Dietmar Stolke

Intra- and postoperative complications in lumbar disc surgery.

In a prospective study, 412 primary and 69 reoperations for herniated lumbar disc were observed and intra- and postoperative complications compiled. Only surgeons with the experience of more than 100 surgical procedures on lumbar discs entered this study. The complication rates of the micro- and macrosurgical techniques are compared. Intraoperative complications range from 7.8% in the microdiskectomies and 13.7% in the macrodiskectomies to 27.5% in the reoperations. Postoperative complications range from 1.4% in reoperation, 3.9% in the microdiskectomies up to 4.2% in the macrodiskectomies. The risk of complications correlates with the age of the patient and the operating time

Intradiscal Pressure Recordings in the Cervical Spine

OBJECTIVE Experimental investigations analyzing the biomechanics of the cervical spine are less common than similar studies of other regions of the spine. There are no reports on cervical intradiscal pressure (PID) measurements in vitro. We therefore wanted to establish normal values for PID under physiological conditions by simultaneous muscle force simulation. Moreover, the impact of ventral cervical fusion should be elucidated, because in clinical studies, it is a well-known phenomenon that the adjacent segments often show increased degenerative changes. We present a pilot study. METHODS Seven human cervical spine specimens were tested biomechanically in a specially developed spine tester. Only pure moments were used for flexion/extension, axial rotation, and lateral bending (maximal moment +/- 0.5 Nm). PID was measured simultaneously in C3-C4 and C5-C6. The specimens were tested as intact specimens and after discectomy and fusion in C4-C5. Both test situations were repeated with simulation of muscle forces. RESULTS We found characteristic load-pressure curves for each of the three motion axes. In neutral position, PID correlated well with former published data from in vivo measurements. After fusion of C4-C5, there was a marked increase of PID in both adjacent segments (e.g., < or = 180% for axial rotation). With muscle force simulation, the increase was even higher (e.g., < or = 400% for axial rotation). CONCLUSION For the first time, PID could be measured in the cervical spine in an experimental setting. The results obtained using normal specimens under physiological conditions confirmed those reported in two clinical studies. After cervical fusion, a marked increase in PID could be found in both adjacent segments. Presuming that an increase in PID had a negative effect on metabolism of the intervertebral disc, our results may help to explain why progressive degeneration occurs in these segments.

Secretion of sHLA-G molecules in malignancies.

Our clinical studies revealed significantly increased soluble HLA-G (sHLA-G) plasma levels in patients suffering from malignant melanoma, glioma, breast and ovarian cancer. Specific ELISpot assays demonstrate that sHLA-G molecules expressing intron-4 sequences are preferentially secreted by peripheral blood monocytes. In vitro, the sHLA-G secretion of monocytes and tumor cells was strongly enhanced by TH1 cytokines like IFN-alpha, -beta, -gamma whereas TH2 cytokines (e.g. IL-4, -10) had minor effects. As sHLA-G can inhibit the functions of T and NK cells high concentration of these molecules should systemically or at the tumor side reduce the immune surveillance and thus favour the progression of cancer.

Brain diffusion after single seizures.

Summary:  Purpose: Diffusion‐weighted magnetic resonance imaging (DWI) after focal status epilepticus has demonstrated focal alterations of the apparent diffusion coefficient (ADC) in the epileptogenic zone. We hypothesized that localized dynamic alterations of brain diffusion during the immediate postictal state will be detectable by serial DWI and correlate with the epileptogenic zone.

Intraoperative functional MRI: Implementation and preliminary experience

For a non-invasive identification of eloquent brain areas in neurosurgical procedures up to now only preoperative functional brain mapping techniques are available. These are based, e.g., on preoperative functional magnetic resonance imaging (fMRI) investigations in awake patients. The aim of this study was to investigate the feasibility to perform fMRI during neurosurgical procedures in anesthetized patients. For that purpose, a passive stimulation paradigm with peripheral nerve stimulation was applied. A 1.5-T MR scanner placed in a radiofrequency-shielded operating room with an adapted operating table was used for intraoperative fMRI. The fMRI data were analyzed during acquisition by an online statistical evaluation package installed on the MR scanner console. In addition, phase reversal of somatosensory evoked potentials was used for verification of intraoperative fMRI. In four anesthetized patients with lesions in the vicinity of the central region a total of 11 fMRI measurements were successfully acquired and analyzed online. Activation was found in the somatosensory cortex, which could be confirmed by intraoperative phase reversal for each measurement. Furthermore, statistical parametric mapping (SPM) was employed for an extensive offline data analysis. We did not observe any neurological deterioration or complications due to the stimulation technique. Intraoperative fMRI is technically feasible allowing a real-time identification of eloquent brain areas despite brain shift.

Foramen magnum meningiomas: clinical outcome after microsurgical resection via a posterolateral suboccipital retrocondylar approach.

OBJECTIVEWe analyzed a consecutive series of patients operated for a foramen magnum (FM) meningioma located on the ventral aspect of the medulla oblongata via a posterolateral suboccipital retrocondylar approach with regard to long-term surgical outcome. METHODSClinical data in a consecutive series of 25 patients experiencing a meningioma attached to dura of the anterior or anterolateral FM rim were retrospectively reviewed. RESULTSThe most common symptoms of the 19 women and six men (mean age, 59.2 yr) was cervico-occipital pain (72%) and gait disturbance (32%). Clinical examination revealed gait ataxia in 48% of the patients. As depicted from preoperative magnetic resonance imaging (MRI), dural attachment of the meningioma at the FM rim was anterior in 36% and anterolateral in 64% of cases. Tumor removal was accomplished via a posterolateral suboccipital retrocondylar approach in all patients. A Simpson Grade 2 resection was achieved in 96% of the patients. Permanent surgical morbidity and mortality rates were 8 and 4%, respectively. No tumor recurrence was observed after a mean follow-up period of 6.1 years (range, 1–14 yr) with clinical and MRI examination, and 80% of the patients have regained full daily activity. CONCLUSIONAnterior and anterolateral FM meningiomas that displace the medulla/spinal cord can be safely and completely resected via a posterolateral suboccipital retrocondylar approach. A tumor remnant should be left on critical neurovascular structures in cases with poor arachnoid dissection planes.

Analysis of intrathecal interleukin-6 as a potential predictive factor for vasospasm in subarachnoid hemorrhage

OBJECTIVEInflammatory response seems to be one of the relevant pathophysiological aspects for developing vasospasm in subarachnoid hemorrhage. The probable diagnostic value of intrathecal proinflammatory markers is still unclear and is assessed in this study. METHODSWe analyzed daily clinical data and laboratory tests of the cerebrospinal fluid (CSF) of 64 patients with mostly poor-grade subarachnoid hemorrhage during a period of 14 days. Special attention was given to the relationship between the development of vasospasm and the time course of the intrathecal interleukin (IL)-6 concentrations in CSF (IL-6CSF). The potential power of IL-6CSF for predicting vasospasm was studied. RESULTSVasospasm developed in 28.1% of the patients, with a mean onset of 6.4 days after bleeding, and was detected by conventional methods. Patients with vasospasm demonstrated statistically significant higher median values of IL-6CSF on Days 4 and 5 (P < 0.05). Most importantly, the increase of IL-6CSF preceded the conventional signs of vasospasm. A cut-off value of IL-6CSF of at least 2000 pg/ml on Day 4 yielded an 11.72-fold higher relative risk (95% confidence interval, 2.93–46.60) of developing vasospasm, predicting vasospasm with a sensitivity of 88.9% and a specificity of 78.3%. We found a statistically significant correlation between IL-6CSF and delayed cerebral ischemia for Day 7 (P = 0.03). However, there was no correlation with IL-6CSF on any other day and outcome. CONCLUSIONIL-6CSF seems to be a reliable early marker for predicting vasospasm after subarachnoid hemorrhage on Days 4 and 5 before clinical onset.

Efficacy of Single Intracisternal Bolus Injection of Recombinant Tissue Plasminogen Activator to Prevent Delayed Cerebral Vasospasm after Experimental Subarachnoid Hemorrhage

Premature lysis of subarachnoid blood clots by thrombolytic substances such as urokinase and plasmin has been shown to be efficacious in preventing cerebral vasospasm in clinical and experimental investigations. Recently, tissue plasminogen activator (rtPA) derived from recombinant deoxyribonucleic (DNA) technology has been introduced as a new thrombolytic substance. With its high affinity for fibrin-bound plasminogen and low affinity for circulating plasminogen by which a clot-selective fibrinolysis can be achieved without the danger of inducing systemic fibrinogenolysis, rtPA might be the ideal substance for the postoperative lysis of cisternal blood accumulations after subarachnoid hemorrhage. The efficacy of rtPA in preventing delayed cerebral vasospasm after experimental subarachnoid hemorrhage using a single intracisternal bolus injection of this agent was investigated. With a single injection of 25 micrograms of rtPA into the cisterna magna 48 hours after the first and 6 hours after the second injection of blood in the two-hemorrhage model of cerebral vasospasm, angiographic spasm of the basilar artery was completely prevented in all animals so treated whereas in the control group severe vasospasm occurred. Autopsy studies of the experimental animals demonstrated that the subarachnoid blood clots were almost completely removed by intracisternal rtPA application. Additionally the pathomorphological signs of proliferative vasculopathy present in all animals of the control group were not demonstrable in the rtPA group. As intracisternal bolus injection of rtPA is highly efficacious in preventing angiographic as well as pathomorphological vasospasm, it is concluded that use of this thrombolytic substance might be a promising approach for pharmacological blood clot removal.

Clipping versus coiling: neuropsychological follow up after aneurysmal subarachnoid haemorrhage (SAH).

ABSTRACT Patients treated with microsurgical clipping of ruptured intracranial aneurysms often suffer from neuropsychological deficits in spite of a good neurological outcome. The purpose of this study was to explore if the deficits are related to the type of therapy. Two groups of 16 patients each suffering from aneurysmal SAH, matched for sex, age, aneurysm-site and Hunt and Hess score, and 16 control subjects were examined with a battery of neuropsychological tests including memory, attention, and executive function. Depression, mood, and quality of life were also assessed. One patient group had been treated with surgical clipping, the other with endovascular coiling. Both patient groups showed deficits in verbal and visual memory. Clipped patients were slightly more impaired than coiled patients, especially on measures of affect and on a self-assessment measure of executive function. The pattern of results suggests that the neuropsychological outcome after aneurysmal SAH is affected by both the severity of the bleeding and the type of therapy.

Multisegmental cervical spondylosis: treatment by spondylectomy, microsurgical decompression, and osteosynthesis.

Vertebral body replacement after spondylectomy, combined with microsurgical decompression and anterior plating, was performed in 22 patients as an aggressive therapeutic approach to multisegmental cervical spondylosis. The patients were 13 men and 9 women, ranging in age from 32 to 74 years. In 19 patients, the typical signs of cervical myelopathy were present. In three patients, pain was the major symptom, accompanied by moderate spastic paresis and hyperreflexia. Apart from cervical myelography and computed tomographic scanning, which was performed in 10 patients, magnetic resonance imaging was the radiological procedure of choice in 12 patients. During spondylectomy, one vertebra was removed in 14 patients, two vertebrae in seven patients, and three vertebrae in one patient. The time of postoperative follow-up ranged from 8 to 46 months, with an average interval of 21 months. In all 22 patients, satisfactory bony fusion was achieved as demonstrated by radiological control examinations. Seventeen patients (77%) were symptom free or had only minor residual symptoms. Three (14%) patients had intermittent nuchal or cervicobrachial pain, which responded well to analgesic medication or the application of a soft collar. Two (9%) patients still had myelopathic but not incapacitating symptoms. Of 15 patients who were employed before surgery, 13 returned to a full-time job. The only severe complication of surgery was a prevertebral abscess that healed without sequelae. It is concluded that aggressive surgical therapy of multisegmental cervical spondylosis by a combination of vertebrectomy, decompression (using the surgical microscope), bone grafting, and osteosynthesis is a straightforward and promising procedure for the treatment of this debilitating disease.