Blunted serum and enhanced salivary free cortisol concentrations in the chronic phase after aneurysmal subarachnoid haemorrhage--is stress the culprit?

Spontaneous aneurysmal subarachnoid haemorrhage (SAH) is a cause of stroke, which constitutes a severe trauma to the brain and may lead to serious long-term medical, psychosocial and endocrinological sequelae. Adrenocorticotrophic hormone deficiency, which is considered to occur in up to 20% of all survivors, is a possible consequence of bleeding. Moreover, preliminary data suggest that a poor psychosocial outcome in SAH survivors is linked to alterations in cortisol secretion. Despite these findings, investigation of diurnal cortisol profiles and the cortisol awakening response (CAR) in chronic SAH patients has not been done so far. In this study, basal serum cortisol and salivary cortisol concentration profiles were investigated in 31 SAH patients more than 1 year after the acute event and in 25 healthy controls. Additionally, low-dose dexamethasone (DEX) suppression tests were conducted, and sensitivity to stress was measured with a psychometric questionnaire (Neuropattern(TM)). Although significantly higher salivary cortisol concentrations were observed on waking in SAH patients (p = 0.013, ANOVA), without a CAR change, total serum cortisol concentrations were blunted, but only in patients with high levels of perceived stress (SAH high stress: 337 nmol/l, SAH low stress: 442 nmol/l, controls: 467 nmol/l; Controls vs. SAH high stress p = 0.018). DEX suppression of cortisol secretion was not significantly different between patients and controls. The results indicate that total (serum) and free (salivary) cortisol concentrations give different information about cortisol availability in patients after aneurysmal SAH. Enhanced free cortisol concentrations may reflect a meaningful biological coping mechanism in SAH patients.

Pterional trephination approach to tumors of the infratemporal fossa

Tumors of the infratemporal fossa may extend superiorly into the middle cranial fossa and inferiorly into the retromaxillary space. Surgical removal commonly requires an interdisciplinary skull base team, which may have to approach the tumor from above and below in order to resect it. In an attempt to resect infratemporal fossa tumors of this magnitude with a single surgical approach, a pterional trephination (with or without removal of the zygomatic arch) was utilized in 13 cases to define its usefulness and limitations. In nine cases the histologic examination revealed a diagnosis of meningioma, in three, adenoid cystic carcinoma, and in one, undifferentiated carcinoma was found. Postoperative computed tomography was performed in all cases to assess the completeness of tumor resection. This article will detail the successful use of this single-stage approach to intra- or extradural lesions that originate in the infratemporal fossa.

Pterional/Lateral approach to orbital tumors

The purpose of this article is to detail our experience with an approach to primary pathologic conditions involving the orbit. In 27 patients these included tumors of the lacrimal gland, lymphangiomas, neurinomas, meningiomas, and various cysts of the orbit. Access to these lesions was gained by a lateral pterional approach with osteoclastic or osteoplastic removal of the lateral bony wall/roof of the orbit, and by entering adnexal contents following elevation of the lateral rectus muscle. This approach allowed for complete tumor removal in all patients. The specifics of this approach will be discussed and associated orbital complications will be detailed.

Growth hormone deficient patients after traumatic brain injury--baseline characteristics and benefits after growth hormone replacement--an analysis of the German KIMS database

OBJECTIVE

In recent years, traumatic brain injury (TBI) has been identified as a significant cause of growth hormone deficiency (GHD). The aim of the present study was to characterize adult TBI patients with GHD to elucidate the effect of human growth hormone (hGH) replacement in TBI patients as documented in the German Pfizer International Metabolic (KIMS) database.

DESIGN

As of October 2006, 84 TBI patients had been included in the German KIMS database (n=28 childhood-onset and 54 adult-onset GHD). All 84 TBI patients were matched with 84 patients with GHD due to non-functioning pituitary adenoma (NFPA) also included in this database. Analysis of clinical and outcome variables was performed, with comparisons of childhood vs. adult TBI, and TBI vs. NFPA patients, at baseline and one-year follow-up.

RESULTS

TBI patients with GHD were significantly younger at the onset of pituitary disease and exhibited a significantly longer time span between GHD diagnosis and KIMS entry than NFPA patients. Those KIMS patients who had sustained their TBI in childhood were of significantly shorter stature than adult-onset TBI patients. At 1-year follow-up, insulin-like growth factor I (IGF-I) standard deviation score levels had returned to the normal range and quality of life (QoL), as measured by QoL- Assessment of Growth Hormone Deficiency in Adults (AGHDA) questionnaire, improved significantly in TBI as in NFPA patients.

CONCLUSION

This analysis provides preliminary data that TBI patients with GHD benefit from hGH replacement in terms of improved QoL in a similar fashion as do NFPA patients. Moreover, it suggests that belated diagnosis and treatment in childhood-onset GHD due to TBI might be related to a shorter final height in these children.

A less invasive surgical concept for the resection of spinal meningiomas

BACKGROUND

The surgical strategy for spinal meningiomas usually consists of laminectomy, initial tumour debulking, identification of the interface between tumour and spinal cord, resection of the dura including the matrix of the tumour, and duroplasty. The objective of this study was to investigate whether a less invasive surgical strategy consisting of hemilaminectomy or laminectomy, tumour removal and coagulation of the tumour matrix allows comparable surgical and clinical results to be obtained, especially without an increase of the recurrence rate as reported in the literature.

PATIENTS AND METHODS

Between 1990 and 2005, 61 patients (11 men, 50 women) underwent surgery for spinal meningioma. All patients were treated microsurgically by a posterior approach. In 56 of the 61 patients, the above outlined - less invasive - surgical technique with tumour removal and coagulation of the tumour matrix was performed. In 5 patients, dura resection and duroplasty was additionally performed. Electrophysiological monitoring was routinely used since 1996. Recurrence was defined as new onset or worsening of symptoms and radiological confirmation of tumour growth. The pre-and post-operative clinical status was measured by the Frankel grading system.

RESULTS

Pre-operatively, 40 patients were in Frankel grade D, 13 patients in grade C, 6 patients in grade E and 1 patient each in grade A and B. Following surgery no patient presented a permanent worsening of clinical symptoms. All patients who initially presented with a Frankel grades A-C (n = 15) recovered to a better grade at the time of follow-up. Patients who presented with Frankel grade D remained in stable condition (n = 27) or recovered to a better neurological status (n = 13). Two patients experienced a temporary worsening of their symptoms, but subsequently improved to a better state than pre-operatively. Two (3.3%) complications (pseudomeningocele, wound infection) requiring surgery, were encountered. The pseudomeningocele developed in a patient who underwent durotomy. During the follow-up period of 2 months to 10 years (mean 31.3 months), 3 patients (5%) required surgery for symptomatic recurrence: 1 patient had 2 recurrences that occurred 4 and 7 years after first tumour removal and matrix coagulation, 1 recurrence occurred 1 year after tumour removal that was accompanied by matrix coagulation in a patient with a diffuse anterocranial tumour extension and 1 occurred 3 years after tumour removal and durotomy. Two patients showed a small recurrence on MRI during follow-up after 2 and 5 years, respectively, without any symptoms requiring surgery.

CONCLUSIONS

The high rate of favourable clinical results combined with the low rate of recurrences supports our less invasive surgical concept, which does not aim for resection of the dural matrix of the spinal meningioma.

Intramedullary hemangioblastomas: timing of surgery, microsurgical technique and follow-up in 23 patients

Hemangioblastomas are highly vascularised tumors of the central nervous system and account for 1.5-2.5% of all spinal cord tumors. Because of the rarity of these tumors, surgical experience is often limited and, therefore, treatment and indications for timing of surgery are discussed controversial. The authors reviewed their data of 23 consecutive patients with respect to timing of surgery, microsurgical technique, and follow-up. Clinical records of 23 consecutive patients with intramedullary hemangioblastomas who underwent first surgery in our department between 1990 and 2005 were reviewed. In three cases the tumors were localised at the craniocervical junction; four patients had a single tumor in the cervical spine, six patients multiple tumors in the cervical and thoracic spine, eight patients in the thoracic spine only, one patient in the conus region, and one patient had multiple tumors located in the thoracic and lumbar spine. In eight patients, a von-Hippel-Lindau disease (VHL) was associated. The neurological follow-up was evaluated according to the classification of McCormick. Operation was recommended to every symptomatic patient as early as possible. In asymptomatic patients with a sporadic tumor surgery was discussed for diagnostic purposes at any time. In VHL patients, surgery was recommended if tumor growth was observed on MRI in the next practicable time. All tumors were diagnosed by magnetic resonance imaging and in all cases but one a DSA was performed. All patients were treated microsurgically through a posterior approach. The tumors in the spinal cord were removed microsurgically through a partial hemilaminectomy (n = 1), a hemilaminectomy (n = 15), or laminectomy (n = 4) and at the craniocervical junction (n = 3) through a suboccipital craniotomy. During follow-up after 6 months, 18 patients remained neurologically stable (17 in McCormick grade I and 1 in McCormick grade II) and 5 patients recovered to a better status (3 from grade III to II, 2 from grade II to I). There was one complication with a CSF fistula and one recurrence/incomplete removal. Following the above-mentioned principles of microsurgical removal of intramedullary hemangioblastomas, operation is possible with a low procedure-related morbidity and can be recommended especially in VHL patients with progressive symptoms or tumor growth during follow-up. Patients without VHL most frequently require hemangioblastoma resection for diagnostic purposes and/or because symptoms prompted an imaging work-up that lead to the discovery of the tumor.

Transmuscular trocar technique - minimal access spine surgery for far lateral lumbar disc herniations

OBJECTIVE

Minimal access spine surgery (MASS) is gaining increasing importance in microsurgery of the lumbar spine. From a current prospective series we present data on MASS for far lateral lumbar disc herniations (LLDH) via a transmuscular trocar technique (T(2)). The surgical procedure and operative results are demonstrated in detail. In contrast to conventional percutaneous endoscopic techniques, T(2) allows one to operate in the typical microsurgical fashion combined with the advantages of a minimal endoscopic approach with three-dimensional visualization of the surgical target using the operating microscope.

METHODS

Microsurgery was performed through a 1.6-cm skin incision with an 11.5-mm diameter trocar that is obliquely inserted into the paraspinal muscles pointing at the lateral isthmus of the upper vertebral body. Fifteen patients were evaluated after a median follow-up period of 24 months. Overall outcome according to the modified MacNab criteria, effect of surgery on radicular pain and sensory or motor deficits, duration of surgery, complication rate, and duration of hospital stay were evaluated.

RESULTS

Good to excellent clinical outcomes were achieved in 14/15 patients. Radicular pain and motor deficits improved in all patients postoperatively, while sensory deficits recovered in 13/15 patients. The cosmetic results were excellent in all patients. No aggravation of symptoms after surgery was observed in any of the patients.

CONCLUSIONS

The T(2) technique represents an auspicious alternative to standard open microsurgery for LLDH, which allows achievement of excellent clinical and cosmetic results, preservation of segmental spine stability, and avoidance of excessive soft tissue trauma.

Management of hydrocephalus in children with plasminogen deficiency

Congenital plasminogen deficiency is an infrequent disorder, which usually becomes symptomatic as ligneous conjunctivitis. However, pseudomembranous lesions in the mucosa of the pharynx, tracheobronchial tree, and the peritoneum may likewise occur. An accompanying hydrocephalus is extremely rare; only 16 cases have been reported to date. The reports indicate that hydrocephalus, even if treated by ventriculoperitoneal (VP) cerebrospinal fluid (CSF) shunting, worsens the prognosis substantially. Thus, VP CSF shunting does not seem to be the optimal therapy for hydrocephalic children with plasminogen deficiency. We add two cases to the literature, and, on the base of our experience, we propose a management strategy for the hydrocephalus. We report the case history of two children with plasminogen deficiency and associated hydrocephalus. Both children initially were treated with VP shunts and had a very similar clinical course with multiple shunt malfunctions due to nonabsorption by the peritoneum. In the first child, the attempt to treat the hydrocephalus with a ventriculoatrial (VA) shunt failed due to catheter thrombosis. Finally, a ventriculocholecystic shunt was placed in both children, which worked well. In patients with plasminogem deficiency and associated hydrocephalus, special care must be taken in the management of hydrocephalus. The absorptive capacity of the peritoneum is reduced by pseudomembrane formation, which results in VP shunt malfunction. The plasminogen deficiency results in early thrombus formation if atrial catheters are used. Therefore, the authors believe that ventriculocholecystic shunting should be considered early on in the course of the disease.

Combined motor and somatosensory evoked potentials for intraoperative monitoring: intra- and postoperative data in a series of 69 operations

The primary objective of neurophysiologic monitoring during surgery is to avoid permanent neurological injury resulting from surgical manipulation. To prevent motor deficits, either somatosensory (SSEP) or transcranial motor evoked potentials (MEP) are applied. This prospective study was conducted to evaluate if the combined use of SSEP and MEP might be beneficial. Combined SSEP/MEP monitoring was attempted in 100 consecutive procedures, including intracranial and spinal operations. Repetitive transcranial electric motor cortex stimulation was used to elicit MEP from muscles of the upper and lower limb. Stimulation of the tibial and median nerves was performed to record SSEP. Critical SSEP/MEP changes were defined as decreases in amplitude of more than 50% or increases in latency of more than 10% of baseline values. The operation was paused or the surgical strategy was modified in every case of SSEP/MEP changes. Combined SSEP/MEP monitoring was possible in 69 out of 100 operations. In 49 of the 69 operations (71%), SSEP/ MEP were stable, and the patients remained neurologically intact. Critical SSEP/ MEP changes were seen in six operations. Critical MEP changes with stable SSEP occurred in 12 operations. Overall, critical MEP changes were recorded in 18 operations (26%). In 12 of the 18 operations, MEP recovered to some extent after modification of the surgical strategy, and the patients either showed no (n = 10) or only a transient motor deficit (n = 2). In the remaining six operations, MEP did not recover and the patients either had a transient (n = 3) or a permanent (n = 3) motor deficit. Critical SSEP changes with stable MEP were observed in two operations; both patients did not show a new motor deficit. Our data again confirm that MEP monitoring is superior to SSEP monitoring in detecting impending impairment of the functional integrity of cerebral and spinal cord motor pathways during surgery. Detection of MEP changes and adjustment of the surgical strategy might allow to prevent irreversible pyramidal tract damage. Stable SSEP/MEP recordings reassure the surgeon that motor function is still intact and surgery can be continued safely. The combined SSEP/ MEP monitoring becomes advantageous, if one modality is not recordable.

Electrophysiological Proof of Diffusion-Weighted Imaging-Derived Depiction of the Deep-Seated Pyramidal Tract in Human

In the living human brain the pyramidal tract (PT) can be displayed with magnetic resonance diffusion-weighted imaging (DWI). Although this imaging technique is already being used for planning and performing neurosurgical procedures in the PT vicinity, there is a lack of verification of DWI accuracy in other areas outside the directly subcortical PT parts. Before definitive electrode placement into the subthalamic nucleus (STN) in patients with Parkinson disease (PD) for chronic stimulation, the stimulation effect on PD symptoms and the side-effects, namely PT activation at the level of the internal capsule (IC), are electrophysiologically tested. To analyze DWI accuracy by matching the stereotactic coordinates of the electrophysiologically proven IC position with these of the DWI-derived IC display, DWI was added to the routine MRI work-up in the stereotactic frame prior to functional surgery in 6 patients. In all of the 10 displayed fiber tracts, concordant findings for imaging and macrostimulation were made. The authors proved for the first time that DWI correctly depicts the deep seated, principle motor pathways in the living human brain. Due to methodical limitations of this study the accuracy of the proven IC display is limited to 3 mm which has proven to be sufficient for the planning and performance of neurosurgical procedures in the vicinity of large fiber tracts.

A rare but life-threatening complication of ventriculo-atrial shunt

Insertion of ventriculoperitoneal and ventriculoatrial shunts is routinely performed. Infarction pneumonia and atrial thrombus formation are described as very rare complications of ventriculoatrial shunts. We present the case of a female patient with ventriculoatrial shunt insertion as long term treatment for aequeductal stenosis who presented with recurrent episodes of dyspnoea, chest pain, and unilateral pleural effusion. Diagnostic evaluation revealed a positive D-dimer test, bilateral basal infiltrates and pleural effusion. Transesophageal echocardiography established the diagnosis of a thrombus in the right atrium. Laboratory testing for thrombophilia revealed a homozygous factor V Leiden mutation. In the following, a shunt revision was performed.

Technical pitfalls in a porcine brain retraction model

We describe technical pitfalls of a porcine brain injury model for identifying primary and secondary pathological sequelae following brain retraction by brain spatula. In 16 anaesthetised male pigs, the right frontal brain was retracted in the interhemispheric fissure by a brain spatulum with varying pressures applied by the gravitational force of weights from 10 to 70 g for a duration of 30 min. The retracted brain tissue was monitored for changes in intracranial pressure and perfusion of the cortex using a Laser Doppler Perfusion Imager (MoorLDI). To evaluate the extent of oedema and cortical contusions, MRI was performed 30 min and 72 h after brain retraction. Following the MR scan, the retracted brain areas were histopathologically assessed using H&E and Fluoro-Jade B staining for neuronal damage. Sinus occlusion occurred in four animals, resulting in bilateral cortical contusions and extensive brain oedema. Retracting the brain with weights of 70 g (n = 4) caused extensive oedema on FLAIR images that correlated clinically with a hemiparesis in three animals. Morphologically, an increased number of Fluoro-Jade B-positive neurons were found. A sequential decrease in weights prevented functional deficits in animals. A retraction pressure applied by 10-g weights (n = 7) caused a mean rise in intracranial pressure to 4.0 +/- 3.1 mm Hg, and a decrement in mean cortical perfusion from 740.8 +/- 41.5 to 693.8 +/- 72.4 PU/cm2 (P < 0.24). A meticulous dissection of the interhemispheric fissure and a reduction of weights to 10 g were found to be mandatory to study the cortical impact caused by brain spatula reproducibly.

Motor evoked potentials following highly frequent transcranial magnetoelectrical motor cortex stimulation: normal data and potential modulation by stimulation-dependent inhibitory and activating mechanisms

OBJECTIVE

To determine the normal values (latency, amplitude) of motor evoked potentials (MEP) of the abductor pollicis brevis (APB) and tibialis anterior (TA) muscle after high-frequency repetitive transcranial magnetic stimulation of the motor cortex (rTCMS), and to evaluate stimulation-dependent MEP modulations.

PATIENTS AND METHODS

29 healthy volunteers underwent rTCMS with 2 and 4 stimuli. The interstimulus interval (ISI) was 2, 3, and 4 ms respectively, which corresponded to frequencies between 250 and 500 stimuli/s. The evoked potentials of the relaxed and voluntarily contracted APB and TA were registered.

RESULTS

Depending on the frequency and number of stimuli, the mean corticomuscular latency to the relaxed APB varied between 22.2 and 22.9 ms, and to the relaxed TA between 30.4 and 32.0 ms. The intra- and interindividual variability of the amplitudes was substantial. Voluntary contraction of the target muscle always led to a decrease in latency and increase in amplitude (p < 0.05).

CONCLUSION

The high variability of the amplitudes does not allow the computation of meaningful normal values. The latencies after rTCMS are close to those of normal data after single TCMS, which indicates that in awake humans identical cortical and spinal structures are similarly activated. The discrete variations of latency and amplitude after changing the frequency and stimulus number suggest that inhibitory and excitatory mechanisms on the cortical and/or spinal level modulate the muscle response.

Lateral transmuscular or combined interlaminar/paraisthmic approach to lateral lumbar disc herniation? A comparative clinical series of 48 patients

BACKGROUND

The optimum operative technique for lateral lumbar disc herniations (LLDH) remains unclear, and both interlaminar and extraspinal approaches are used.

OBJECTIVE

To compare outcome after LLDH removal either by a lateral transmuscular approach (LTM) or by a combined interlaminar and paraisthmic approach (CIP).

METHODS

28 patients underwent surgery using CIP and 20 using LTM. All patients were operated on by the same neurosurgeon. The clinical presentation of the two groups was comparable. Overall outcome was assessed after a mean follow up period of between 19 and 37 months using the Ebeling classification. In addition, the effect of surgery on radicular pain, low back pain, and sensory and motor deficits was defined.

RESULTS

Excellent to good results were achieved in 95% of the LTM group and 57% of the CIP group. The outcome was satisfactory to poor in 5% of the LTM and 43% of the CIP group (p<0.004). The percentage of sensorimotor deficit and of radicular pain improvement was higher in the LTM group. New low back pain was found exclusively in the CIP group (21%). The complication rate was 5% in the LTM group and 11% in the CIP group.

CONCLUSIONS

The LTM approach achieves a better overall outcome and improvement in radiculopathy. The complication rate is lower with the transmuscular route and the risk of new low back pain is minimised. These results are likely to be attributable at least in part to the lesser invasiveness of the LTM approach.

Head Injury after a Fall on Stairs: Poorer Prognosis in Inebriated Patients?

AIM

The aim of the present study was to determine whether inebriated patients falling on stairs sustain more severe head injuries than sober patients because of a delayed reaction time and a pathological coagulation and clotting system.

PATIENTS AND METHODS

The files of 140 head-injured patients who came to admission after falling on stairs were retrospectively reviewed with respect to demographic data, initial Glasgow coma scale (GCS) score, type of hematoma, coagulation parameters and outcome (death versus survival, Glasgow Outcome Scale [GOS] score GOS 3-5 vs. GOS 1 and 2).

RESULTS

There were 69 patients who had an alcohol level of > or = 0.8 parts per thousand at the time of the fall (49.0 %). The mortality in the group of inebriated patients was 12.9 %, in the group of sober patients 33.3 % (p = 0.001). The characteristics of the two groups were comparable, except for age (50.4 vs. 69.1 years, p = 0.001). The analysis of mortality in relation to age confirmed the finding of a lower mortality rate in inebriated patients.

CONCLUSION

The hypothesis that inebriated patients sustain more severe head injuries with higher mortality rates could not be validated. Routine laboratory tests did not detect coagulation and clotting disorders in inebriated patients. Instead, our study again showed that age is one of the major prognostic factors in head injury.

Diffusion-weighted imaging-guided resection of intracerebral lesions involving the optic radiation

In this paper we report our experience with diffusion-weighted imaging (DWI) for optic radiation (OR) visualization during resection of tumors. We hypothesize that intraoperative OR visualization helps to maintain patients' visual fields. DWI studies were performed together with T1-weighted postcontrast magnetic resonance imaging (MRI) in four patients with lesions in or adjacent to the OR (glioblastoma, oligo-astrocytoma, cavernoma, and metastasis; n = 1 each). The OR was identified from one of six DWI data acquisitions, segmented and reconstructed three-dimensionally. The image data were neuronavigationally transferred into the operative field, and provided the neurosurgeon with information on lesion site and adjacent OR localization. Preoperative and postoperative neuroophthalmological testing included, among others, perimetry to define the value of diffusion-weighted image guidance during OR lesion resection. Three lesions were removed completely. In one case, low-grade tumor parts infiltrating the OR were intentionally left. No persistent visual field deficits were induced. In one patient, a transient homonymous hemianopia attributable to postoperative swelling completely resolved under steroid medication. The authors conclude that intraoperative OR visualization, realized by neuronavigationally displayed DWI data, might prove to be helpful to maintain patients' visual fields.

Advanced Neuronavigation in Skull Base Tumors and Vascular Lesions

OBJECTIVE

The purpose of this study was to describe the usefulness of recent advances of neuronavigational technology in the management of skull base tumors and of vascular lesions, treated via a skull base approach.

METHODS

In 16 patients (skull base meningioma n = 9, petrous apex epidermoid n = l, craniopharyngeoma n = 1, giant internal carotid artery aneurysm n = 1, basilar/vertebral artery aneurysm n = 2, brain stem cavernoma n = 2), "advanced" neuronavigation was used. In contrast to "conventional" neuronavigation, the information for the neurosurgeon was enhanced by the intraoperative screen display of 3-dimensional reconstructions of the lesion, vessels, nerves and fiber tracts at risk. The 3-dimensional reconstructions were obtained by preoperative manual or automated segmentation processes. In addition, different imaging modalities (computed tomography [CT] with magnetic resonance imaging [MRI], CT with CT angiography, T (l)- with diffusion-weighted MRI) were fused and shown on the screen.

RESULTS

In the cases of tumors, "advanced" neuronavigation facilitated the approach (n = 4), contributed to tailor the approach (n = 2) and helped to identify hidden neurovascular structures (n = 9). In the cases of aneurysms, "advanced" neuronavigation allowed us to reduce the skull base approach to the needs of safe aneurysm clipping (n = 3). In both cases of brain stem cavernoma, "advanced" neuronavigation was deemed useful for definition of the best surgical approach in relation to the pyramidal tract and brain stem nuclei.

CONCLUSION

The authors' experiences suggest that neuronavigation, which displays 3-dimensional reconstructions of lesion, vessels, nerves and fiber tracts during surgery and makes use of image fusion techniques, is an important tool in the neurosurgical management of skull base lesions.

Image-guided microneurosurgical management of small cerebral arteriovenous malformations: the value of navigated computed tomographic angiography

In small arteriovenous malformations (AVM) with large hematomas, surgery remains the main therapeutic option. However, intraoperative identification of the AVM, feeders, and draining veins could be difficult in the environment of substantial intracerebral blood. In those selected cases, we use navigated computed tomographic angiography (CTA) for the microneurosurgical management. It is our objective to report our initial experiences. Prior to operation a conventional CTA with superficial skin fiducials placed on a patient's head was acquired for diagnostic and neuronavigation purposes. Image data were transferred to a neuronavigation device with integrated volume rendering capacities which allows a three-dimensional reconstruction of the vascular tree and the AVM to be created. In all patients the AVM was removed successfully after having been localized with CTA-based neuronavigation. Navigated CTA is helpful for the operative management of small AVMs with large hematomas. The technique allows feeding arteries to be distinguished from draining veins thereby allowing the nidus of the AVM to be identified despite the presence of substantial intracerebral blood. CTA can be easily implemented into commercial neuronavigation systems.