Timing of operation for ruptured cerebral aneurysm and long-term recovery of cognitive functions.

Advantage and disadvantages of early and late operation for ruptured cerebral aneurysm are controversially evaluated with regard to peri-operative operation outcome and long-term cognitive recovery. In this retrospective analysis 22 patients with early surgery (ES) within three days after subarachnoid haemorrhage (SAH) and 22 patients with late surgery (LS) at least 14 days after SAH were studied. Patients were pair-wise matched by degree of SAH localisation of aneurysm and age at SAH. On average three years after SAH both groups were examined individually with a comprehensive neuropsychological test battery including tests of premorbid intelligence, concept formation, memory, visuomotor speed, aphasia screening, and mood. ES and LS patients were well comparable in terms of years of education and level of premorbid intelligence. There was a clear influence of patients age on fluid intelligence tests, indicating a general change-sensitivity of tests. No influence of degree of SAH and localisation of aneurysm could be detected. There were also no differences between ES and LS patients in neuropsychological tests sensitive to brain damage, suggesting that the decision for early or late surgery for ruptured cerebral aneurysm can be based upon surgical reasons at the time of the SAH.

Surgical treatment and results in patients suffering from lumbar spinal stenoses.

Stenosis of the lumbar spinal canal is contributing to 3-5% of all patients operated on a lumbar nerve root compression syndrome. Morphologically, a reduction of the midsagittal diameter of the spinal canal to less than 12 mm or stenoses of the lateral recessus or foramen intervertebrale have been described. In our department 37 patients with a lumbar spinal stenosis have been surgically treated between 1982 and 1987. Spinal stenosis is a disease of aged patients mostly suffering for a long history. The main symptoms are lumbar and sciatic pains, neurological deficits and a claudicatio intermittens spinalis. Neuroradiologically, the diagnosis can be confirmed by CT, myelography or MRI. These studies were demonstrating the stenosis in 69% at the level of L4/5, multiple stenoses have been found in 22% of all cases. An additional disc herniation existed in 35% of the patients. Concerning the specific complaints of the patients and their neuroradiological findings, the extent of the surgical decompression was decided on individually in each patient. We performed 22 laminectomies, 11 hemilaminectomies, in 3 cases an extended flavectomy and in one case an implantation of a dorsal column stimulation device. The postoperative follow-up period, ranging from 3 months to 3 years, demonstrated a complete recovery in 53%, a marked reduction of complaints in 44% of all cases. One patient did not respond to surgical treatment, but in the remaining cases surgical treatment led to satisfactory results.

Fourier analysis of the cerebrovascular system.

We performed Fourier analysis of the middle cerebral artery blood flow velocity waveform envelope in 14 normal subjects (group A) and 15 patients, of whom five had arteriovenous malformations (group B), five had cerebral vasospasm (group C), and five had arterial hypertension (group D). Measurements were obtained under conditions of normocapnia, hypercapnia, and hypocapnia. The Fourier coefficients measured in the first five harmonics of the Doppler waveforms of group A were used as the reference baseline and were compared with the coefficients found in the other three groups. Group B showed significantly lower Fourier coefficients, while groups C and D showed higher coefficients (p less than 0.05). The elevation of the Fourier coefficients occurred in an alternating pattern in group C and a decremental pattern in group D. This distinction was attributed to possible differences in the underlying pathophysiological processes. The degree of vascular distensibility of the cerebral arterioles, inferred from the shape of the Fourier analysis curves, was compared in all four groups. Vascular distensibility was characterized as abnormal in arteriovenous malformations, vasospasm, and arterial hypertension. Fourier coefficients may be better indicators of cerebrovascular abnormalities than mean blood flow velocity in hypertension and pulsatility index in arteriovenous malformations, vasospasm, and hypertension.

Nd:YAG-laser in the microsurgery of frontobasal meningiomas.

Forty-three patients with big frontobasal meningiomas underwent a microsurgical removal of the tumor. The 1.32 microns Nd:YAG-laser has proved useful in this prospective series particularly with the contactless shrinkage of the tumors and the necrotization of the dural and bony attachments. Tumor shrinkage was achieved by radiating the tumor surface with the Nd:YAG-laser. This technique facilitated the microsurgical dissection and reduced the blood loss by half. The Nd:YAG-laser necrotization of the dural and bony attachments reduced the recurrence rate following grade two resections from 20% to zero. The postoperative quality of life was excellent with a complete rehabilitation in 76% of the patients. The use of the 1.32 microns Nd:YAG-laser improved significantly the results of microsurgery for frontobasal meningioma.

Surgical treatment of patients with midline arachnoid cysts.

Usually, arachnoid cysts are found in the Sylvian fissure (about 85%); midline arachnoid cysts are rare. Typical clinical symptoms are increased intracranial pressure, caused by a concomitant hydrocephalus, as well as visual and/or endocrinological disturbances. Six patients were examined, treated with one of two different surgical methods (cyst shunting or open treatment, either craniotomy/cyst membrane resection or laser endoscopy). Better results were observed following open treatment methods.

MR-gated intracranial CSF dynamics: evaluation of CSF pulsatile flow.

This article describes a new imaging method, called MR-gated intracranial CSF (liquor) dynamics, or MR-GILD. Pulsatile flow in CSF pathways is revealed by the difference between diastolic- and systolic-gated images. The images clearly demonstrate the ventricles, cisterns, and vascular structures. The dependence of CSF movement on arterial pulse transformation is analyzed, illustrative cases are given to show some pathologic variations, and the use of MR-GILD for neurosurgical patients is discussed.

Comparative investigations of the effects of the neodymium:YAG laser at 1.06 microns and 1.32 microns on tissue.

The beneficial deep homogeneous coagulation of neodymium (Nd):YAG laser radiation at 1.06 microns owing to low absorption and high scattering in tissue has been documented widely. For another Nd:YAG laser wavelength at 1.32 microns the absorption coefficient of water and saline is approximately ten times higher than at 1.06 microns. This results in more efficient energy conversion into heat in tissue at 1.32 microns. The extinction coefficient in blood at 1.32 microns is only one-third of that at 1.06 microns. We would expect this to result in less heat dissipation by blood and deeper penetration in tissue at 1.32 microns. Nevertheless, at this wavelength scattering also contributes to an effective, uniform distribution of the laser light in the tissue. Animal experiments have been done to examine the effect of wavelength, irradiation time, and beam geometry on tissue damage and to assess its possible clinical uses. The results imply that the 1.32 microns wavelength will produce further indications for the use of the Nd:YAG laser in surgery.

The use of the Nd-YAG laser in neurosurgery.

Whereas the focused CO2 laser may be used as a cutting instrument in less vascularized tissue with limited trauma to the surrounding tissue, use of the defocused Nd-YAG laser results in homogeneous coagulation with an energy-dependent depth effect. Thus, residual tumor tissue may be cauterized selectively with a depth effect which can be predicted with satisfactory precision. Tumor shrinkage and demarcation based on different absorption properties facilitates dissection and, moreover, allows the preservation of healthy tissue. The excellent coagulating properties of the Nd-YAG laser render it especially effective in cases of highly vascularized meningeal tumors.

[Experiences with the Nd-YAG laser in the surgical treatment of intra- and suprasellar tumors]. / Erfahrungen mit dem Nd-YAG-Laser in der chirurgischen behandlung intra- und suprasellärer Tumoren.

The Neodym-YAG-laser has been used in 15 transcranial and 15 transsphenoidal operations of intra- und suprasellar tumors. The surgical results are reflected by ophthalmological and endocrinological controls. The incidence and nature of surgical complications is also reported. The practical experiences during the surgical procedure as well as the results are indicating, that the Nd-YAG-laser is superior to conventional surgical methods. In addition to a better control of bleeding, laser surgery allows a more radical removal and inactivation of tumor tissue without a higher risk of lesioning the adjacent structures.

Use of the Nd-YAG laser in neurosurgery.

After many years of experience, in general we prefer the Nd-YAG laser, although the CO2 laser is an advantage in a few specific cases (lipomas, cranial synostosis). While the focused CO2 laser may be used as a cutting instrument in less vascular tissue with little trauma to the surroundings, the Nd-YAG laser produces a homogeneous coagulation with an energy dependent depth effect. Thus, with the Nd-YAG laser residual tumour tissue can be selectively and with a predictable depth effect thermally destroyed. Because of its excellent coagulation property, the use of the Nd-YAG laser is particularly indicated in highly vascular meningeal tumours. The shrinkage of a tumour and its demarcation which is due to the varying absorption properties facilitates the dissection and allows in addition the preservation of normal tissue.

[Use of the Nd-YAG laser in the treatment of tumors in the area of the craniocervical transition]. / Die Anwendung des Nd-YAG-Lasers bei der Behandlung von Tumoren im Bereich des kraniozervikalen Ubergangs.

The primary symptom in patients with tumors in the region of the foramen magnum is persistent neck pain. With the use of microneurosurgical techniques and additional laser therapy, favorable operative results can be obtained. The same holds true for patients harboring difficult to approach lesions such as ventrally located tumors of the craniocervical junction or with brain stem tumors. The advantages of the Nd-Yag-laser therapy are: precise denaturation of tumor tissue with predictable depth effect; adequate delineation of tumors due to different tissue absorption properties; excellent coagulation in the presence of highly vascularized tumors; surgery markedly facilitated due to laser induced shrinkage of tumors.

[Early diagnosis and treatment of aneurysmal hemorrhages (author's transl)]. / Frühdiagnose und Therapie der Aneurysma-blutungen.

The diagnostic and therapeutic procedures after aneurysmal hemorrhage are described. The most important aspects in history-taking, indication for lumbar puncture, the evaluation of computer tomographic findings and the method of angiography are presented and in particular the timely coordination of the preoperative measures and the operation is commented on.

The use of the Nd-YAG and the CO2 laser in neurosurgery.

Over the last 3 years 130 patients have been operated on using laser techniques. This technique was chosen where technical difficulties were anticipated due to the size, the vascular supply or the localization of the process. Although the use of laser techniques requires experimental work, before it can be applied clinically some distinct advantages could be demonstrated when compared with the use of the bipolar cautery. Due to its shrinking effect the laser beam is target oriented and makes the surgical procedure safe without the use of additional instruments. The Nd-YAG laser was preferred in tumors with a rich vascular supply. Thus there was a definitely decreased need for blood transfusions in patients operated on with the laser. Even those parts of the tumors that can not easily be reached, using conventional techniques can now be eliminated by laser irradiation. The variable distance between the handpiece of the laser instrument and the target organ allows a pin point as well as a more diffuse irradiation. Since it is not necessary to touch the tissue, laser techniques are particularly useful in critical areas, e.g. close to the brainstem or the spinal cord, because they make it unnecessary to touch the tissue. The question as to whether the use of laser technique will reduce the rate of recurrent tumor growth needs further studies based on longer follow-up periods. Further technical improvements are needed to make the laser device a true microinstrument. Finally a combination of both laser types--that is the Nd-YAG laser for coagulation and the CO2 laser for cutting--might be a definite advantage.