Magnetic resonance study of bulk and thin film EuTiO3.

Magnetic resonance spectra of EuTiO3 in both bulk and thin film form were taken at temperatures from 3-350 K and microwave frequencies from 9.2-9.8 and 34 GHz. In the paramagnetic phase, magnetic resonance spectra are determined by magnetic dipole and exchange interactions between Eu2+ spins. In the film, a large contribution arises from the demagnetization field. From detailed analysis of the linewidth and its temperature dependence, the parameters of spin-spin interactions were determined: the exchange frequency is 10.5 GHz and the estimated critical exponent of the spin correlation length is ≈0.4. In the bulk samples, the spectra exhibited a distinct minimum in the linewidth at the Néel temperature, T N ≈ 5.5 K, while the resonance field practically does not change even on cooling below T N. This is indicative of a small magnetic anisotropy ~320 G in the antiferromagnetic phase. In the film, the magnetic resonance spectrum is split below T N into several components due to excitation of the magnetostatic modes, corresponding to a non-uniform precession of magnetization. Moreover, the film was observed to degrade over two years. This was manifested by an increase of defects and a change in the domain structure. The saturated magnetization in the film, estimated from the magnetic resonance spectrum, was about 900 emu cm-3 or 5.5 µ B/unit cell at T = 3.5 K.

The influence of mild hypothermia on ICP, CPP and outcome in patients with primary and secondary brain injury.

Aim of this study was to examine the hypothesis that only a subgroup of patients with lesser primary brain damage after severe head injury may benefit from therapeutic hypothermia. We prospectively analysed 72 patients with severe head injury, randomized into groups with (n = 37) and without (n = 35) hypothermia of 34 degrees C maintained for 72 hours. The influence of hypothermia on ICP, CPP and neurological outcome was analysed in the context of the extent of primary brain damage. Patients with normothermia and primary lesions (n = 17) values: GCS on admission 5 (median), ICP 18.9 (mean), CPP 73 (mean), GOS 4 (median). Patients with normothermia and extracerebral hematomas (n = 20): GCS 4, ICP 16, CPP 71, GOS 3. Patients with hypothermia and primary lesions (n = 21): GCS 4,62, ICP 10, 81, CPP 78,1, GOS 4. Patients with hypothermia and extracerebral hematomas (n = 14): GCS 5, ICP 13.2, CPP 78, GOS 5. Hypothermia decreased ICP and increased CPP regardless of the type of brain injury. Hypothermia was not able to improve outcome in patients with primary brain lesions but this pilot study suggests that it significantly improves outcome in patients with extracerebral hematomas.

Stereotactic evacuation of spontaneous infratentorial hemorrhage with monitoring of intracerebral pressure.

INTRODUCTION: Based on our experience with stereotactic evacuation of spontaneous supratentorial hematomas this method has also been used for evacuation of spontaneous infratentorial hematoma by the transtentorial approach. MATERIAL AND METHOD: The authors present a series of 6 patients with spontaneous intracerebral hematomas evacuated by the frame-based stereotactic technique, with monitoring of intracranial pressure (ICP) during the stereotactic evacuation. This method was indicated in patients with stable neurological status according to Glasgow Coma Scale (GCS), more than 10. The frame-based stereotaxy with the Riechert-Mundinger apparatus with CT localisation of target and optimal trajectory was used. RESULTS: The presented values after stereotactic evacuation show reduction of the initial intraparenchymal ICP in all patients to values less than 20 mmHg. CONCLUSION: The measuring of the ICP and the analysis of dynamic changes during stereotactic evacuation suggest that this procedure can significantly reduce the ICP performed in connection with ICH and we believe that our results can improve management of patients with spontaneous infratentorial and supratentorial intracerebral hematoma. (Fig. 1, Ref. 21.).

"No-reflow" phenomenon as a cause of hypoperfusion after severe head injury?

INTRODUCTION: Severe head injuries are known to cause secondary ischaemic brain damage. Ischaemia may develop due to transtentorial herniation or due to increased intracranial pressure leading to decreased perfusion. Compression of the brain due to extracerebral haematoma may cause hypoperfusion as well. METHODS: 29 patients with postraumatic transtentorial herniation were studied. Haematoma was urgently removed in these patients and CT and SPECT was performed on the 1st and 5th postoperative day. 26 patients had hypoperfusion on SPECT in the vicinity of the previous haematoma. Only 9 of them, however, had ischaemia on CT. There were 11 patients in whom the previous ischaemia seen on SPECT improved on the follow up SPECT examination. 10 of them had a good treatment result. CONCLUSION: A possible mechanism of hypoperfusion caused by compression of the brain may be a kind of "no-reflow" phenomenon which is known from pathophysiology of classical brain ischaemia. Patients in whom the collateral blood flow overcomes the decreased perfusion in the microcirculation should have a better outcome. (Tab. 1, Fig. 1, Ref. 13).

Cerebral perfusion pressure and spect in patients after craniocerebral injury with transtentorial herniation.

We present a group of 29 consecutive head injured comatose patients with the syndrome of transtentorial herniation. All patients had urgent surgery and then continuous monitoring of ICP, CPP, blood pressure and jugular bulb oximetry was instituted. Two postoperative CT and SPECT examinations were performed in each patient. 15 patients had a normal CPP (> 70 mmHg) throughout the postoperative period, 80% of them had a favourable outcome. On the other hand 14 patients had decreased CPP lasting at least one hour and only 36% of them had a favourable outcome (p < 0.05). Similar relationships were found comparing GOS in patients with normal and increased ICP (> 20 mmHg) and normal and decreased SjO2 (< 55%). All but 3 patients had ischaemia on SPECT. Ischaemia improved on the 2nd SPECT in 11 patients and 10 (91%) of them had a favourable outcome. GOS (mean follow up 9 months) is: 12 patients good, 5 moderately disabled, 2 vegetative, 10 died. We conclude that SPECT is able to disclose even reversible ischaemic changes. In these patients all effort has to be made to keep CPP on normal levels. Improvement in cerebral perfusion is related to a better outcome.

[A simple stereotaxic surgical apparatus]. / Jednoduchý stereotaktický operacní prístroj, SOP.

A simple apparatus based on the classical stereotactic method of surgery offers the opportunity to master miniinvasive procedures in neurosurgery and neurotraumatology. This device is particularly helpful in evacuation of intracerebral spontaneous and traumatic haematomas and in stereobiopsies, i.e. the most frequent operations in clinical practice, without the need of general anaesthesia, craniotomy and interference with cerebral tissue. The reliability of the stereotactic apparatus was positively evaluated by three independent surgeons. The apparatus was registered for use in the health services.

[Traumatic intracranial hemorrhage with a clinical temporal conus syndrome]. / Traumatické nitrolební krvácení s klinickým syndromem temporálního konusu.

The authors investigated a consecutive group of 14 patients treated at the Neurosurgical Clinic on account of traumatic intracranial haemorrhage, admitted with the clinical temporal conus syndrome (GCS 3-5, ipsilateral or bilateral mydriasis, failure of vital functions). All had emergency operations and at the intensive care unit the cerebral perfusion pressure and the saturation in the jugular bulb was monitored continuously. On the first and fifth day after surgery a check-up CT and SPECT examination was made. Only two patients had ischaemia during the first CT check-up, while 11 patients had impaired perfusion on the first SPECT. Improving perfusion on the check-up SPECT was the sign of a favourable prognosis, while ischaemia on the first CT was in both instances fatal. The Glasgow Outcome Score (GOS) six months after the injury was as follows: 9 patients had a good result, 2 patients were moderately disabled 3 patients died. The authors consider the following as basic prerequisites of a favourable outcome: not only early operation but also monitoring and treatment of impaired cerebral perfusion.

[Minimally invasive treatment of traumatic cerebral hematoma. Further experience with stereotaxic evacuation]. / Minimálne invazivní zpusob osetrení traumatických hematomu mozku. Dalsí zkusenosti se stereotaktickou evakuací.

The authors summarise their experience with 16 post-traumatic cerebral haematomas which they evacuated using stereotactic technique. Based on the achieved results they reached the conclusion that stereotactically aimed treatment of haematomas is an advance, for the patient's benefit. The evacuation cannula is safely inserted to its target from a transcutaneous drill hole of the skull and thus the patient is spared the surgical trauma associated with craniotomy and further brain damage. If necessary, the focus of haemorrhage can be reached again by puncture via the channel in the bone which navigates the cannula. Surgery under local anaesthesia is rapid and the results of promising. Extension of the new method depends, however, on the availability of simple stereotactic equipment which starts to play a part in the surgery of traumatic haematomas.