| 1. |
- Ljungqvist, Johan, et al.
(författare)
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Longitudinal study of the diffusion tensor imaging properties of the corpus callosum in acute and chronic diffuse axonal injury.
- 2011
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Ingår i: Brain injury. - : Informa UK Limited. - 1362-301X .- 0269-9052. ; 25:4, s. 370-378
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Tidskriftsartikel (refereegranskat)abstract
- Background: Magnetic resonance diffusion tensor imaging (MR-DTI) is used increasingly to detect diffuse axonal injury (DAI) after traumatic brain injury (TBI). Primary objective: The primary objective was to investigate the changes in the diffusion properties of the corpus callosum in the acute phase and 6 months after TBI and to examine the correlation between DTI parameters and clinical outcome. Research design: Longitudinal prospective study. Methods and procedures: MR-DTI was performed in eight patients with suspected DAI within 11 days and at 6 months post-injury. Six controls were also examined. Fractional anisotropy (FA), trace and parallel and perpendicular diffusivity of the corpus callosum were analysed. The main outcome was the extended Glasgow Outcome Scale score, assessed at 6 months. Main outcomes and results: A significant reduction in FA in the corpus callosum was seen in the acute phase in patients compared with the healthy controls. There was no significant change in the parallel or perpendicular eigenvalues or trace. At 6 months, a significant reduction in FA and a significant increase in trace and perpendicular eigenvalues were noticed compared with controls. Conclusions: The diffusion properties of the corpus callosum correlated with clinical outcome in this longitudinal investigation.
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| 2. |
- Shahsavari, Sima, 1976, et al.
(författare)
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A comparison between the transfer function of ABP to ICP and compensatory reserve index in TBI
- 2008
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Ingår i: Acta Neurochirurgica, Supplement. - Vienna : Springer Vienna. - 0065-1419. - 9783211855775 ; 102:102, s. 9-13
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: The transfer functions which map the arterial blood pressure to the intracranial pressure and the compensatory reserve index have been investigated by various groups to evaluate the brain compliance of patients with traumatic brain injury. The focus of this study has been to assess the capability of both the above mentioned methods to monitor the intracranial compliance in patients suffering from brain swelling. MATERIALS AND METHODS: Clinical data was collected from sixteen traumatic brain injury patients and split into 4 min segments. For each segment, both the magnitude of the empirical transfer function at the fundamental cardiac frequency and the compensatory reserve index were extracted. FINDINGS: The mean values of the compensatory reserve index and the magnitude of the transfer function which scored higher than 0.7 and 0.1 respectively were recorded for all patients suffering from brain swelling. By comparing the histogram of the magnitude of the transfer function at the fundamental cardiac frequency with the histogram of the compensatory reserve index for all patients, a positive correlation between the mean values and a negative correlation among their variances were observed. The linear correlation between the mean values was estimated at r = 0.82 (p
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| 3. |
- Shahsavari, Sima, 1976, et al.
(författare)
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Cerebrovascular Mechanical Properties and Slow Waves of Intracranial Pressure in TBI Patients
- 2011
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Ingår i: IEEE Transactions on Biomedical Engineering. - : Institute of Electrical and Electronics Engineers (IEEE). - 0018-9294 .- 1558-2531. ; 58:7, s. 2072-2082
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Tidskriftsartikel (refereegranskat)abstract
- Myogenic autoregulation of cerebral blood flow is one of the mechanisms affecting cerebral hemodynamics. Short or long-lasting changes in intracranial pressure (ICP) are believed to reveal the responses of the cerebral system to myogenic stimuli. Through the incorporation of a theoretical model into the experimental measurements of cerebrovascular distensibility and compliance in patients with traumatic brain injury (TBI), the current study is an attempt to explain ICP dynamics in either presence or absence of cerebral autoregulation. The pulse wave velocity and transfer function between arterial blood pressure and ICP were utilized as the major tools to reflect variations in the mechanical properties of distant cerebral artries/arteriols. The results imply that different states of cerebral autoregulation and associated regimes within the cerebrovascular system can lead to different types of interrelationship between the slow variations of ICP, cerebral arterial distensibility, and compliance. Consequently, each of these classes may require different types of treatment on patients with TBI.
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| 4. |
- Shahsavari, Sima, 1976, et al.
(författare)
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Normalized Power Transmission between ABP and ICP in TBI
- 2009
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Ingår i: Proceedings of the 31st Annual International Conference of the IEEE. Engineering in Medicine and Biology Society. - 9781424432967 ; , s. 4699-4703
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Konferensbidrag (refereegranskat)abstract
- A new approach to study the pulse transmission between the cerebrovascular bed and the intracranial space is presented. In the proposed approach, the normalized power transmission between ABP and ICP has got the main attention rather than the actual power transmission. Evaluating the gain of the proposed transfer function at any single frequency can reveal how the percentage of contribution of that specific frequency component has been changed through the cerebrospinal system. The gain of the new transfer function at the fundamental cardiac frequency was utilized to evaluate the state of the brain in three TBI patients. Results were assessed using the reference evaluations achieved by a novel CT scanbased scoring scheme. In all three study cases, the gain of the transfer function showed a good capability to follow the trend of the CT scores and describe the brain state. Comparing the new transfer function with the traditional one and also the index of compensatory reserve, the proposed transfer function was found more informative about the state of the brain in the patients under study.
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| 5. |
- Shahsavari, Sima, 1976, et al.
(författare)
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Plateau Waves and Baroreflex Sensitivity in Patients with Head Injury: A Case Study
- 2011
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Ingår i: Proceedings of the 33rd Annual International Conference of the IEEE. Engineering in Medicine and Biology Society. - 1557-170X. ; , s. 3792-3795
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Konferensbidrag (refereegranskat)abstract
- The study aimed to investigate baroreceptor reflex sensitivity in a patient with head injury for whom plateau waves of intracranial pressure (ICP) were recorded. Baroreflex sensitivity index was separately estimated on top of plateau waves and during intermediate intervals between two consecutive waves. The EuroBaVar data set was utilized to verify and validate the results. A very high baroreflex sensitivity associated with dominant parasympathetic activity was observed spontaneous to the acute elevations of ICP. The high vagal afferent discharge was found to be suggestive for the high firing rate of carotid baroreceptors and probably an active Cushing reflex mechanism during plateau waves.
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| 6. |
- Shahsavari, Sima, 1976, et al.
(författare)
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Pulse Wave Velocity in Patients with Severe Head Injury: A Pilot Study
- 2010
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Ingår i: Proceedings of the 32nd Annual International Conference of the IEEE. Engineering in Medicine and Biology Society. - 9781424441235 ; , s. 5277-5281
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Konferensbidrag (refereegranskat)abstract
- The study aimed to determine the potential of pulse wave velocity measurements to reflect changes in compliant cerebral arteries/arterioles in head injured patients. Theapproach utilizes the electrocardiogram and intracranial pressure signals to measure the wave transit time between heart and cranial cavity. Thirty five clinical records of nineteen head injured patients, with different levels of cerebrovascular pressurereactivity response, were investigated through the study. Results were compared with magnitude of normalized transfer function at the fundamental cardiac frequency. In patients with intact cerebrovascular pressure-reactivity, magnitude of normalized transfer function at the fundamental cardiac component was found to be highly correlated with pulse wave transit time.
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| 7. |
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| 8. |
- Skoglund, Thomas, 1969, et al.
(författare)
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Aspects on decompressive craniectomy in patients with traumatic head injuries
- 2006
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Ingår i: J Neurotrauma. - 0897-7151. ; 23:10, s. 1502-9
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Tidskriftsartikel (refereegranskat)abstract
- In patients with traumatic brain injury (TBI), intracranial hypertension secondary to cerebral edema is a major problem. A last-tier treatment in these cases is decompressive craniectomy. The aim of the present retrospective investigation was to (1) study the long-time outcome in patients with traumatic head injuries with intracranial hypertension treated with decompressive craniectomy; (2) examine the effects on intracranial pressure (ICP) by the craniectomy; and (3) investigate the possible relationship between the size of the removed bone-flap and the effects on ICP. Among the about 150 patients with severe TBI treated at our neurointensive care unit during 1997-2002, 19 patients were treated with decompressive craniectomy. All patients were young (mean 22 +/- 11 years, range 7-46 years), and 68% were male. The mean ICP was reduced from 29.2 +/- 3.5 before to 11.1 +/- 6.0 mm Hg immediately after the craniectomy; at 24 h after the craniectomy, the mean ICP was 13.9 +/- 9.7 mm Hg. Paired-samples t-test revealed a statistically significant decrease, both when comparing the preoperative values to the values immediately postoperative as well as to the values after 24 h (p < 0.01). A significant correlation between the size of the craniectomy and the decrease in ICP was found using Pearson regression analysis. The outcome of all patients could be assessed. The survival rate was 89%. Two patients died (both day 4 after the trauma); 68% of the patients had a favorable outcome (Glasgow Outcome Scale [GOS] score of 4 or 5); 16% were severely disabled (GOS score of 3); and one patient (5%) was left in a vegetative state.
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