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Andreas Raabe and Volker Seifert

✓ The S-100B protein is a small cytosolic protein that is found in astroglial or Schwann cells. It is highly specific for brain tissue and is increasingly being investigated as a diagnostic tool to assess the neurological damage after head injury, stroke, subarachnoid hemorrhage, and cardiopulmonary bypass.

The authors report on three patients with severe head injury with otherwise normal cerebral perfusion pressure, SaO2, PaCO2, and controlled intracranial pressure (ICP), in whom a secondary excessive increase in serum S-100B was observed. In all cases, the S-100B increase was followed by an increase in ICP. All three patients died within 72 hours after the excessive increase in S-100B. These findings indicate that major secondary brain damage may occur at a cellular level without being identified by current neuromonitoring techniques.

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Volker Seifert and Dietmar Stolke

Aneurysms of the basilar trunk and vertebrobasilar junction represent an exceptional challenge to the neurosurgeon. Surgical access to these deep and confined lesions is hampered by the direct proximity of highly vulnerable neural structures such as the brainstem and cranial nerves, as well as by the structure of the petrous bone, which blocks direct surgical approach to these aneurysms. A number of surgical tactics consisting of different supra- and infratentorial approaches have been applied over the years to gain access to these treacherous lesions. Only recently have lateral approaches, such as the anterior transpetrosal, the retrolabyrinthine-transsigmoidal, and the combined supra/infratentorial-posterior transpetrosal approaches, directed through parts of the petrous bone, been reported for surgery of basilar trunk and vertebrobasilar junction aneurysms. Because detailed reports of direct operative intervention using the transpetrosal route for these rare and difficult lesions are scarce, the authors present their surgical experiences in nine patients with basilar trunk and vertebrobasilar junction aneurysms, in whom they operated via the supra/infratentorial-posterior transpetrosal approach. In eight patients, including one with a giant partially thrombosed basilar trunk aneurysm, direct clipping of the aneurysm via the transpetrosal route was possible. In one patient with a giant vertebrobasilar junction aneurysm, the completely calcified aneurysm sac was resected after occlusion of the vertebral artery. In total, one patient died and another experienced postoperative accentuation of preexisting cranial nerve deficits. Two patients had transient cerebrospinal fluid leakage, and the postoperative course was uneventful in the remaining seven. Postoperative angiography demonstrated complete aneurysm clipping in eight patients and relief of preoperative brainstem compression in the patient with the giant vertebrobasilar junction aneurysm. It is concluded that the supra/infratentorial-posterior transpetrosal approach allows excellent access to the basilar artery trunk and vertebrobasilar junction and can be considered the approach of choice to selected aneurysms located in this area.

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Volker Seifert and Dietmar Stolke

✓ Aneurysms of the basilar trunk and vertebrobasilar junction represent an exceptional challenge to the neurosurgeon. Surgical access to these deep and confined lesions is hampered by the direct proximity of highly vulnerable neural structures such as the brainstem and cranial nerves, as well as by the structure of the petrous bone, which blocks direct surgical approach to these aneurysms. A number of surgical tactics consisting of different supra- and infratentorial approaches have been applied over the years to gain access to these treacherous lesions. Only recently have lateral approaches, such as the anterior transpetrosal, the retrolabyrinthine—transsigmoidal, and the combined supra/infratentorial—posterior transpetrosal approaches, directed through parts of the petrous bone, been reported for surgery of basilar trunk and vertebrobasilar junction aneurysms. Because detailed reports of direct operative intervention using the transpetrosal route for these rare and difficult lesions are scarce, the authors present their surgical experiences in nine patients with basilar trunk and vertebrobasilar junction aneurysms, in whom they operated via the supra/infratentorial—posterior transpetrosal approach. In eight patients, including one with a giant partially thrombosed basilar trunk aneurysm, direct clipping of the aneurysm via the transpetrosal route was possible. In one patient with a giant vertebrobasilar junction aneurysm, the completely calcified aneurysm sac was resected after occlusion of the vertebral artery. In total, one patient died and another experienced postoperative accentuation of preexisting cranial nerve deficits. Two patients had transient cerebrospinal fluid leakage, and the postoperative course was uneventful in the remaining seven. Postoperative angiography demonstrated complete aneurysm clipping in eight patients and relief of preoperative brainstem compression in the patient with the giant vertebrobasilar junction aneurysm. It is concluded that the supra/infratentorial—posterior transpetrosal approach allows excellent access to the basilar artery trunk and vertebrobasilar junction and can be considered the approach of choice to selected aneurysms located in this area.

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Jens Fichtner, Erdem Güresir, Volker Seifert and Andreas Raabe

Object

Catheter-related infection of CSF is a potentially life-threatening complication of external ventricular drainage (EVD). When using EVD catheters, contact between the ventricular system and skin surface occurs and CSF infection is possible. The aim of this analysis was to compare the efficacy of silver-bearing EVD catheters for reducing the incidence of infection with standard nonimpregnated EVD catheters in neurosurgical patients with acute hydrocephalus.

Methods

Two hundred thirty-one consecutive patients were retrospectively reviewed. Of these, 164 were enrolled in the final analysis. Six patient charts were incomplete or missing, 15 patients were excluded because of catheter insertion within the previous 30 days, 6 because of a suspected CSF infection before ventriculostomy, 7 because the catheter was removed < 24 hours after insertion, and 33 patients because of the requirement of bilateral ventriculostomy. The control group with standard nonimpregnated EVD catheters consisted of 90 patients. The study group with silver-bearing EVDs consisted of 74 patients. For assessing the primary outcome, the authors recorded all CSF samples and liquor cell counts routinely obtained in sterile fashion. After removal of the catheters, they also reviewed microbiology reports of the removed catheters to assess colonization of the catheter tips.

Results

The occurrence of a positive CSF culture, colonization of the catheter tip, or liquor pleocytosis (white blood cell count > 4/μl) was ~ 2 times less in the study group with silver-bearing EVD catheters than that in the control group (18.9% compared with 33.7%, p = 0.04). Positive CSF cultures alone occurred 2 times less frequently for microorganisms in the study group (2.7% compared with 4.7%, p = 0.55). Silver-bearing catheters were 4 times less likely to become colonized as nonimpregnated EVDs (1.4% compared with 5.8%, p = 0.14). Liquor pleocytosis was half as likely in the study group (17.6% compared with 30.2%, p = 0.06).

Conclusions

Although of limited sample size and thus underpowered for subgroup analysis, this analysis indicates that EVD catheters impregnated with silver nanoparticles and an insoluble silver salt may reduce the risk of catheter-related infections in neurosurgical patients.

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Thomas Brinker, Volker Seifert and Dietmar Stolke

✓ The effect of intrathecal fibrinolysis on cerebrospinal fluid (CSF) absorption was investigated after experimental subarachnoid hemorrhage (SAH). In 11 cats, SAH was induced by intracisternal application of 1 to 4 ml of fresh autologous blood. Thirty minutes after the experimental SAH, the CSF outflow resistance was found to be elevated from a median of 77 mm Hg/ml/min (range 41.3 to 109 mm Hg/ml/min) to a median of 580 mm Hg/ml/min (range 104 to 7000 mm Hg/ml/min). A logarithmic relationship could be demonstrated between the volume of subarachnoid blood and the elevation of the CSF outflow resistance. The intrathecal application of 2 mg of recombinant tissue plasminogen activator (rt-PA), which is a fibrinolytic substance suitable for lysis of subarachnoid blood clots in man, resulted in an almost total restoration of CSF absorption after experimental SAH. The CSF outflow resistance after SAH was lowered by application of rt-PA from a median of 1028.05 mm Hg/ml/min (range 394 to 7000 mm Hg/ml/min) to 79 mm Hg/ml/min (range 56.7 to 223 mm Hg/ml/min). It is concluded that the impairment of CSF absorption after SAH may play an important role in the pathogenesis of post-hemorrhagic vasospasm.

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Hans-Ekkehart Vitzthum, Alexander König and Volker Seifert

Object. The aim of this study was to determine the relationship of different structures of the lower lumbar spine during interventional movement examination.

Methods. Clinically healthy volunteers and patients suffering from degenerative disorders of the lumbar spine underwent vertical, open magnetic resonance (MR) imaging (0.5 tesla). Three functional patterns of lumbar spine motion were identified in 50 healthy volunteers, (average age 25 years). The authors identified characteristic angles of the facet joints, as measured in the frontal plane. In 50 patients with degenerative disorders of the lumbar spine (41 with disc herniation, five with osteogenic spinal stenosis, and four with degenerative spondylolisthesis) the range of rotation was increased in the relevant spinal segments. Signs of neural compression were increased under motion.

Conclusions. Dynamic examination in which vertical, open MR imaging is used demonstrated that the extent of neural compression as well as the increasing range of rotation are important signs of segmental instability.

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Gerhard Marquardt, Soledad M. Barduzal Angles, Fouad D. Leheta and Volker Seifert

✓ A rare case of peripheral-nerve compression in the upper arm caused by a spontaneous venous aneurysm is reported. The apparent dysfunction of the median nerve led to various vain surgical explorations of the nerve at different levels. The real localization of nerve entrapment was identified by a thorough clinical examination, and sonography yielded a correct diagnosis. Surgical resection of the venous aneurysm resulted in complete relief of pain. To the authors' knowledge, this is the first report of a spontaneous venous malformation in the upper arm causing focal neuropathy.

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Kunihiko Kodama, Mani Javadi, Volker Seifert and Andrea Szelényi

Object

During the surgical removal of infratentorial lesions, intraoperative neuromonitoring is mostly focused on cranial nerve assessment and brainstem auditory potentials. Despite the known risk of perforating vessel injury during microdissection within the vicinity of the brainstem, there are few reports about intraoperative neuromonitoring with somatosensory evoked potentials (SEPs) and motor evoked potentials (MEPs) assessing the medial lemniscus and corticospinal tract. This study analyses the occurrence of intraoperative changes in MEPs and SEPs with regard to lesion location and postoperative neurological outcome.

Methods

The authors analyzed 210 cases in which patients (mean age 49 ± 13 years, 109 female) underwent surgeries involving the skull base (n = 104), cerebellum (n = 63), fourth ventricle (n = 28), brainstem (n = 12), and foramen magnum (n = 3).

Results

Of 210 surgeries, 171 (81.4%) were uneventful with respect to long-tract monitoring. Nine (23%) of the 39 SEP and/or MEP alterations were transient and were only followed by a slight permanent deficit in 1 case. Permanent deterioration only was seen in 19 (49%) of 39 cases; the deterioration was related to tumor dissection in 4 of these cases, and permanent deficit (moderate-severe) was seen in only 1 of these 4 cases. Eleven patients (28%) had losses of at least 1 modality, and in 9 of these 11 cases, the loss was related to surgical microdissection within the vicinity of the brainstem. Four of these 9 patients suffered a moderate-to-severe long-term deficit. For permanent changes, the positive predictive value for neuromonitoring of the long tracts was 0.467, the negative predictive value was 0.989, the sensitivity was 0.875, and the specificity 0.918. Twenty-eight (72%) of 39 SEP and MEP alterations occurred in 66 cases involving intrinsic brainstem tumors or tumors adjacent to the brainstem. Lesion location and alterations in intraoperative neuromonitoring significantly correlated with patients' outcome (p < 0.001, chi-square test).

Conclusions

In summary, long-tract monitoring with SEPs and MEPs in infratentorial surgeries has a high sensitivity and negative predictive value with respect to postoperative neurological status. It is recommended especially in those surgeries in which microdissection within and in the vicinity of the brainstem might lead to injury of the brainstem parenchyma or perforating vessels and a subsequent perfusion deficit within the brainstem.