Optical properties of human brain tissue, meninges, and brain tumors in the spectral range of 200 to 900 nm.

Considering the increasing use of lasers in neurosurgery and the increasing number of wavelengths of laser light becoming available, we evaluated optical properties between 200 and 900 nm of meninges, normal human brain tissue, and brain tumors. We used a two-beam spectral photometer with an integrating sphere as the measuring instrument. The material consisted of 13 brains and 1 specimen each of dura mater, falx, and arachnoid obtained at autopsy and 30 samples of brain tumors removed during operation. In tissue samples more than 5 mm thick, the relative levels of absorption and scattering were estimated from the relative level of reflection measured according to the Kubelka-Munk theory. In thin tissue slices, penetration depth was calculated according to Beer's law from measurements of reflection and transmission. Generally, in all tissues there was an increase of reflection, scattering, and penetration depth and a decrease of absorption from the ultraviolet up to the near infrared spectral range interrupted by the absorption bands of hemoglobin. Within the ultraviolet spectral range, no major differences of optical properties were observed. Within the visible and near infrared spectral range, white matter reflected most of the incident power and showed the lowest level of absorption and the shortest penetration depth. Low grade gliomas revealed optical properties similar to those of gray matter. In comparison with normal brain tissue, meningiomas and glioblastomas showed significantly higher levels of absorption calculated according to the Kubelka-Munk theory from reflection measurements in thick tissue samples, but also deeper penetration obtained from measurements of reflection and transmission in thin slices, especially within the near infrared spectral range.

Time course and spatial distribution of neodymium: yttrium-aluminum-garnet (Nd:YAG) laser-induced lesions in the rat brain.

Cerebral lesions made by focal neodymium:yttrium-aluminum-garnet (Nd:YAG) laser irradiation of the rat forebrain were studied in adult Wistar rats. For the analysis of time-dependent changes, the brains of 28 animals were irradiated with a constant energy density of 461 J/cm2. In this series, survival time ranged from 0.5 hours to 80 days. Immediately after irradiation, a circular lesion appeared on the surface of the brain. This lesion was surrounded by an edematous area intensively stained with Evans blue. At energy levels higher than 30 J, this circular edema contained numerous thrombosed vessels. Histopathologically, the lesion consisted of three distinct zones: the central coagulation necrosis was surrounded by a zone of delayed colliquation necrosis and by perifocal edema. At approximately 80 days after irradiation, the resulting cortical defect was covered by a pial membrane. Edematous changes of the brain cortex and the adjacent white matter were observed as early as 1 hour after irradiation. Within 16 hours, the perifocal edema spread over the white matter of both hemispheres, and it had disappeared by the 5th day after irradiation. In a second experiment, the energy density varied from 231 to 3077 J/cm2. This series consisted of 84 animals that were allowed to survive 48 hours. The size of the lesion depended on the level of energy applied, but the depth of the lesion varied less than the diameter at the brain surface.(ABSTRACT TRUNCATED AT 250 WORDS)

Cerebrovascular and metabolic effects on the rat brain of focal Nd:YAG laser irradiation.

To investigate the effects of focal neodymium:yttrium-aluminum-garnet (Nd:YAG) laser irradiation (lambda = 1060 nm) on regional cerebral blood flow, cerebral protein synthesis, and blood-brain barrier permeability, the parietal brain surface of 44 rats was irradiated with a focused laser beam at a constant output energy of 30 J. Survival times ranged from 5 minutes to 48 hours. Laser irradiation immediately caused well-defined cortical coagulation necrosis. Within 5 minutes after unilateral irradiation, 14C-iodoantipyrine autoradiographs demonstrated severely reduced blood flow to the irradiation site and perilesional neocortex, but a distinct reactive hyperemia in all other areas of the forebrain. Apart from a persistent ischemic focus in the vicinity of the cortical coagulation necrosis, blood flow alterations in remote areas of the brain subsided within 3 hours after irradiation. Autoradiographic assessment of 3H-tyrosine incorporation into brain proteins revealed rapid onset and prolonged duration of protein synthesis inhibition in perifocal morphologically intact cortical and subcortical structures. Impairment of amino acid incorporation proved to be completely reversible within 48 hours. Immunoautoradiographic visualization of extravasated plasma proteins using 3H-labeled rabbit anti-rat immunoglobulins-showed that, up to 1 hour after irradiation, immunoreactive proteins were confined to the neocortex at the irradiation site. At 4 hours, vasogenic edema was present in the vicinity of the irradiation site and the subcortical white matter, and, at later stages (16 to 36 hours), also extended into the contralateral hemisphere. Although this was followed by a gradual decrease in labeling intensity, resolution of edema was still not complete after 48 hours. Analysis of sequential functional changes in conjunction with morphological alterations indicates that the evolution of morphological damage after laser irradiation does not correlate with the time course and spatial distribution of protein synthesis inhibition or vasogenic edema. Although the central coagulation necrosis represents a direct effect of radiation, the final size of the laser-induced lesion is determined by a delayed colliquation necrosis due to persistent perifocal ischemia. Extent and severity of ischemia in a zone with initial preservation of neuroglial cells can be explained by the optical properties of the Nd:YAG laser; extensive scattering of light within brain parenchyma associated with a high blood-to-brain absorption ratio selectively affects blood vessels outside the irradiation focus.

Hemangioblastomas of the central nervous system. A 10-year study with special reference to von Hippel-Lindau syndrome.

The findings of a 10-year study (1976 to 1986) conducted in southwest Germany on hemangioblastomas (HBL's) of the central nervous system (CNS) are presented. During that period, 47 HBL's were diagnosed and surgically removed in 44 patients, with a good postoperative survival rate and prognosis. The majority (83%) of these tumors were located in the cerebellum. By thorough clinical examination of the patients and careful evaluation of their family background, it was found that 23% of the HBL patients were afflicted with von Hippel-Lindau syndrome. In addition to the CNS tumors, 14 neoplastic or similar lesions were detected in other tissues. These included angiomatosis of the retinae, pheochromocytomas, pancreatic cysts, renal cysts, and renal carcinoma. The diagnosis of von Hippel-Lindau syndrome was thus established in seven families. The authors suggest the need for a screening program for patients with HBL of the CNS which is designed to confirm or exclude ocular or visceral lesions associated with von Hippel-Lindau syndrome.

Haemodynamic changes in arteriovenous malformations induced by superselective embolization: transcranial Doppler evaluation.

To reduce the intraoperative and postoperative complications in patients who suffer intracerebral arteriovenous malformations (AVM's), the slow reduction of the shunt flow to a brain perfusion flow has been tried by the use of several methods: microsurgical techniques, selective and superselective embolization, intraoperative embolization, staged operation. The risk of re-bleeding and intraoperative oedema increases in AVM's with two or more feeders. Our policy was to exclude such AVM's by primary superselective embolization. If there was only a small residual angioma, we tried to remove this by microsurgical techniques. The haemodynamics in AVM's could be examined by measuring the blood flow velocities in the feeding arteries and in the other parts of the circle of Willis by transcranial Doppler sonography (TCD). Signs of haemodynamic effective embolization could be measured by the reduction of flow velocities. After exclusion of an AVM the velocities in the brain and feeding arteries decreased to below normal values in the first days after the operation. In the feeding arteries this was due to the fact that the arteries were enlarged so that the velocity must be decreased when there was normal volume flow. The combination of superselective angiography and microsurgical resection of the residual angioma seemed to be the best way to treat AVM's which are fed by more than two arteries and which are 3 or more cm in diameter. TCD investigations were used to measure the haemodynamic changes before and after angioma superselective embolization and microsurgical operation.

Mesenchymal chondrosarcoma of the craniocervical junction.

Mesenchymal chondrosarcomas are found with equal low frequency in bone and soft tissue. The CNS is the most commonly reported site of extraosseous origin of mesenchymal chondrosarcomas. This report concerns the CT, MRI, and pathologic findings as well as the operative management of a mesenchymal chondrosarcoma of the craniocervical junction.

Intracranial chondroma. Case report.

We present a rare case of intracranial chondroma originating from the falx cerebri. Diagnostic procedures and surgical management are discussed, with special reference to computed tomography, magnetic resonance imaging, and pathologic findings.

[A rare form of open spinal cord injury]. / Eine seltene Form der offenen Rückenmarksverletzung.

By means of an injury of the spinal cord by a glass fragment in a 13-year old boy the problems of operative treatment of penetrating spinal cord wounds are represented. Provided that spinal computer tomography and microsurgical operative techniques are available, penetrating spinal cord injuries should be treated surgically after spinal cord edema has disappeared. By this means secondary infections, meningoceles, and adhesions of the spinal cord to the scar tissue can be prevented.

[On the lateral localisation of juxtamedullary tumours]. / Zur Seitenlokalisation juxtamedullärer Tumoren.

The significance of neurological deficit and radiological findings to the pre-operative determination of the relations of extramedullary tumours to the spinal cord was investigated in 37 patients with spinal neurinomas and meningiomas. On the basis of two simple methods a correct prediction of the affected side of the vertebral canal was possible in 92%. Myelographic findings indicated the correct localisation of the tumour in 65%. Among the neurological deficits the motor deficit indicated the correct side most frequently.

Clinical long-term results of anterior discectomy without fusion for treatment of cervical radiculopathy and myelopathy. A follow-up of 164 cases.

Between 1976 and 1983, 251 patients underwent surgery for the treatment of cervical degenerative disc disease. Anterior microsurgical discectomy at one or more cervical segments without interbody fusion was performed in each case. 109 patients with radiculopathy and 55 patients with myelopathy were followed up clinically 1 to 8 years postoperatively. A soft disc lesion was found in 72, a hard disc lesion in 92 patients. Of all radicular symptoms and signs, brachialgia and motor deficits of the upper extremities showed the highest improvement rates. The medullary complaints were improved in 80%, the progression of the disease was arrested in 93% of myelopathic cases. An excellent or good long-term result was achieved in 82% of patients with radiculopathy and 55% of those with myelopathy. The outcome was best in cases with soft disc lesions, with monosegmental disease, in individuals under 50 years of age, and in patients with a sudden onset and a short duration of symptoms. These results are comparable with those obtained by other surgical methods.

Extradural and intradural microsurgical approaches to lesions of the optic canal and the superior orbital fissure.

Within 3 years, 34 patients with lesions of the posterior part of the orbit, the optic canal, and the superior orbital fissure were operated using different surgical approaches. The results on the functional and cosmetic outcomes were compiled. The pterional approach was shown to be the most useful one. It can be used in intradural as well as in extradural and combined operations. It allows an excellent view of basal cerebral structures as well as the frontal base of the skull. The operative results are dependent on the type and the location of the lesion, and, especially in meningiomas, on their relationship to the cavernous sinus.

Transoral operations for craniospinal malformations.

The transoral approach to the lower third of the clivus and to the ventral aspect of the upper cervical spine is used in craniospinal malformations with or without dislocation as well as in basilar aneurysms, ventrally situated cranio-spinal tumours, fractures of the odontoid process, and in rheumatoid arthritis compressing the spinal cord. In consideration of the literature and ten personal cases the indications and techniques of the transoral approach in craniospinal malformations are discussed. According to our own experiences and those of other authors it is possible to expose the lower clivus and the cervical spine down to C2 by a midline incision of the pharyngeal wall using a mouth retractor and oral intubation. Splitting of the soft palate or resection of the hard palate are not necessary, a tracheotomy should be performed only in exceptional cases. In congenital craniospinal malformations without dislocation or instability causing a ventral compression of the spinal cord, for instance by the odontoid process, the transoral decompression is preferable to dorsal decompressing operations. In cases of pure instability without any space-occupying lesion the transoral and posterior approach are possible in order to perform a fusion. The last one seems more advantageous in these cases. In craniospinal malformations with dislocation causing a ventral and dorsal narrowing of the spinal canal, apart from the decompression a stabilization has to be achieved. In these usually complex malformations individual treatment is necessary. According to the rare cases in the literature and to our own experience a primary anterior decompression, followed by a most careful posterior stabilization seems to produce the most favourable results.

[Microsurgery of sphenoidal ridge meningiomas (author's transl)]. / Zur Mikrochirurgie der Keilbeinflügelmeningeome.

On the basis of 22 sphenoidal ridge meningiomas operated on in the last two years, the topographical relationship of these tumours to the brain and the base of the skull is described. The microsurgical technique which is used is described and its advantages discussed.

[Motor rhythms synchronous with respiration in the decerebration syndrome of man]. / Uber atmungssynchrone motorische Rhythmen beim Decerebrationssyndrom des Menschen.

Rhythmical somatomotor discharges in the EMG from arms and legs are recorded together with the respiration in decerebrated patients. The rhythms of 7-18/min are synchronous with respiration. The slow activations of 0.3-0.8/min are related to periods of acceleration with higher amplitudes of respiration. The quick rhythms above 2/min correlate with single respiratory movements. They are interpreted as a phenomenon of disinhibition of lower brain stem structures.

Complications of anterior cervical discectomy without fusion in 450 consecutive patients.

The complications of anterior discectomy without fusion were analyzed on the basis of 450 consecutive cases treated surgically for degenerative disc disease. There was no death related to the procedure. The most common complication was a worsening of the pre-existing myelopathy. This occurred in 3.3%, including one case with severe medullary contusion. Wound infection developed in 1.6%. Additional radicular symptoms and wound haematoma, respectively, occurred in 1.3%; recurrent nerve palsy, Horner's syndrome, and respiratory insufficiency, respectively, in 1.1% of the cases. Epidural haematoma and instability of the cervical spine, respectively, occurred in 0.9%, nerve root lesion and aseptic spondylodiscitis, respectively, in 0.4%. There was one case each (0.2%) with a pharyngeal lesion, meningitis due to dural perforation, transient additional myelopathy, and epidural abscess. The results and the management of complications are discussed in relation to numerous previously published reports, including posterior procedures and anterior fusion techniques. Precise knowledge of all potential accidents and pitfalls related to the surgical procedure and of their aetiology may contribute to preventing failures. The rate of complications in this series has been reduced in the past years by better patient selection, by paying more attention to correct positioning of the patient during the operation, and by meticulous removal of all offending structures. Discectomy without interbody fusion is now considered to be a reasonably safe procedure with an acceptable operative morbidity and lack of mortality.

[Recurrence following burr hole trephination of chronic subdural hematomas]. / Rezidive nach Bohrlochtrepanation chronischer Subduralhämatome.

In a consecutive series of 100 patients suffering from Chronic subdural haematomas, which were treated by burr-hole evacuation and closed external drainage, in 23 patients repeated operations became necessary. The reasons for further operations were: true recurrences in 11 cases, superimposed haematomas in five cases and haematomas on the opposite side in seven cases. All these patients were treated again by burr-hole evacuation and closed external drainage. In contrast to the common opinion craniotomy and removal of the membranes was not necessary in any case.

Cavernous angiomas of the skull.

The authors present a series of 25 cases of haemangioma of the skull and review the literature. Frontal localization was the most frequent, contrary to the data in the literature which suggest predominance in the parietal region. The reported predominance of females has not been confirmed. In the present series the relation of males to females was 17:8. The radiological findings and treatment of haemangiomas are discussed. Direct puncture and injection of contrast medium is the best method of visualization of the tumour. Treatment should be surgical, consisting of total extirpation of the tumour with a margin of healthy tissue. Simple extirpation is indicated only when the soft tissues are involved and there is no bone lesion. Excision en bloc is the tehcnique of choice.

Possibilities and limits of the midline interhemispheric approach.

Based on experience in 17 children operated upon between 1978 and 1984, the possibilities and limitations of the interhemispheric parafalx approach to lesions of the anterior and posterior lateral ventricles and the third ventricle are described. The interhemispheric approach seems more advantageous than transcortical approaches since additional cortical and white matter lesions can be avoided. The limitations of visibility are the same as in transcortical approaches.

Unilateral microsurgical approaches to extramedullary spinal tumours. Operative technique and results.

The operative technique of limited approaches to extramedullary spinal tumours is described. The results after unilateral approaches are as satisfying as after standard laminectomies. The rationale of attempting an unilateral approach is to avoid damage to the dorsal static structures of the vertebral column. Access given by limited approach and possibilities of enlarging the bony defect depending on the topographical situation of the tumour are discussed in detail. It is emphasized that the dura should be opened only over the tumour in order to avoid protrusion of the cord.