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Biomedical subjects

P Kehrli

Publications and source records attributed to P Kehrli.

At least 19 recordsLinked to original sources
PubMed2002

[Intracerebral radiation-induced cavernous angiomas].

We present four cases of cerebral cavernous angioma that developed after radiatherapy for brain tumor in three cases and for cavernous angioma in one case. The time interval between irradiation and the detection of the cavernous angioma varied from three to nine years and the doses from 24 to 60 Grays. Brain hemorrhage appeared in two cases. Explanation for the formation of cavernous malformations is unclear but is probably related to proliferation and dilatation of the vascular endothelium with formation of capillary telangiectasis with evolution to cavernous angiomas. The pediatric brain appears particularly vulnerable to radiation injury. The risk of hemorrhage appears higher than with spontaneous cavernous malformations.

Adolescent↗
PubMed2000

Language functional neuro-imaging changes following focal left thalamic infarction.

The involvement of the left thalamus in language function has been largely demonstrated through the effects of thalamic lesion and/or stimulation upon language. However, the pathophysiological mechanisms underlying thalamic aphasias remain a matter of debate. We report here on changes in the pattern of brain activity in auditory word processing, verb generation and visual lexical decision in a patient who sustained left thalamic infarct following the surgery of intractable mesio-temporal epilepsy with left hippocampal sclerosis. To some extent, our findings exemplify the way the left thalamus brings on line the cortical networks involved in language processing, suggested in the term 'selective engagement'.

Aphasia↗
PubMed2000

[Ophthalmic artery, optic nerve and meninges: reciprocal relations].

The origin of the ophthalmic artery exhibits several variants which can be explained by a vascular morphogenesis study. The particular relations of the ophthalmic artery with the optic nerve and the cranial meninges are examined using serial histological sections.

Gestational Age↗
PubMed2000

[Aspects of FLAIR sequences, 3D-CISS and diffusion-weight MR imaging of intracranial epidermoid cysts].

We propose to assess the usefulness of diffusion-weighted MR Imaging (DWI), fluid-attenuated inversion recovery (FLAIR) and constructive interference in steady state (CISS) sequences in depicting epidermoid cysts (EC). FLAIR, CISS and DWI were obtained in 7 patients among 22. All patients were studied with T1 and T2 sequences. On Spin Echo images, EC demonstrate signal similar to LCS, which may lead to difficult differentiation between EC and arachnoid cyst (AC), specially for inexperienced radiologists. EC appear with a heterogeneous signal on T1 images (32%), irregular limits (91%) and with extension through foramen of Pacchioni in 18% of cases. On FLAIR sequence, the tumors were heterogeneous, different from void signal of CSF in 86% of cases. On CISS sequence, the tumors appear heterogeneous, hyperintense but less than LCS and with irregular limits in all cases. Some more, CISS images allowed to appreciate exact tumor extension and their relations with nerves and vessels. On DWI images, signal is hyperintense in all cases. Our study exhibited the great usefulness of DWI, CISS and FLAIR sequences in diagnosis of EC and in differentiating EC from AC.

Brain Diseases↗
PubMed2000

[Spontaneous regression of an acute spinal subdural hematoma. MR imaging].

We report a case of acute spinal subdural hematoma which developed then regressed spontaneously. MR imaging contributed essential information for diagnosis and follow-up after conservative treatment. We made a short review of the literature and discuss the causes, pathogenesis, clinical presentation and usual treatment of acute spinal subdural hematoma. The differential diagnosis with the more frequent and extradural hematoma requiring immediate surgical evacuation is fundamental.

Aged↗
PubMed2000

[Contribution of 3D CISS MRI for pre- and post-therapeutic monitoring of obstructive hydrocephalus].

This report describes the use of the recent three-dimensional Fourier transform constructing imaging in the steady state (CISS) MR sequence in the management of obstructive hydrocephalus. It is a gradient-echo imaging technique with high resolution which remains sensitive to flow. It enables locating the obstruction and determining the upstream impact. It provides anatomical information about third ventricle (V3) morphology and relationships useful before ventriculostomy. Twenty patients with obstructive hydrocephalus at the level of cerebral aqueduct or posterior V3 underwent sagittal 3DFT-CISS acquisition, supplemented by frontal, axial and coronal reformations in the cerebral aqueduct axis. 9 patients were examined after ventriculostomy with the same protocol. CISS-3DFT allows good visualization of the cerebral aqueduct and diagnosis of the underlying cause of obstruction (malformation, tumor), sometimes better than classical sequences. In case of complete obstruction, the flow-related signal void is usually absent in the cerebral aqueduct or V3. The position of V3 floor and its relationship with the tip of basilar artery are well analyzed. The dilatation of the anterior V3 recesses is a better sign of activity of hydrocephalus - and then of therapeutical indication - than classical transependymal resorption signs which are not always present in chronic longstanding adult hydrocephalus. Of the 9 ventriculostomy patients seven had linear flow-related signal void through V3 floor, from anterior V3 to basal cisterns on the postoperative MR study. This flow void confirms patent ventriculostomy.

Adolescent↗
PubMed1999

Posterior extradural migration of extruded thoracic and lumbar disc fragments: role of MRI.

We report three patients with a sequestrated disc fragment posterior to the thecal sac. The affected disc was lumbar in two cases and thoracic in the third. Disc fragment migration is usually limited to the anterior extra dural space. Migration of a disc fragment behind the dural sac is seldom encountered. MRI appears to be the method of choice to make this diagnosis. The disc fragments gave low signal on T1- and slightly high signal on T2-weighted images and showed rim contrast enhancement. The differential diagnosis includes abscess, metastatic tumour and haematoma.

Diagnosis, Differential↗
PubMed1999

[Epidemiology of brain metastases].

The incidence of intracerebral metastasis is largely underestimated. They appear to be the most frequent cause of intracerebral tumors with an average incidence of probably more than 12/100 000 inhabitants per year. Depending on reports, 25 to 35% of cancer patients will develop brain metastasis. In neurosurgical series, the frequency of cerebral metastasis among surgical procedures for brain tumors increased from 3.5 to 12%. We reviewed the literature in order to better know the frequency of intracerebral metastasis depending on the type of primary cancer. The rate of other metastatic lesions, the duration between discovery of the primitive cancer and brain metastasis were found to be useful for selection of patients for neurosurgical treatment. Three types of cancers could be defined, regarding the incidence of brain metastasis. While occurrence of brain metastases is very high, surgery should often be useless; if brain metastases only occur in the late stage of a cancer, then, surgery should be discussed according to the general status of the patient; although brain metastasis is rare in a cancer, surgery will often be required for diagnosis and treatment.

Age Distribution↗
PubMed1999

[Biology of brain metastases: current concepts].

Brain metastasis results from complex interactions between host cells and primitive tumor cells. An analysis of the molecular pathways at the cellular level is provided in this review of the literature. The principal new therapeutic modalities are directly based on our comprehension of those molecular biology hypothesis.

Animals↗
PubMed1998

Is there a dural wall between the cavernous sinus and the pituitary fossa? Anatomical and MRI findings.

We compared MRI studies of the sellar area and embryological and adult histological studies of the cavernous sinuses and pituitary fossa. MRI studies were performed in 50 normal subjects with coronal sections using a fast inversion-recovery sequence to demonstrate the dural walls of the cavernous sinus and pituitary fossa. With this sequence, dura mater appears as a high-signal linear structure. The lateral and superior walls of the cavernous sinus was easily identified on all studies, but demonstration of a dural wall separating the cavernous sinus from the pituitary fossa was not possible. These results correlated well with embryological and adult histological studies obtained from 14 specimens. The absence of a strong separation between the pituitary fossa and the cavernous sinus explains the high incidence of extension of pituitary tumours to the cavernous sinuses and vice versa.

Adult↗
PubMed1998

[Cerebral risks in surgical position: position of the body, position of the brain].

The posture of the neurosurgical patient depends first on the approach and working position of the surgeon, and the spatial orientation during surgery. Venous outflow is probably the major factor for optimal brain retraction and for preventing venous haemorrhage. No one of the postures presently in use is fully free from the risk of air embolism. Respiratory and cardiac diseases are often limiting factors for the choice of a posture. Thoracic and abdominal compression must be cautiously avoided.

Brain↗
PubMed1998

[The sitting position in neurosurgery: the viewpoint of the surgeon].

The sitting position offers the benefits of better access to the apex of the posterior fossa, and an improved exploration and dissection because blood and cerebral spinal fluid drain away from the operative site. Specific complications of the sitting position include cardiovascular instability, jugular venous obstruction, airway oedema, quadriplegia, displacements of catheters and the endotracheal tube, ulnar, sciatic and lateral peroneal nerve compression, venous air embolism, and tension pneumocephalus. In the only existing comparative study, the differences were an increased bleeding in the horizontal position and a better cranial nerve preservation in the sitting position. This argues strongly for teaching and use of the sitting position whenever surgically indicated.

Humans↗
PubMed1998

[Surgery of the supratentorial and ventral spine: view-point of the surgeon].

The prone position for posterior fossa and cranio-spinal surgery is becoming the standard posture for neurosurgical teams. We analyze the reasons of such a change and specify indications of this posture. Thereafter, the procedure for optimal positioning is considered and the benefits of the prone position for the neurosurgeon and the anaesthetist are discussed. The selected references originate from Medline search (1991-1997), the Year Book of Neurology and Neurosurgery and the major neurosurgical review articles published between 1980 and 1996.

Humans↗
PubMed1998

[Intracranial surgery in the lateral position].

The lateral posture (Park Bench) is now widely used. It provides a comfortable position for the surgeon and a convenient brain relaxation. However the positioning is complex and carries a risk of stretching of the brachial plexus. Spatial orientation is more difficult and requires surgical experience. The lateral position does not modify the haemodynamic and respiratory function in healthy patients. In the opposite, various cardiac or respiratory effects of right or left lateral position can occur in patients with cardiac and/or respiratory pathology.

Anesthesia↗
PubMed1998

Anatomy and embryology of the lateral sellar compartment (cavernous sinus) medial wall.

In order to study the microanatomy of the lateral sellar compartment (cavernous sinus) medial wall, serial histological sections of human fetuses and adults, as well as dissections under operative microscope, were performed. The results were compared to high resolution Magnetic Resonance Images in human, to microdissections and to serial histological sections in adult nonhuman primates (Papio Cynocephalus anubis). We were able to show that the sellar compartment and both lateral sellar osteodural compartments are not separated from each other by a dural wall, but by a more or less dense, interrupted, fibrous tissue which derived from the mesenchyme surrounding the hypophysis, carotid artery, cranial nerves and venous channels. In the human fetus, the previous mentioned structures are located in a unique interperiosteodural space. Histoarchitecture of the superior and lateral wall dura-mater was different from the underlying mesenchyme derived connective tissue and was easily distinguished through histological examination. These findings correspond to MRI data. We conclude that there is no medial dural wall limiting the lateral sellar compartment (cavernous sinus), both parasellar and the hypophyseal compartment should be considered as a unique extradural space. The only dense connective tissue surrounding the pituitary gland is its own glandular capsule and the periosteum.

Adult↗