Venous collapse regulates intracranial pressure in upright body positions.

Recent interest in intracranial pressure (ICP) in the upright posture has revealed that the mechanisms regulating postural changes in ICP are not fully understood. We have suggested an explanatory model where the postural changes in ICP depend on well-established hydrostatic effects in the venous system and where these effects are interrupted by collapse of the internal jugular veins (IJVs) in more upright positions. The aim of this study was to investigate this relationship by simultaneous invasive measurements of ICP, venous pressure, and IJV collapse in healthy volunteers. ICP (monitored via the lumbar route), central venous pressure (peripherally inserted central catheter line), and IJV cross-sectional area (ultrasound) were measured in 11 healthy volunteers (47 ± 10 yr, mean ± SD) in 7 positions, from supine to sitting (0-69°). Venous pressure and anatomical distances were used to predict ICP in accordance with the explanatory model, and IJV area was used to assess IJV collapse. The hypothesis was tested by comparing measured ICP with predicted ICP. Our model accurately described the general behavior of the observed postural ICP changes (mean difference, -0.03 ± 2.7 mmHg). No difference was found between predicted and measured ICP for any tilt angle ( P values, 0.65-0.94). The results support the hypothesis that postural ICP changes are governed by hydrostatic effects in the venous system and IJV collapse. This improved understanding of postural ICP regulation may have important implications for the development of better treatments for neurological and neurosurgical conditions affecting ICP.

Long-term subarachnoid haemorrhage survivors still die due to cerebrovascular causes.

OBJECTIVE: Subarachnoid haemorrhage (SAH) is associated with sympathetic nervous activation and inflammation. SAH could therefore theoretically be a risk factor for development of cardiovascular disease. The aim of this study was to investigate whether long-term (≥1 year) SAH survivors had an increased risk of death due to cardiovascular causes. MATERIAL & METHODS: SAH patients ≥18 years treated at Umeå University Hospital between 1986 and 2006 were eligible for inclusion. Deceased patients were identified in the Swedish population register. Death certificates from long-term SAH survivors and causes of death in the general population were obtained from the National Board of Health and Welfare, Sweden. The prevalence of comorbidities at the time of SAH was compared with the distribution of cardiovascular risk factors in the northern Sweden MONICA (Multinational Monitoring of Trends and Determinants in Cardiovascular Disease) health survey. Analyses were stratified for age and sex. RESULTS: In the SAH patients, the median year of SAH was 1992 and the median year of death was 2001. The MONICA survey in 1994 and the distribution of deaths in the general population in 2001 were used for comparison. Long-term SAH survivors had, compared to the general population, a significantly increased risk for death due to cerebrovascular disease (P < 0.0001), but not for death due to cardiovascular disease. Hypertension was more common in SAH patients compared to survey participants (P < 0.01). CONCLUSION: Cerebrovascular causes of death were significantly more common in long-term survivors after SAH compared to the general population.

Severe traumatic brain injury management and clinical outcome using the Lund concept.

This review covers the main principles of the Lund concept for treatment of severe traumatic brain injury. This is followed by a description of results of clinical studies in which this therapy or a modified version of the therapy has been used. Unlike other guidelines, which are based on meta-analytical approaches, important components of the Lund concept are based on physiological mechanisms for regulation of brain volume and brain perfusion and to reduce transcapillary plasma leakage and the need for plasma volume expanders. There have been nine non-randomized and two randomized outcome studies with the Lund concept or modified versions of the concept. The non-randomized studies indicated that the Lund concept is beneficial for outcome. The two randomized studies were small but showed better outcome in the groups of patients treated according to the modified principles of the Lund concept than in the groups given a more conventional treatment.

Predicting improvement after surgery for palmar hyperhidrosis.

OBJECTIVES: Endoscopic transthoracic sympathectomy (ETS) is a surgical procedure used to improve Quality of Life (QoL) in patients with treatment resistant palmar hyperhidrosis (PHH). The aim of this study was to test the hypothesis that low preoperative scores on The Everyday Life Questionnaire (EDLQ) would predict QoL improvement after surgery. MATERIALS AND METHODS: Pre- and post-operative QoL scores from a series of 30 consecutive patients who underwent ETS at our institution were analyzed. RESULTS: Preoperative QoL scores was a significant predictor of post-operative improvement across all dimensions covered by the questionnaire. CONCLUSION: Preoperative low QoL can be used as a guide in selecting patients with most improved QoL after ETS.

Severe traumatic brain injury: consequences of early adverse events.

BACKGROUND: Several factors associated with an unfavourable outcome after severe traumatic brain injury (TBI) have been described: prolonged pre-hospital time, secondary referral to a level 1 trauma centre, the occurrence of secondary insults such as hypoxia, hypotension or low end-tidal carbon dioxide (ETCO(2)). To determine whether adverse events were linked to outcome, patients with severe TBI were studied before arrival at a level 1 trauma centre. METHODS: Prospective, observational study design. Patients with severe TBI (n = 48), admitted to Umeå University Hospital between January 2002 to December 2005 were included. All medical records from the site of the accident to arrival at the level 1 trauma centre were collected and evaluated. RESULTS: A pre-hospital time of >60 min, secondary referral to a level 1 trauma centre, documented hypoxia (oxygen saturation <95%), hypotension (systolic blood pressure <90 mmHg), hyperventilation (ETCO(2) <4.5 kPa) or tachycardia (heart rate >100 beats/min) at any time before arrival at a level 1 trauma centre were not significantly related to an unfavourable outcome (Glasgow Outcome Scale 1-3). CONCLUSION: Early adverse events before arrival at a level 1 trauma centre were without significance for outcome after severe TBI in the trauma system studied.

Cerebrospinal fluid dynamics and long-term survival of the Strata valve in idiopathic normal pressure hydrocephalus.

OBJECTIVE: Cerebrospinal fluid (CSF) dynamics and long-term shunt survival of the Strata CSF shunt were evaluated in patients with idiopathic normal pressure hydrocephalus (INPH). SUBJECTS AND METHODS: Seventy-two patients with INPH received a Strata valve. A CSF infusion test, neuroimaging and video recording of gait were performed at baseline and at 6 months (n = 68) after surgery. Long-term shunt survivals were obtained from patient records. RESULTS: The shunt survival at 1 year was 94% and at 3 years 92.5%. Forty-nine patients (72%) had an improved gait. Two patients were improved despite non-functioning shunts, indicating a possible placebo response. Nineteen patients were not improved at the 6-month follow-up. The shunt tests revealed a functioning shunt in 12; thus, unnecessary shunt revisions could be avoided. Seventeen patients showed a siphoning effect. Shunt revisions were made in six patients. Eight hygromas/subdural hematomas were found. CONCLUSIONS: The long-term survival of the Strata valves was good, and a concern of complications is not a reason to exclude elderly with INPH from shunt surgery. Studies are needed to evaluate pros and cons of the anti-siphon device. Using a CSF shunt test, unnecessary shunt revisions may be avoided.

S-100B and neuron specific enolase are poor outcome predictors in severe traumatic brain injury treated by an intracranial pressure targeted therapy.

OBJECTIVE: To prospectively study S-100B and neuron specific enolase (NSE) levels in subjects treated for severe head injury (sTBI), and investigate the prognostic value of these biomarkers. METHODS: Subjects included in a prospective double blind randomised study for sTBI. INCLUSION CRITERIA: Glasgow Coma Score (GCS) 10 mm Hg and arrival <24 h after trauma. Subjects were treated with an intracranial pressure (ICP) targeted therapy. Blood samples for S-100B and NSE were drawn immediately after arrival and every 12 h for 5 days. Outcome was evaluated as Glasgow Outcome Scale (GOS) by independent staff at 3 and 12 months. RESULTS: 48 subjects, mean age 35.5 years, and median GCS 6 were included. The first blood sample was drawn at 15.6 (1.4) h after injury. Initial concentration of S-100B was 1.04 (0.21) microg/l and for NSE 18.94 (2.32) microg/l. The biomarkers were significantly higher in subjects with GCS 3 and in those who died compared with those with GCS 4-8 and GOS 2-5, respectively. Receiver operated characteristic curve analyses of the initial S-100B and NSE levels to GOS dichotomised as unfavourable (GOS 1-3) and favourable (GOS 4-5) showed a weak correlation: AUC 0.585 and 0.555, respectively. Using the dichotomisation dead (GOS 1)/alive (GOS 2-5), the AUC values were 0.687 and 0.734, respectively. Furthermore, a correlation was found between the biomarkers themselves and the biomarkers and ICP. CONCLUSION: At 3 and 12 months after trauma, no differences in prognostic values between the markers were apparent nor was there any clinical significant value of the markers as predictors of clinical outcome.

Fluid therapy and the use of albumin in the treatment of severe traumatic brain injury.

BACKGROUND: Evidence-based guidelines for severe traumatic brain injury (TBI) do not include strategies for fluid administration. The protocol used in this study includes albumin administration to maintain normal colloid osmotic pressure and advocates a neutral to slightly negative fluid balance. The aim of this study was to analyze the occurrence of organ failure and the mortality in patients with severe TBI treated by a protocol that includes defined strategies for fluid therapy. METHODS: Ninety-three patients with severe TBI and Glasgow Coma Score or=3 was evident only for respiratory failure, which was observed in 29%. None developed renal failure. After 28 days, mortality was 11% and, after 18 months, it was 14%. CONCLUSIONS: A protocol including albumin administration in combination with a neutral to a slightly negative fluid balance was associated with low mortality in patients with severe TBI in spite of a relatively high frequency (29%) of respiratory failure, assessed with the SOFA score.

Long-term effect of deep brain stimulation for essential tremor on activities of daily living and health-related quality of life.

OBJECTIVES: To report long-term effects of thalamic deep brain stimulation (DBS) on activities of daily living (ADL) and health-related quality of life (HRQoL) in patients with essential tremor (ET). MATERIALS AND METHODS: Nineteen consecutive patients were evaluated at baseline, at a mean of 1 year, then at a mean of 7 years after DBS using Tremor Rating Scale, Mini Mental Test, ADL Taxonomy, Nottingham Health Profile, Life Satisfaction Checklist, Visual Analogue Scale and interview. RESULTS: There was a decrease of DBS efficacy on tremor between 1 and 7 years post-operatively. The marked improvement in ADL at 1 year was no longer sustained at long-term, except for the ability to eat. Social life remained improved. CONCLUSION: Although there is a decrease of DBS effect on tremor at 7 years, and even though further ageing and co-morbidities may impact on the well-being of patients, there is still relevant benefit of DBS on few aspects of ADL and HRQoL in patients with ET.

Sympathicotomy affects cutaneous blood flow, temperature, and sympathicus-mediated reflexes.

OBJECTIVE: To study the sympathetically mediated effects of transthoracic endoscopic sympathicotomy (TES) in the treatment of severe primary palmar hyperhidrosis. MATERIALS AND METHODS: The effects of TES, on sympathetic ganglia at the thoracic level of 2-3, finger blood flow, temperature, and on heat and cold provocation were investigated. Middle cerebral artery (MCA) blood flow velocities were studied by transcranial Doppler. RESULTS: The finger blood flow increased by about 700% after TES and finger temperature by 7.0 +/- 0.5 degrees C. Several autonomic reflexes were dramatically affected. A finger pulp-shrinking test showed a major decrease after surgery. MCA mean blood flow velocities were not affected by TES. CONCLUSIONS: Besides the high success rate of good clinical effect of TES on palmar hyperhidrosis, major effects on local blood flow and temperature are elicited by TES. Complex autonomic reflexes are also affected. The patient should be completely informed before surgery of the side effects elicited by TES.

Thalamic deep brain stimulation in the treatment of essential tremor: a long-term follow-up.

Deep brain stimulation (DBS) of the nucleus ventralis intermedius thalami (Vim) in the treatment of essential tremor (ET) is well documented concerning the acute effects. Reports of the long-term effects are, however, few and the aim of the present study was to analyse the long-term efficacy of this treatment. Nineteen patients operated with unilateral Vim-DBS were evaluated with the Essential Tremor Rating Scale (ETRS) before surgery, and after a mean time of 1 and 7 years after surgery. The ETRS score for tremor of the contralateral hand was reduced from 6.8 at baseline to 1.2 and 2.7, respectively, on stimulation at follow-up. For hand function (item 11 - 14) the score was reduced from 12.7 to 4.1 and 8.2, respectively. Vim-DBS is an efficient treatment for ET, also after many years of treatment. There is, however, a decreasing effect over time, most noticeable concerning tremor of action.

CSF pressure assessed by lumbar puncture agrees with intracranial pressure.

The accuracy of estimating intracranial pressure in brain tissue (ICP(BT)) via lumbar space was investigated using preset pressure levels in the interval 0 to 600 mm H(2)O in patients with communicating hydrocephalus. Lumbar space ICP correlated excellently to ICP(BT), demonstrated by a measured mean difference of 10 mm H(2)O (0.75 mm Hg) and a regression coefficient of 0.98. The concurrence supports the lumbar puncture as an accurate technique to determine ICP in patients with communicating CSF systems.

Smoking and non-smoking tobacco as risk factors in subarachnoid haemorrhage.

OBJECTIVE: Swedish snuff is a particular form of non-smoking tobacco with high nicotine content. It is unknown whether this form of tobacco is a risk factor similar to smoking for suffering subarachnoid haemorrhage (SAH). In the present study we report our finding concerning smoking and snuff as risk factors for the disease. METHOD: We analysed 120 consecutive patients with SAH regarding consumption of tobacco, in order to evaluate if snuff also is associated with an increased risk of SAH. RESULTS: The relative risk of SAH was about 2.5 times higher for smokers compared with the background population. Consumption of snuff was not associated with an increased risk. CONCLUSIONS: It seems unlikely that nicotine is solely responsible for the rupture of cerebral aneurysms. The final cause of the increased risk for suffering SAH has to be sought in other factors associated with tobacco smoking.

The Swedish Malignant Middle cerebral artery Infarction Study: long-term results from a prospective study of hemicraniectomy combined with standardized neurointensive care.

OBJECTIVES: Hemicraniectomy in patients with malignant middle cerebral artery (mMCA) infarct may be life-saving. The long-term prognosis is unknown. METHODS: Patients with mMCA infarct treated with hemicraniectomy between 1998 and 2002 at three hospitals were included. The criterion for surgical intervention was if the patients deteriorated from awake to being responding to painful stimuli only. All patients were followed for at least 1 year. Outcome was defined as alive/dead, walkers/non-walkers or modified Rankin Scale (mRS) score

Brain energy metabolism and intracranial pressure in idiopathic adult hydrocephalus syndrome.

BACKGROUND: The symptoms in idiopathic adult hydrocephalus syndrome (IAHS) are consistent with pathology involving the periventricular white matter, presumably reflecting ischaemia and CSF hydrodynamic disturbance. OBJECTIVE: To investigate whether a change in intracranial pressure (ICP) can affect energy metabolism in deep white matter. METHODS: A microdialysis catheter, a brain tissue oxygen tension probe, and an ICP transducer were inserted into the periventricular white matter 0-7 mm from the right frontal horn in 10 patients with IAHS. ICP and intracerebral Ptio2 were recorded continuously during lumbar CSF constant pressure infusion test. ICP was raised to pressure levels of 35 and 45 mm Hg for 10 minutes each, after which CSF drainage was undertaken. Microdialysis samples were collected every three minutes and analysed for glucose, lactate, pyruvate, and glutamate. RESULTS: When raising the ICP, a reversible drop in the extracellular concentrations of glucose, lactate, and pyruvate was found. Comparing the values during baseline to values at the highest pressure level, the fall in glucose, lactate, and pyruvate was significant (p < 0.05, Wilcoxon sign rank). There was no change in glutamate or the lactate to pyruvate ratio during ICP elevation. Ptio2 did not decrease during ICP elevation, but was significantly increased following CSF drainage. CONCLUSIONS: Raising intracranial pressure induces an immediate and reversible change in energy metabolism in periventricular white matter, without any sign of ischaemia. Theoretically, frequent ICP peaks (B waves) over a long period could eventually cause persisting axonal disturbance and subsequently the symptoms noted in IAHS.

Infusion technique can be used to distinguish between dysfunction of a hydrocephalus shunt system and a progressive dementia.

In a deteriorating shunted patient with hydrocephalus, an investigation of shunt function is often performed to distinguish a dysfunctioning shunt from an aggravated condition of the disease. The paper illustrates how a lumbar cerebrospinal fluid (CSF) infusion method can be used to evaluate post-operative deterioration in a shunted patient in order to give the physician valuable support in the shunt revision decision. A 77-year-old man with hydrocephalus was treated operatively by the insertion of a CSF shunt. Owing to shunt failure, the shunt was revised twice during a 5 year period. Using a computerised infusion technique method, with two needles placed in the lumbar subarachnoid space, the CSF dynamic system was determined pre- and post-operatively with the functioning as well as the dysfunctioning shunts. The data were verified with a bench-test of the extirpated CSF shunt. There was a significant difference in conductance G between CSF systems with an open shunt and CSF systems with no shunt or an occluded shunt (deltaG= 38 mm3 s(-1) kPa(-1), p = 0.014, n= 7, ANOVA). CSF dynamics investigations, with and without a shunt, can give valuable clinical support in the management of a deteriorating hydrocephalus patient. With further development of the lumbar infusion method moving towards easy-to-use equipment, there is potential for widespread clinical use.

CSF outflow resistance as predictor of shunt function. A long-term study.

OBJECTIVES: Little is known about the long-term impact of a CSF shunt on the human CSF hydrodynamic system. In patients with communicating hydrocephalus, patency of the shunt system is not regularly assessed. In order to reveal postoperative changes in the CSF hydrodynamic system, we prospectively investigated the features of the system in shunted patients with idiopathic adult hydrocephalus syndrome (IAHS) over a 3-year period. MATERIAL AND METHODS: Thirty-two patients with IAHS were studied at baseline and at 3, 9, 18 and 36 months postoperatively. All patients were operated on with a Hakim standard valve system and a ventriculo-peritoneal approach. At each visit, the patients were investigated with computed tomography/magnetic resonance imaging, video recording of gait and a lumbar constant pressure infusion method. Six brand-new Hakim valves were investigated in a bench test, and these results were compared with the in vivo results. RESULTS: After shunt insertion, the CSF outflow resistance was significantly decreased (13.6 vs 3.8 mmHg/ml/min). The mean outflow resistance of the six in vitro tested valves corresponded to the postoperative values. The variation in resistance in the functioning shunts at different postoperative investigations was negligible. The mean intracranial pressure in the supine position was 13.8 mmHg at the baseline and 14.3, 14.5, 14.8 and 15.7 mmHg at the follow-up visits, respectively. Postoperatively, the CSF pressure after sitting for 10 min (i.e. 'siphoning effect') decreased significantly (mean decrease -5.3, -5.4, -4.7 and -5.3 mmHg at each visit, respectively). Shunt-related complications occurred in seven patients (underdrainage four, overdrainage three). Despite a functioning shunt, eight patients never improved and another nine patients first improved but later deteriorated. CONCLUSIONS: The CSF outflow resistance is much decreased postoperatively and does not alter over time in patients with functioning shunts. We consider CSF outflow resistance to be a reliable indicator of shunt function and of fundamental importance to distinguish a dysfunctioning shunt from an aggravation of the primary condition in patients with communicating hydrocephalus. The unaltered intracranial pressure together with the in vitro model results, suggests that the intra-abdominal pressure might be a major determinant of the postoperative intracranial pressure.

Features of the Sinushunt and its influence on the cerebrospinal fluid system.

OBJECTIVES: A new cerebrospinal fluid (CSF) shunt system, Sinushunt, has recently been introduced. CSF is shunted from the ventricles to the transverse sinus. The Sinushunt is not a classical differential pressure shunt; instead, it opens as soon as there is a positive pressure over the shunt and the flow is dependent on the resistance of the system, which is high compared with traditional CSF shunts. The objective of this study was to characterise the features of the Sinushunt and to evaluate its influence on the CSF system. METHODS: Five brand new Sinushunts with distal catheters were tested. An automated, computerised experimental apparatus based on regulation of pressure, built into an incubator at 37 degrees C, was used. Opening pressure, resistance, and anti-reflux properties were determined. RESULTS: The mean (SD) opening pressure was highly dependent on the pressure in the sinus: P(open) = 1.3 (0.6) mm Hg with Psinus = 0.0 mm Hg, and Popen = 7.5 (0.6) mm Hg for Psinus = 6.5 mm Hg. The mean (SD) resistance of the shunts was 7.9 (0.3) mm Hg/ml/min and not clinically significantly affected by the sinus pressure. In one shunt there was reflux, and in another two shunts there was a very small, but similar, tendency. CONCLUSIONS: This study confirms that the resistance of the Sinushunt is comparable to the physiological values in humans. However, the optimal post-operative resistance for different hydrocephalus types is unknown, and randomised clinical trials are needed to confirm improved outcome and reduced complication rate for the Sinushunt compared with traditional low resistance ventriculoperitoneal shunts. A weakness of the anti-reflux system of the Sinushunt must be suspected and has to be further investigated.

An adjustable CSF shunt: advices for clinical use.

OBJECTIVES: The opening pressure and the resistance of a CSF shunt are essential for clinical use in order to set the proper opening pressure and to determine the shunt function in vivo. We find it of vital importance to validate and supplement the product description given by the manufacturer. The in vitro properties of a newly introduced, adjustable differential pressure valve with a siphon-preventing device (Strata valve) was compared with its predecessor (Delta valve). METHODS: An automated, computerized experimental set-up based on regulation of pressure, built into an incubator at 37 degrees C, was used. Opening pressure, resistance and siphon preventing properties were determined. Six brand-new shunts of each type with catheters were tested. The Delta valves were at a performance level of 1.5. RESULTS: The hydrodynamic properties of the Strata and Delta valves were similar. The anti-siphoning device was functioning for all valves. The estimated mean resistance for Delta and Strata shunts was 2.6 +/- 0.4 and 2.2 +/- 1.0 mmHg/ml/min, respectively. The mean opening pressure for the five performance levels of the Strata shunt are: 3.3, 5.1, 7.7, 10.7 and 13.1 mmHg. There may however, be considerable variations between the shunts. CONCLUSIONS: The Strata shunt is a properly working adjustable valve with anti-siphoning device that showed good reproducibility concerning opening pressure and resistance. At performance level 1.5, the new Strata shunt was similar to its predecessor concerning opening pressure and resistance. The given values of the different opening pressures and resistance could be used for in vivo testing of the valve function with a standard lumbar CSF infusion test.

Intracerebral microdialysis and CSF hydrodynamics in idiopathic adult hydrocephalus syndrome.

BACKGROUND: In idiopathic adult hydrocephalus syndrome (IAHS), a pathophysiological model of "chronic ischaemia" caused by an arteriosclerotic process in association with a CSF hydrodynamic disturbance has been proposed. OBJECTIVE: To investigate whether CSF hydrodynamic manipulation has an impact on biochemical markers related to ischaemia, brain tissue oxygen tension (PtiO(2)), and intracranial pressure. METHODS: A microdialysis catheter, a PtiO(2) probe, and an intracerebral pressure catheter were inserted into the periventricular white matter 0-7 mm from the right frontal horn in 10 patients with IAHS. A subcutaneous microdialysis probe was used as reference. Intracranial pressure and intracerebral PtiO(2) were recorded continuously. Samples were collected for analysis between 2 and 4 pm on day 1 (baseline) and at the same time on day 2, two to four hours after a lumbar CSF hydrodynamic manipulation. The concentrations of glucose, lactate, pyruvate, and glutamate on day 1 and 2 were compared. RESULTS: After CSF drainage, there was a significant rise in the intracerebral concentration of lactate and pyruvate. The lactate to pyruvate ratio was increased and remained unchanged after drainage. There was a trend towards a lowering of glucose and glutamate. Mean intracerebral PtiO(2) was higher on day 2 than on day 1 in six of eight patients. CONCLUSIONS: There is increased glucose metabolism after CSF drainage, as expected in a situation of postischaemic recovery. These new invasive techniques are promising tools in the future study of the pathophysiological processes in IAHS.