rise time coefficient, downward coefficient, wave duration, and area-under-curve) were then automatically computed. The material of 40 ICP recordings provided a total of 3,192,166 cardiac induced ICP waves (1,292,522 in paediatric patients and 1,899,644 in adult patients). No apparent changes in ICP wave parameters were seen when mean ICP became negative, except that the parameters amplitude, rise time coefficient, downward coefficient and area under curve somewhat increased when mean ICP was below -15 mmHg.

Is ventriculomegaly in idiopathic normal pressure hydrocephalus associated with a transmantle gradient in pulsatile intracranial pressure?

PURPOSE: In patients with idiopathic normal pressure hydrocephalus (iNPH) and ventriculomegaly, examine whether there is a gradient in pulsatile intracranial pressure (ICP) from within the cerebrospinal fluid (CSF) of cerebral ventricles (ICP(IV)) to the subdural (ICP(SD)) compartment. We hypothesized that pulsatile ICP is higher within the ventricular CSF. METHODS: The material includes 10 consecutive iNPH patients undergoing diagnostic ICP monitoring as part of pre-operative work-up. Eight patients had simultaneous ICP(IV) and ICP(SD) signals, and two patients had simultaneous signals from the lateral ventricle (ICP(IV)) and the brain parenchyma (ICP(PAR)). Intracranial pulsatility was characterized by the wave amplitude, rise time, and rise time coefficient; static ICP was characterized by mean ICP. RESULTS: None of the patients demonstrated gradients in pulsatile ICP, that is, we found no evidence of higher pulsatile ICP within the CSF of the cerebral ventricles (ICP(IV)), as compared to either the subdural (ICP(SD)) compartment or within the brain parenchyma (ICP(PAR)). During ventricular infusion testing in one patient, the ventricular ICP (ICP(IV)) was artificially increased, but this increase in ICP(IV) produced no gradient in pulsatile ICP from the ventricular CSF (ICP(IV)) to the parenchyma (ICP(PAR)). CONCLUSIONS: In this cohort of iNPH patients, we found no evidence of transmantle gradient in pulsatile ICP. The data gave no support to the hypothesis that pulsatile ICP is higher within the CSF of the cerebral ventricles (ICP(IV)) than within the subdural (ICP(SD)) compartment or the brain parenchyma (ICP(PAR)) in iNPH patients.

Abductor pollicis longus tendon interposition for arthrosis in the first carpometacarpal joint: 55 thumbs reviewed after 3 (1-5) years.

We have performed an interposition arthroplasty using the abductor pollicis longus (APL) tendon for arthrosis in the basal joint of the thumb in our department since 1995. Before this, we had been using an interposition with the flexor carpi radialis (FCR) tendon. We re-examined 47 patients (55 thumbs) after a median follow-up of 41 (16-60) months. The pain relief was excellent in 32 thumbs, and 25 patients improved their ability to perform daily tasks. Mobility was well preserved. Key pinch and grip strengths averaged 78% and 89%, respectively, of those in unaffected hands. An excellent general result was reported by 34 patients, while 4 patients would not have consented to the operation if they had known the outcome in advance.