Clinical Neuroscience

[Increasing cerebral perfusion pressure in serious cranial injury - contradictory effects of dopamine]

BARZÓ Pál, CZIGNER Andrea, ANTHONY Marmarou, ANDREW Beaumont, DEÁK Gábor, PANOS Fatouros, FRANK Corwin

JULY 10, 2005

Clinical Neuroscience - 2005;58(07-08)

[Background - Management of cerebral perfusion pressure is an important element of the treatment of traumatic brain injury. Vasopressors are accepted as a method of choice to increase mean arterial blood pressure and thus cerebral perfusion pressure in the face of rising intracranial pressure. There are, however, some unresolved issues and potential risks to this therapy. Matherial and methods - This study therefore examines the effects of dopamine on physiological changes as well as on brain edema and water content that can be readily assessed by MRI/MRS in 1. a rodent model of rapidly rising intracranial pressure, caused by diffuse injury with secondary insult and 2. a model of cortical contusion. Results - Dopamine was capable of restoring cerebral perfusion pressure in the model of rapidly rising intracranial pressure. However, this was associated with only a partial restoration of cerebral blood flow. In the brain tissue two profiles of change in the apparent diffusion coefficient of water (ADCw) were seen; one in which ADCw recovered to baseline, and one in which ADCw remained persistently low. Despite that dopamine did not alter these profiles, MRI-assessed tissue water content was increased four hours after injury and dopamine increased cerebral water content in both subgroups of injury, especially in the subgroup with a persistently low ADCw (p<0,01). In the contusion group dopamine significantly worsened the edema both in the injured and in the contralateral area of hippocampus and temporal cortex even though the ADCw values did not change, except for the contralateral hippocampus, where both water content and ADCw values rose with treatment, suggesting extracellular accumulation of water. Conclusion - The results suggest that dopamine has a double effect - while it temporarily and partially restores cerebral blood perfusion, at the same time it induces an increase in brain swelling and thus an increase in intracranial pressure in some cases. It is possible that in a subgroup of patients vasopressor treatment leads to an opposite effect several hours later. Vasopressor therapy in the clinical setting therefore should be cautiously applied.]

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Clinical Neuroscience

[Frontotemporal dementia - Part II Differential diagnosis, genetics, molecular pathomechanism and pathology]

GALARIOTIS Vasilis, BÓDI Nikoletta, JANKA Zoltán, KÁLMÁN János

[This is a comprehensive paper in three parts covering history, prevalence, clinical forms, differential diagnosis, genetics, molecular pathomechanism, pathology, clinical diagnosis and treatment of frontotemporal dementia (FTD). The second part focuses on the differential diagnosis, genetics, molecular pathomechanism and pathology. The clinical diagnosis of frontotemporal dementia is based on the presence of a prominent disturbance of the executive function and of frontal lobe syndrome or a progressive aphasic syndrome without severe global cognitive impairment. Of other dementias, it is primarily Alzheimer’s disease that it should be differentiated from, but other psychiatric disorders must also be ruled out. The disease has familial and sporadic forms. Recent identification of mutations in the gene encoding the microtubule-associated tau protein in the inherited frontotemporal dementia and parkinsonism linked to chromosome 17 (FTDP-17) has demonstrated that various tau dysfunctions can lead to neurodegeneration. Tau gene mutations have varied effects on the biology and function of the protein. This heterogeneous pathomechanism explains the wide range of clinical and neuropathological features observed in the FTDP-17. Tau and ubiquitin antibodies can be detected by sensitive immunohistochemical methods. The diagnosis of FTD should be based on neuropathological examination, and this is also the only method by which it can be definitely differentiated from other types of dementias.]

Clinical Neuroscience

[ELECTROPHYSIOLOGICAL SIGNS OF STRUCTURAL CHANGES IN MOTOR UNITS AFTER ISCHAEMIC STROKE]

LUKÁCS Miklós

[Introduction - While it is several decades ago that electrophysiological studies in the early stages after an ischaemic stroke revealed spontaneous activity in the affected muscles, today few data are available on the peripheral changes in later stages after a cerebrovascular event. The aim of this study was to detect electrophysiological signs that could indicate changes at the motor unit level occurring within a longer post-stroke period. Patients and methods - Forty-four patients who had developed hemiparesis after an ischaemic stroke in the area of the middle cerebral artery were involved in the study. Motor and sensory nerve conduction studies and electromyography were carried out on each side on six nerves and in five muscles respectively. Values between the affected and unaffected side were compared by statistical methods. Results - In patients with hemiparesis present for less then nine months, low M wave amplitudes, fibrillation potentials and an increased number of complex motor unit potentials were found on the affected side; in patients with symptoms present for more then nine months the mean duration and size index of the motor unit potentials in the paretic abductor digiti minimi muscle were increased. These data suggest a process of neurogenic type. The signs of distal axonal damage observed in the early period after stroke have been replaced later by chronic neurogenic changes. These changes could be the consequence of spinal motor neuron damage and axonal transport disturbance due to the loss of supraspinal trophic inputs. Conclusion - The correlation between the extent of electrophysiological changes and of the central motor deficit of the patient indicates the importance of delaying this process by appropriate rehabilitation procedures.]

Clinical Neuroscience

[Investigation of cerebral autoregulation in Parkinson’s disease]

DEBRECZENI Róbert, AMREIN Ilona, KOLLAI Márk, LÉNÁRD Zsuzsanna, PÁLVÖLGYI László, TAKÁTS Annamária, GERTRÚD Tamás, SZIRMAI Imre

[Background and purpose - The frequent orthostatic intolerance in Parkinson’s disease could be the consequence of cardiovascular autonomic failure and/or a damaged cerebral autoregulation (AR). To clarify this question the regulation of cerebral circulation was investigated by polygraphic method. Methods - On a tilt table simultaneous and continuous registrations were made of MCA velocity (VMCA) by transcranial Doppler, arterial blood pressure by non-invasive method, and end-tidal CO2, in supine and in tilted positions of 10°, 30°, 70° grades. The cerebral autoregulation was characterized by the slope of the curve of the arterial blood pressure at the level of the Willis-circle (BPW, as MCA perfusion pressure) plotted against the MCA velocity, achieved by linear regression (y=ax+b function, a=AR, or index of autoregulation). Patients - The data of 17 parkinsonian patients (PP) and eight age-matched controls (C) were analyzed. Results - The decrease of blood pressure in parkinsonian patients was significantly lower than in the controls when supine position was restored from 70° (ΔABP 70°-0°PP= -3.1±7.5 Hgmm; ΔABP 70°-0C°=-11.1±7.3 Hgmm; p<0.05), which suggests a damage to the sympathetic cardiovascular system. A disturbance of the cerebral autoregulation in patients was suggested by a progressively decreasing MCA average velocity (VMCA) during graded tilt, which was significiant at 70° (ΔVACM=9.8±8.82% cms-1; pCPP <0,05), and by a higher slope of pressure-velocity curve (ARC=0.143±0.125% cms-1/Hgmm; ARPP=0.38±0.25% cms-1/Hgmm; pC-PP<0.05). Conclusions - The results show that the cerebral blood flow of patients is more dependent on perfusion pressure compared to healthy controls. The disturbance of the sympathetic cardiovascular system and of cerebral autoregulation could be the consequence of a damage to the postganglionic structures in Parkinson’s disease. These results could explain the frequent orthostatic intolerance of patients even with normal blood pressure.]

Clinical Neuroscience

[125I brachytherapy of pineal parenchymal tumours]

JULOW Jenő, VIOLA Árpád, MAJOR Tibor, VALÁLIK István, SÁGI Sarolta, MANGEL László, KOVÁCS Rita Beáta, HÁVEL János, KISS Tibor

[Introduction - Pineal parenchymal tumours make up 0,3% of all brain tumours. Stereotactic biopsy has by now become an indispensable method to detect these tumours and it can be safely performed. Patients and method - Two patients with pineoblastoma were treated with 125I brachytherapy. The MRI and CT images taken 15 and 18 months after irradiation showed significant tumour shrinkage. Results - Tumour volume was 0.76 cm3 in the control CT image in Case 1, a shrinkage by 73% compared to 2.87 cm3 measured at the time of planning the interstitial irradiation. In Case 2, tumour volume measured on the control MRI examination was 0.29 cm3 as opposed to 1.27 cm3 of original tumour volume, which represents a 77% shrinkage. Conclusion - The insertion of isotope seeds was performed at the same time as the biopsy, because thus the knowledge of the histological diagnosis could spare the patients from a second stereotactic intervention. The CT- and image fusion guided 125I stereotactical brachytherapy is a procedure that can be dosimetrically precisely planned and surgically accurately and safely performed.]

Clinical Neuroscience

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LENGYEL András, LAKOS Gabriella, SIPKA Sándor, HEGEDÛS Katalin

[The stiff-man syndrome is a rare neurological disorder characterized by progressive stiffness of the axial muscles and co-contraction of agonist and antagonist muscles sometimes accompanied by involuntary sudden muscle spasms. The disease is thought to be caused by immunological changes leading to a GABA transmission disturbance, but the precise pathogenesis is not clear. Two Hungarian cases are presented in this article accompanied by a review of the literature. The aim of the paper is to call the attention on this presumably underdiagnosed disease. The diagnostic laboratory tests of the disease are available in Hungary.]

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[A NEW SURGICAL TECHNIQUE FOR THE TREATMENT OF SEVERE BRAIN EDEMA OF TRAUMATIC ORIGIN - RESULTS OF THE APPLICATION OF VASCULAR TUNNELS]

CSÓKAY András

[INTRODUCTION - Decompressive craniectomy with durotomy is a well known, although strongly disputed method of treatment in cases of brain trauma, brain swelling and during persisting danger of fatal incuneation. It is not without significance that literature mentions this method only as an option. Although the method successfully diminishes the ICP this can still result in a partial or total lesion occuring in the herniating part of the brain. The actual cause of these symptoms is found in the blockage of the veins and arteries, caused by the shear and the pressure forces between the dural edge and brain tissue. PATIENTS AND METHODS - The new surgical technique consists of the creation of a vascular tunnel around the main cortical veins and the arteries of herniated brain. 36 patients have been operated on with this method. We used historical control (28 patients treated conservatively, 20 patients treated with decompressive craniotomy). RESULTS - A retrospective comparison was performed and the results in connection with the mortality and morbidity rate was promising. CONCLUSION - With the help of our new technique we managed not only to reduce the ICP greatly but we could also avoid further vascular laesion. This is due to the fact that we can assure the circulation and veinous drainage of the herniated part of the brain. This method can be used in any severe edematous state generated by other causes.]

Clinical Neuroscience

[Measurements of regional cerebral blood flow and blood flow velocity in experimental intracarnial hypertension: infusion via the cisterna magna in rabbits]

BARZÓ Pál, DÓCZI Tamás, CSETE Klára, BUZA Zoltán, BODOSI Mihály

[The cerebral blood flow velocity (CBFV), as measured by transcranial Doppler sonography (TCD) via the transorbital route in the intracranial segment of internal carotid artery (ICA), and the regional cerebral blood (volume) flow (rCBF) in the corresponding cortical areas, as measured by the hydrogen clearance technique, were determined in 8 New Zealand White rabbits undergoing cisterna magna infusion for elevation of the intracranial pressure (ICP). In the lower range of autoregulation, i. e. at perfusion pressures (PP) between 80 and 40 mm of mercury and even below this, the changes in (CBFV) and CBF showed a strong correlation (0,86) under conditions with standard PCO2 (PaCO2)=35+2 mm of mercury). Autoregulation was exhausted at 40 mm of mercury and the cerebrovascular resistance (CVR) was minimal. Below this PP, the CBF and CBV dropped sharply, whereas CVR, gradually increased, indicating that, despite the maximally dilated resistance vessels, the intracranial hypertension causes the vascular resistance to increase, possibly via blocking of the venous outflow. Our results confirmed that non-invasive and easily (even at the bedside) applicable measurements of CBFV changes could substitute the cumbersome and expensive isotope measurements of CBF in intracranial hypertension.]

Clinical Neuroscience

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[The study gives an overview on the regulation of cerebral water content and of brain volume. The molecular mechanisms of the development and resolution of various oedema forms are discussed in detail. The physiological and pathophysiological role of the recently discovered molecular water channel proteins aquaporin-1 (AQP1) and aquaporin-4 (AQP4) as well as the importance of central neuroendocrine regulation by vasopressin and atriopeptin are reviewed based on the relevant literature and personal studies. Quantitative water maps based on the combination of multicompartment- T2, diffusion weighted MRI and T1 studies have proven to be powerful tools for studying new drugs against brain oedema brought about by various neuropathological conditions and for testing their efficacy both in animal experimental and clinical conditions. Non-peptide vasopressin antagonists, atriopeptin agonists and drugs targeting AQP4 are potential new families of oedema-decreasing drugs.]

Clinical Neuroscience

[THE LANDMARKS OF THE MEASUREMENT OF CEREBRAL BLOOD FLOW]

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[History of the measurement of local cerebral blood flow may cover a period of one and a half centuries. Parallel forthcoming of both theoretical and technical development were the key elements of ensuing progress resulting in the present state, when by the aid of in vivo blood flow and metabolic maps, we can visualize locales of brain functioning and their interconnections. Two theoretical landmarks should be mentioned in this historic process. First, the work of Adolf Fick, as the starter of quantitative measurements in this field, and Seymour Kety’s model of a single, homogenously perfused tissue element. The solution of this model, in the form of Kety’s equation is still fundamental to present day blood flow mapping techniques. Among the numerous investigators over the past years, two Hungarian scientist can be named as major contributors. Kálmán Sántha made substantial studies with continuous registration of local cerebral blood flow by the aid of thermocouples, while Emil Pásztor invented the hydrogen clearance method for the measurement of local cerebral blod flow both in human and in animal studies.]