Use of multimodal electrophysiological monitoring to predict outcome after subarachnoid hemorrhage? A prospective series.

AIM: Electrophysiological monitoring (EM) is still controversial in the prediction of outcome after subarachnoid hemorrhage (SAH). The absence of evoked potentials (EP) is a good predictor for unfavorable, whereas the prediction of favorable outcome may be less useful. Aim of this study was to evaluate, if multimodal EM provides significant information about the patients' outcome or if this method might be dispensable. METHODS: Multimodal EP data were recorded sequentially in 51 SAH-patients. The following data were recorded: World Federation of Neurological Surgeons (WFNS-) grade, Fisher grading score, endovascular versus neurosurgical treatment, aneurysm location and clinical outcome according to the Glasgow Outcome Scale (GOS). Multimodal electrophysiological monitoring included median nerve somatosensory evoked potential (M-SSEP), tibial nerve somatosensory evoked potential (T-SSEP), flash-visual evoked potential (f-VEP), brainstem auditory evoked potential (BAEP) and central conduction time (CCT) of M-SSEP. EP data were recorded sequentially; the first and last studies were evaluated. RESULTS: No correlation was found between initial and last M-SSEP, T-SSEP, BAEP and initial f-VEP and the patients' outcome. An 'unfavorable' outcome was in conjunction with an initial delayed CCT (>6 ms, P=0.03) and the final f-VEP correlated well with the patients' outcome (P=0.03). CONCLUSION: In conclusion, neither T-SSEP, f-VEP, BAEP nor CCT can be used as valid predictor for outcome after SAH. The patient's initial clinical grading still provides the only satisfying predictor, independent of the patient's clinical course.

The prognostic value of somatosensory evoked potentials in traumatic primary and secondary brain stem lesions.

To estimate the prognostic value of somatosensory evoked potentials elicited via stimulation of the median nerve (M-SSEP) in cases of primary and secondary brainstem lesions 126 patients with traumatic brainstem lesions (GCS < or = 6) were investigated on admission to our hospital. Various parameters of the patients' M-SSEP were compared with the corresponding data of 40 healthy persons. Latency and amplitude of the cervical (N14) and cortical (N20) derived potentials and the central conduction time (CCT) were taken into account. Changes or a loss of the N20 signal and of the CCT were related to clinical outcome for up to two years. All patients had a normal N14 bilaterally. Most patients with a primary brainstem lesion (n = 25) showed symmetrical N20 changes bilaterally. However, the majority of patients with a secondary brainstem lesion (n = 62) showed asymmetric N20 changes in M-SSEP which became more symmetrical in cases with marked progressive brainstem compression. Irrespective of a primary or secondary traumatic brainstem lesion, marked changes of N20 represented an unfavourable clinical prognosis. A loss of N20 was closely correlated with a very poor outcome (GOS 1-2) if the N20 potential had not recovered within 48 hours. The recovery of this potential, however, was not necessarily correlated to a recovery of the brain function.

Surgical correction of scaphocephaly: experiences with a new procedure and follow-up investigations.

INTRODUCTION: Simple resection of the sagittal suture and the use of alloplastic material or extensive skull resections have long been proven to be unsatisfactory in the treatment of sagittal synostosis. In contrast to these experiences, the immediate correction of skull shape seems to yield the best results without significant morbidity. PATIENTS: Thirty-six scaphocephalic infants with an average age of 6.5 (3.5-14) months underwent operation by our craniofacial team since 1994. METHODS: Wide resection of the sagittal suture was used in combination with a bone-strip resection along the coronal and lambdoid sutures. Occasionally partial resection and reshaping of the frontal or occipital bone was necessary to correct an extremely bulging skull. The cranial growth and shape was monitored by anthropometric skull measurements in the last 20 patients. RESULTS: Except in two cases, in which the dura mater was minimally injured intraoperatively, no complications occurred in any patient. Craniofacial oedema always occurred but disappeared after 72 h. The immediate correction of the skull shape was successful in all cases and was completed within 6 months postoperatively. There was no iatrogenic bone defect one year after surgery. Postoperative skull shape and growth was normal. CONCLUSION: These procedures seem to be effective in the treatment of scaphocephalus. Further normalization of skull shape is achieved by unrestricted postoperative brain growth.

Somatosensory evoked potential monitoring during positioning of the patient for posterior fossa surgery in the semisitting position.

OBJECTIVE: Midcervical flexion myelopathy is a rare but well-known complication of posterior fossa surgery. To reduce the risk, we routinely used somatosensory evoked potential (SSEP) monitoring during positioning of the patient. METHODS: Fifty-five consecutive patients were operated on for posterior fossa lesions in the semisitting position via a median (5 patients) or a lateral (50 patients) suboccipital approach. During positioning, monitoring of SSEPs by stimulation of the tibial nerve (T-SSEP) as well as by stimulation of the median nerve (M-SSEP) was established. In the case of pronounced SSEP changes, the head was repositioned. Surgery was started after SSEP recordings were unchanged as compared to the baseline investigation. RESULTS: Effective monitoring was possible in all cases. Whereas M-SSEP recordings showed no changes while placing patients in the sitting position, T-SSEP recordings were altered in 14 cases (25%). In cases using the midline approach, SSEP changes were never so pronounced to require repositioning of the head. Head flexion and rotation resulted in significant changes of T-SSEP recordings in eight patients (14.5%), requiring repositioning. In two cases, an amplitude loss was noted. In only two of these eight patients were M-SSEP recordings markedly changed. SSEP recordings after repositioning disclosed recovery of spinal cord function. In no patient were clinical signs of myelopathy observed postoperatively. CONCLUSION: We observed a high incidence of pronounced changes of T-SSEP recordings when the patient's head was flexed and rotated for lateral suboccipital craniotomy in the semisitting position. Despite the low specificity monitoring of T-SSEPs during positioning of the patient for posterior fossa surgery, the semisitting position is strongly recommended.

[Visual evoked potentials as an indicator of supratentorial and infratentorial herniation]. / VEP als Indikator der transtentoriellen Herniation bei supra- und infratentoriellen Raumforderungen.

The VEP was investigated in 172 patients with infratentorial and in 100 patients with supratentorial space occupying lesions. In each group 65% of the patients showed marked or even extensive changes in VEP. An immediate relation of the lesion to the optochiasmatic system or a hydrocephalus was noted in a few cases only. In contrast the VEP of patients with a clear transtentorial herniation showed severely pathological changes, occasionally up to complete loss of the potential. The VEP changes were reversible on removal of the space occupying lesions in all patients. The constellation of VEP changes in subgroups of patients with different types of the space occupying lesions, as well as the observed symmetry of the VEP changes, allow the assumption that the functional inhibition of the optic pathway occurs in the perimesencephalic part via their compression or stretching. The assumption is supported by pathoanatomical MRT findings in some cases. It seems, therefore, that VEP investigations enable the registration of a compression or torsion of the cranial mesencephalon (mesencephalo-diencephalic mechanical irritation) or the presence of a clinical silent transtentorial herniation in space occupying lesions. The loss of the VEP appears to yield an early and certain signal of the progressing mid-brain syndrome.

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.

[Metaplastic ossification in an acoustic neurinoma]. / Metaplastische Ossifikation in einem Akustikusneurinom.

We report the case of a 52-year-old woman with a cerebellopontine angle tumor, which appeared to have arisen from the 8th nerve. Microscopically the tumor was proved to be an acoustic neurinoma and showed unusual findings such as inclusions of mature bone and bone marrow. The histogenesis and diagnostic relevance of the very rare heterotopic osteogenesis in acoustic neurinomas is discussed.

Temperature regulation as possible prognostic indicator in patients with acute intracranial lesions.

24 patients, 16 after severe head injury and 8 after spontaneous intracranial haematoma, were investigated by external cold load in order to determine their thermoregulatory capabilities. Tympanic temperature, several skin temperatures and oxygen consumption were measured. The patients where examined for SSEP and AEP. The cold induced thermoregulatory threshold temperature was determined by calculating the mean body temperature and by determining mean body temperature at which oxygen consumption increased due to the external cold load. In all patients core temperature and mean body temperature were significantly elevated by 1 degree C compared to controls. There was no difference of the course of the various body temperatures during cold load in the patient groups. In the trauma group 8 patients were able to increase oxygen use (VO2) during cold exposure, the other 8 patients showed no physiological thermoregulatory reaction. The heatproduction threshold temperature was increased by 1 degree C in the patient groups compared to controls. There was no significant correlation of AEP and SSEP findings to a preserved or disturbed thermoregulatory reaction. In the trauma patients, who were able to respond to a cold load, the outcome was significantly better (GOS = 3-5), than in those patients, who did not show a physiological increase of VO2 due to the cold load (GOS = 1-2). In conclusion, measurement of body temperatures alone is not sufficient to determine termoregulatory capacities. An examination using thermophysiological methods however provides more information about the function and structure damaged after severe head injury. An intact thermoregulatory systems seems to be correlated with a better prognosis after head injury.

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.

[Changes in visually evoked potentials in space-occupying processes of the posterior fossa--on the problem of ascending transtentorial herniation]. / Veränderungen der visuell evozierten Potentiale bei raumfordernden Prozessen der hinteren Schädelgrube--Zum Problem der aszendierenden transtentoriellen Herniation.

Through the use of VEP investigations in 82 patients with space occupying lesions in the infratentorial region this study attempts to find the cause and location of dysfunctions of optical signal pathways. The majority of such expandatory processes involved tumours exterior to the brainstem of inhomogeneous histomorphology (n = 65). The rest involved metastases of the cerebellum (n = 5) and expanding infarcts of one cerebellar hemisphere (n = 12). Besides a shifting of the 4th ventricle (n = 64) an accompanying hydrocephalus (n = 40) and an ascending transtentorial herniation (n = 29) was indicated radiologically. A pathological VEP was found in just over half of the patients (n = 43). Usually, the VEP change involved a latency increase of the cortical potential (P2). In 6 of these patients a complete loss of this potential was noted. Furthermore, ten more of these patients did not have the P1-following negative potential (N2). In 32 patients with a pathological VEP a hydrocephalus was proven to be present. On the other hand, there were 8 patients with accompanying hydrocephalus but with a normal VEP. All 29 patients, though, with a radiological ascending herniation had changed VEP. Three of these patients had no accompanying hydrocephalus. Following surgical decompression a complete normalization of the VEP set within 2 to 3 weeks, while it reappeared in tumour recurrence. These findings indicate that dysfunctions of VEP, that is the visual pathways in infratentorial occupying lesions are not only dependent on the existence of accompanying hydrocephalus.(ABSTRACT TRUNCATED AT 250 WORDS)

[Functional studies of the spinal cord in chronic stenosing diseases of the cervical spine using somatosensory evoked potentials]. / Funktionsuntersuchungen des Myelons bei chronischen stenosierenden Erkrankungen der Halswirbelsäule mit Hilfe von somatosensorisch evozierter Potentiale.

Report about 35 persons with chronic stenosing diseases of cervical spine which was investigated through somatosensory evoked potentials (SSEP) after stimulation of the median (M-SSEP), ulnar (U-SSEP) and tibial (T-SSEP) nerve. The examinations were always performed in extreme possible cervical ante and retroflexion. The majority of patients (n = 17) presented with a bony spinal stenosis. Less often were cervical disc prolaps (n = 8) or a atlanto-axial dislocation in primary chronic polyarthritis (n = 7) the cause of the illness. The rest of the patients (n = 3) had still different sources of stenoses of the spine. In 23 of 35 patients a change of the SSEP occurred during measurement while in this extreme cervical ante-and retroflexion. In 15 of these cases the initially pathological SSEP deteriorated, while in 8 patients an initially normal SSEP turned pathological in the functional position. Most often changes of the so-called "Functional SSEP" occurred in multisegmental bony cervical stenosis. In most cases a change in the T-SSEP obtained, independently of the main localisation of the radiologically verified spinal stenosis. The SSEP changes are illustrated through typical examples. The determination of SSEP in extreme positions of the cervical spine appears, therefore, as a suitable method to discover transient dysfunctions or the increase of dysfunctions of the cervical spinal cord. They can also serve as a preoperative screening method of dysfunctions of the cervical spinal cord in operations of planned long duration with unfavourable positioning of the cervical spine (extreme antiflexion, twisting, or retroflexion).(ABSTRACT TRUNCATED AT 250 WORDS)

Rhinorrhea following dopamine agonist therapy of invasive macroprolactinoma.

We report on the occurrence of CSF rhinorrhea in a group of 17 patients harbouring macroprolactinomas who were treated with a dopamine agonist (DA, bromocriptine) alone or the combination of DA and transcranial operation. In 2 out of 17 cases shrinkage of tumour remnants during therapy with the oral or injectable form of bromocriptine was responsible for delayed occurrence of rhinorrhea. Operative procedures for successful closure of the fistulae were mandatory in both cases.

[Giant cell tumors, aneurysmal bone cysts and osteoid osteomas of the spine]. / Riesenzelltumoren, aneurysmatische Knochenzysten und Osteoide osteome der Wirbelsäule.

Experience collected by us from treating 15 patients suffering from giant cell tumours, aneurysmatic bone cysts or an osteoid osteoma prompted us to investigate which progress has been made to date in the diagnosis and treatment of these lesions that contain giant cells, basing on recent diagnostic methods such as computed tomography and magnetic resonance, as well as neurosurgical methods. It was found that the course of these rare changes cannot be influenced either by extensive diagnostic or special neurosurgical measures and that the prognosis finally depends on the growth trends inherent in the lesion concerned. Now that both diagnostic and surgical techniques are more refined than previously, there is a tendency to an improved individual approach that is better suited to the needs of the patient. Radiotherapy of benign changes involving giant cells in the region of the vertebral column is no longer of any importance.

[Intraoperative monitoring with visual and auditory evoked potentials]. / Intraoperatives Monitoring mit visuellen und akustisch evozierten Potentialen.

Intraoperative monitoring techniques concerning evoked potentials have been used during operations on the spinal cord as well as in carotid endarterectomy and in aneurysm surgery. The monitoring of early acoustic evoked potentials during surgery of the posterior fossa and the registration of the visually evoked potentials in patients suffering from pituitary adenoma or other space occupying lesions of the sella region seem to provide information about function of nerves and brain stem structures. This paper deals with positive and negative aspects of intraoperative monitoring of visual and acoustic evoked potentials.