Spinal extradural arachnoid cyst causing cord compression in a 15-year-old girl: a case report.

The authors describe the case of a fifteen-year-old girl with progressive paraparesis of the lower limbs that was caused by an intraspinal extradural dorsal arachnoid cyst at the level of Th 3-6. Diagnosis was established with MRI and MRI myelography. The latter revealed the CSF-like content of the cyst. The patient underwent laminotomy and en bloc resection of the cyst. Ligation of the pedicle of the cyst was done with laminoplasty. Quick and complete recovery was observed after surgery.

Anteposition of the internal carotid artery for surgical treatment of kinking.

BACKGROUND: Kinking of the extracranial portion of the internal carotid artery (ICA) requires surgical reconstruction when it causes neurological symptoms. We suggest a simple surgical reconstruction without arteriotomy. METHOD: Anteposition of the ICA ventral to the digastric muscle has been performed in three patients. Kinks in the ICAs, proved by angiography, were thought to be responsible for clinical signs and symptoms. RESULTS: The operations resulted in improvement, both clinically and radiologically. CONCLUSION: The complications of arteriotomy can be avoided using the technique of ICA antepositioning described in this paper.

Posterior interbody fusion using laminectomy bone and transpedicular screw fixation in the treatment of lumbar spondylolisthesis.

BACKGROUND: Laminectomy bone is used widely in posterolateral lumbar fusion, but not interbody fusion. No prospective evaluation of interbody fusion using bone grafts from the posterior neural arch in spondylolisthesis has been found in the literature. We prospectively studied series of patients operated on for lumbar spondylolisthesis to evaluate clinical improvement and bony fusion. METHODS: Forty-six patients were operated on for lumbar spondylolisthesis using a simplified one-stage posterior procedure. The whole mobile dorsal segment of the vertebral arch was taken out in one piece and the bone was used for interbody fusion. Fixation was performed with transpedicular screws and rods using transverse connectors. RESULTS: After an average follow-up time of 27.3 months, 87% of the patients could be considered to have an excellent or good clinical outcome. The rate of successful fusion was 95.7%. No noteworthy complications occurred. CONCLUSION: Laminectomy bone seems to be optimal for posterior interbody fusion and together with transpedicular rigid fixation the long-term clinical and radiological results are convincingly good. The method is advisable even for severe spondylolisthesis.

Somatosensory and motor evoked potentials in patients with tumours in the spinal canal.

Motor and sensory evoked potentials were recorded in 27 patients with expanding spinal tumour. The patients were divided into 2 groups: I. tumours at the level of the spinal cord and II. at the level of the cauda equina. On the basis of the localization of the tumour, midline and lateral subgroups were distinguished. The latencies of motor evoked potentials were prolonged in most of the patients, even those without paresis, in both groups. The motor evoked potentials detected subclinical motor lesions in 7 patients. All patients but one manifested sensory deficits, which could not be shown with the somatosensory evoked potentials. Significantly more prolonged cortical motor latencies were found in most of the patients with a laterally located tumour on the tumour side than contralaterally, whereas in somatosensory evoked potentials this difference was not apparent. On the basis of these observations, we concluded that motor evoked potentials, 1. could more reliably detect the neural deficit than somatosensory evoked potentials; 2. could show the side where the tumour was located; 3. proved useful in the detection of subclinical motor lesions. The general conclusion may be drawn that this electrophysiological method can provide useful information for the surgeon.

Transtracheal electrical stimulation of the spinal cord for intraoperative monitoring of the motor pathway.

Because of the suppressant effects of anesthetic drugs and muscle relaxants on motor responses elicited by either magnetic or electrical transcranial stimulation, intraoperative monitoring of the motor system, and especially monitoring of lower limb function, presents many difficulties. The upper part of the spinal cord was stimulated in 14 anesthetized and relaxed dogs with a cathode attached to the intratracheal tube and an anode fixed above the upper cervical spinous processes. Action potentials evoked by single and serial stimuli were recorded from the exposed right femoral nerve and quadriceps muscle Averaging was necessary for serial stimulations. Reproducible early and late responses to both single and serial stimulations were recorded during regular anesthesia. The origin of the different responses is discussed. Transtracheal stimulation of the spinal cord is easy to perform and the responses recorded from the peripheral nerve or limb muscle are well reproducible in regular anesthesia. The method seems to be appropriate for intraoperative monitoring of the thoracolumbar spine.

Multimodal electrophysiological examinations in patients suffering from various tumors of the pineal region.

Multimodal electrophysiological examinations: blink-, glabella- and masseter-reflexes, as well as brain stem acoustic, somatosensory and visual evoked potentials were examined in thirteen patients with clear consciousness suffering from extra-axial, chronic, expanding processes in the tectal region. According to the data, the authors came to the conclusion that several modalities were often required to make a correct diagnosis or to the localization of the space occupying processes. Functional disturbances of the whole of the lower brain stem, but especially of the mesencephalon and of the lower pons were found in cases of expanding processes surrounding the tectum.

Intraoperative monitoring of the motor pathway using transtracheal stimulation of the cervical spine in dogs.

Although SEP monitoring of the spinal cord has been a well established method recently, not an ultimate, perfectly developed technique for monitoring of the motor system is known so far, particularly, because of the disturbing effect of narcotic drugs and relaxants on the motor evoked potentials. In this study the upper part of the spinal cord was stimulated in 14 anesthetized and relaxed dogs with a cathode attached to the intratracheal tube and an anode fixed to the cervical spinous processes. Single and serial stimuli were applied. Recordings were obtained from the exposed right femoral nerve and quadriceps muscle. Averaging was necessary when using serial stimulations. Responses were consequent and reproducible during regular anesthesia. The origin of the different responses in the spinal cord is discussed. The method seems to be appropriate for intraoperative monitoring of the thoracolumbar spine.

Motor and somatosensory conduction time between the cortex and the Erb point in patients suffering from cervical spinal stenosis and tumour.

Motor and sensory conduction time between the cortex and the Erb point were examined in patients with cervical cord compression. Patients were divided into two groups: the compression was caused either by cervical extramedullary tumour (9 cases), or by cervical spondylosis or herniated disc (16 cases). In response to median nerve stimulation, pathological somatosensory evoked potentials were recorded in 66% of the patients suffering from tumour and in 60% of the patients suffering from spondylosis. All of the patients disclosed pathological motor evoked potentials. On the basis of these observations it could be concluded that, in cases of cervical spinal cord compression, the involvement of the motor system could be more reliably detected than that of the sensory system with electrophysiological methods.

The acoustic evoked brainstem potential of the cat. An experimental study.

In 15 cats, the brainstem auditory evoked potentials were registered in far-field and near-field technique after surgical exposure of the rhomboid fossa. By alterations of the stimulus side and change in position of the registration electrodes on the one hand as well as by tract severance on the other hand, some interesting findings could be obtained never published before. Our investigations indicate that the far-field potentials registered from the scalp are generated axonally and constitute summation potentials of several generators. Accordingly, one should not refer to individual generators with regard to the scalp potentials, but rather to brainstem segments in which the individual potentials are generated.

Multimodality electroneurophysiological findings in intra-axial and extra-axial lesions of the brain stem.

In 330 patients with a space occupying lesion of the posterior cranial fossa, the blink (BR) and masseter (MR) reflexes and brain stem auditory (BAEP) and somatosensory evoked potentials (SEP) were registered. The aim of our study was to look for electrophysiological criteria of differentiating between lesions within or outside the brain stem. The ipsilateral loss of BAEP in cerebellopontine angle tumours and the altered SEP in tumours within the brain stem turned out as frequent, almost specific findings. Prolonged ipsi-and contralateral late BR responses and prolonged MR responses, a long somatosensory central conduction time of the SEP and a prolonged wave III latency as well as a prolonged interpeak latency of the BAEP are not indicative but highly suspicious for a lesion within the brain stem. Prolonged early responses of the BR together with prolonged interpeak latencies of the BAEP are characteristic findings in cerebello-pontine angle tumours.