Hans-Peter Richter

Neurosurgical management of thoracic and lumbar vertebral osteomyelitis and discitis in adults: a review of 43 consecutive surgically treated patients.

We report 43 consecutive surgically treated patients with pyogenic (37 patients) and tuberculous (6 patients) osteomyelitis of the thoracic and lumbar spine encountered within an 8-year period, including 1 with late recurrence after 15 months. There were 24 men and 18 women, ranging in age from 21 to 83 years. Twenty-six patients were in poor general condition because of associated illnesses, especially diabetes mellitus. Disease occurred at the thoracic level in 19 patients and on the lumbar spine in 24. After diagnosis, five patients were merely treated by posterior decompression; three of them, however, required further surgery for recurrent infection, spinal instability, and secondary neurological impairment. They are included in the 40 patients who underwent combined posterior débridement and internal fixation with transpedicular screw-rod systems. Autologous interbody bone grafting was performed simultaneously in 18 patients and in a second stage operation in 21 patients. One of them (tuberculous) experienced early recurrence and required anterior fusion. In two patients, methylmethacrylate packing was used for spine reconstruction; one of them had a late recurrence. Of the 26 patients with preoperative marked or severe neurological deficit (Frankel Grades A, 2 patients; B, 1 patient; C, 17 patients; and D, 6 patients), 23 (88%) had significant improvement of one grade (15 patients) or more (8 patients). There were no permanent complications. However, intensive care treatment was necessary in 20 of the 26 patients in reduced general condition (mean age, 72 yr). Two patients required further surgery because of postoperative epidural hematoma and pedicle screw malpositioning. In conclusion, most patients with thoracic and lumbar osteomyelitis can be successfully treated by combined débridement and internal fixation using only a posterior approach. Autogenous interbody bone grafting can be simultaneously performed and allows early mobilization of the patient.

Complications of transpedicular screw fixation in the cervical spine

Today, posterior stabilization of the cervical spine is most frequently performed by lateral mass screws or spinous process wiring. These techniques do not always provide sufficient stability, and anterior fusion procedures are added secondarily. Recently, transpedicular screw fixation of the cervical spine has been introduced to provide a one-stage stable posterior fixation. The aim of the present prospective study is to examine if cervical pedicle screw fixation can be done by low risk and to identify potential risk factors associated with this technique. All patients stabilized by cervical transpedicular screw fixation between 1999 and 2002 were included. Cervical disorders included multisegmental degenerative instability with cervical myelopathy in 16 patients, segmental instability caused by rheumatoid arthritis in three, trauma in five and instability caused by infection in two patients. In most cases additional decompression of the spinal cord and bone graft placement were performed. Pre-operative and post-operative CT-scans (2-mm cuts) and plain X-rays served to determine changes in alignment and the position of the screws. Clinical outcome was assessed in all cases. Ninety-four cervical pedicle screws were implanted in 26 patients, most frequently at the C3 (26 screws) and C4 levels (19 screws). Radiologically 66 screws (70%) were placed correctly (maximal breach 1xa0mm) whereas 20 screws (21%) were misplaced with reduction of mechanical strength, slight narrowing of the vertebral artery canal (<25%) or the lateral recess without compression of neural structures. However, these misplacements were asymptomatic in all cases. Another eight screws (9%) had a critical breach. Four of them showed a narrowing of the vertebral artery canal of more then 25%, in all cases without vascular problems. Three screws passed through the intervertebral foramen, causing temporary paresis in one case and a new sensory loss in another. In the latter patient revision surgery was performed. The screw was loosened and had to be corrected. The only statistically significant risk factor was the level of surgery: all critical breaches were seen from C3 to C5. Percutaneous application of the screws reduced the risk for misplacement, although this finding was not statistically significant. There was also a remarkable learning curve. Instrumentation with cervical transpedicular screws results in very stable fixation. However, with the use of new techniques like percutaneous screw application or computerized image guidance there remains a risk for damaging nerve roots or the vertebral artery. This technique should be reserved for highly selected patients with clear indications and to highly experienced spine surgeons.

Preoperative embolization of intracranial meningiomas.

The operative and histopathological findings in 31 cases of intracranial meningioma after preoperative embolization with Gelfoam and/or lyophilized dura mater are reported. Removal of the tumor after embolization was facilitated in those meningiomas fed exclusively or mainly by branches of the external carotid artery (29 of 31). Large areas of tumor necrosis were never seen on histopathological examination, even when suggested by large regions of decreased density on the postembolization computed tomographic scan. Preoperative embolization of the feeding vessels arising from the external carotid artery system has proven to be a useful adjunct before the resection of intracranial meningiomas.

High-resolution ultrasonography in evaluating peripheral nerve entrapment and trauma

High-resolution ultrasonography is a noninvasive, readily applicable imaging modality, capable of depicting real-time static and dynamic morphological information concerning the peripheral nerves and their surrounding tissues. Continuous progress in ultrasonographic technology results in highly improved spatial and contrast resolution. Therefore, nerve imaging is possible to a fascicular level, and most peripheral nerves can now be depicted along their entire anatomical course. An increasing number of publications have evaluated the role of high-resolution ultrasonography in peripheral nerve diseases, especially in peripheral nerve entrapment. Ultrasonography has been shown to be a precious complementary tool for assessing peripheral nerve lesions with respect to their exact location, course, continuity, and extent in traumatic nerve lesions, and for assessing nerve entrapment and tumors. In this article, the authors discuss the basic technical considerations for using ultrasonography in peripheral nerve assessment, and some of the clinical applications are illustrated.

Chronic subdural haematomas treated by enlarged burr-hole craniotomy and closed system drainage. Retrospective study of 120 patients.

SummaryIn a retrospective study 143 chronic subdural haematomas in 120 patients were analysed. 64% of patients were 60 years or older. All haematomas were operated on by slightly enlarged burr-hole craniotomy and closed system drainage for three days postoperatively.A history of trauma was present in 63%. Most frequent symptoms in the older patients were mental changes and impaired consciousness.Postoperative mortality (within one month after surgery) was 4%. After a follow-up period of up to 2.5 years after surgery, 69% were neurologically normal, 20% had only minor complaints or slight deficits. Postoperative CT scans showed a gradual re-expansion of the compressed brain during the 2–3 weeks following haematoma removal.

Findings and long-term results of subsequent operations after failed microvascular decompression for trigeminal neuralgia

OBJECTIVEnTo evaluate the indication of subsequent operations after failed microvascular decompression (MVD) for the treatment of trigeminal neuralgia, the intraoperative findings and long-term results of 16 subsequent operations are reported.nnnMETHODSnSubsequent exploration of the posterior fossa was performed for lack of pain relief (3 patients) and recurrent neuralgia (13 patients) after an average of 17 months (range, 4-62 mo). In all patients, typical arterial compression patterns at the root entry zone of the trigeminal nerve were found in the first procedure. The mean follow-up period after subsequent operation was 90 months (range, 78-104 mo).nnnRESULTSnNew arterial neurovascular conflicts were found in nine patients. After subsequent MVD procedures, seven patients were pain-free (with one recurrence after 6 mo), one had constant marked relief, and one was unchanged. Second exploration revealed no abnormalities in the other seven patients who experienced continued or recurrent pain; only careful neurolysis of the trigeminal nerve was performed in those patients. Initially, all seven patients obtained complete pain relief, but two experienced late recurrences after 64 and 68 months, respectively. Thus, subsequent operations failed in all 4 patients who had undergone prior destructive procedures but were successful in those 12 patients who had undergone only previous MVD. Two patients developed severe sequelae, and the other nine had minor complications, especially permanent (four patients) or transitory (three patients) ipsilateral trigeminal hypoesthesia.nnnCONCLUSIONnSubsequent MVD seems to have good long-term results. However, because of the significantly high incidence of complications, the indication for subsequent operations should be restricted to younger patients to avoid destructive procedures. In general, glycerol rhizolysis or radiofrequency rhizotomy may be the treatment of choice after failed MVD.

Mutation and expression analysis of the KRIT1 gene associated with cerebral cavernous malformations (CCM1)

Abstract. Cavernous malformations are vascular anomalies that can cause severe neurological deficits, seizures and hemorrhagic stroke if these lesions are located in the brain. In patients with cavernomas, constitutional mutations of the KRIT1 gene have been identified. The pathogenetic mechanisms leading to cerebral cavernous malformations (CCM) development are poorly understood. CCM development might be induced in utero owing to the underlying KRIT1 defect, and is triggered by environmental factors. Another model suggests that CCM develop according to the two-hit model of tumorigenesis associated with biallelic inactivation of KRIT1. So far, CCM specimens themselves have not been subjected to mutation analysis. We identified two somatic mutations in the cavernoma of a sporadic case, suggesting that pathogenesis is associated with somatic KRIT1 alterations. To gain a better understanding of the role of KRIT1 during morphogenesis, the main goal of this study was to provide a detailed description of the spatio-temporal expression pattern of Krit1 and its interaction partner Rap1A during mouse embryogenesis. We did not observe enhanced expression of either gene in the heart or large vessels; however, their expression in the developing small vessels or capillaries could not be assessed by the methods applied. At early embryonic stages, Krit1 and, to a lesser extent, Rap1A are expressed in the developing nervous system. During later phases of fetal development, specific expression of both genes is observed in regions of ossification, the dermis, tendons and in the meninges. These findings provide evidence of differential Krit1 and Rap1A expression during mouse ontogenesis and suggest a more widespread functional significance of Krit1, not restricted to vascular endothelial cells.

Cranial neuronavigation with direct integration of (11)C methionine positron emission tomography (PET) data -- results of a pilot study in 32 surgical cases.

Summary.Summary.u2003Background: MRI detects small intracranial lesions, but has difficulties in differentiating between tumour, gliosis and edema. 11C methionine-PET may help to overcome this problem. For its appropriate intra-operative use, it must be integrated into neuronavigation. We present the results of our pilot study with this method.u2003Method: 32 patients with 34 intracranial lesions detected by MRI underwent additional 11C methionine-PET, because the pathophysiological behaviour or the tumour delineation was unclear. All lesions were treated surgically. In 25 patients PET data could be integrated directly into cranial neuronavigation.u2003Findings:11C methionine uptake was observed in 27/34 lesions, 26 of them were tumours: 14 malignant and 7 benign gliomas, 3 gliomas without further histological typing, one Ewing sarcoma and one non-Hodgkin lymphoma. Only one 11C methionine positive lesion was non-tumourous: it was staged as post-irradiation necrosis in a patient operated on for a malignant glioma. 3/7 11C-methionine negative lesions were classified as gliosis (n=2) and M. Whipple (n=1), but 4/7 were tumours: 2 astrocytomas WHO°II, 1 DNT and one astrocytoma WHO°III. The sensitivity of 11C methionine-PET was 87%, the specifity 75%, the positive predictive value 96% and the negative predictive value 43%. In all tumourous cases with positive tracer uptake the borderline area of the tumour was better defined by 11C methionine-PET than by MRI.u2003Interpretation: A positive 11C methionine-PET is highly suspicious of a tumour, a negative one does not exclude it. 11C methionine-PET seems to be more sensitive than MRI for differentiating between tumour and edema or gliosis. Simultaneous integration MRI and 11C methionine-PET into cranial neuronavigation can facilitate cross total tumour removal in glioma surgery.

Selective peripheral denervation for the treatment of spasmodic torticollis

The results of selective peripheral denervation in 50 patients with spasmodic torticollis are presented. Of our patients, 76% reported a significant improvement or disappearance of their dystonia. The mean follow-up is 25 months. There were no major side effects. We recommend the procedure to patients who primarily have responded to botulinum toxin therapy and had become secondary nonresponders or to those refusing further injections while still responding. The results are much less promising in patients who are primary nonresponders to botulinum toxin. Some remarkable histological findings are presented. The posterior branches of the cervical roots frequently showed signs of severe compression neuropathy. In three cases, a functional motor nerve regeneration was proved. Among all surgical options, selective peripheral denervation provides the best result and has the fewest side effects.

The influence of prophylactic vasoactive treatment on cochlear and facial nerve functions after vestibular schwannoma surgery: a prospective and open-label randomized pilot study.

OBJECTIVE Facial nerve paresis and hearing loss are common complications after vestibular schwannoma surgery. Experiments with facial nerves of the rat and retrospectively analyzed clinical studies showed a beneficial effect of vasoactive treatment on the preservation of facial and cochlear nerve functions. This prospective and open-label randomized pilot study is the first study of a prophylactic vasoactive treatment in vestibular schwannoma surgery. METHODS Thirty patients were randomized before surgery. One group (n = 14) received a vasoactive prophylaxis consisting of nimodipine and hydroxyethylstarch which was started the day before surgery and was continued until the seventh postoperative day. The other group (n = 16) did not receive preoperative medication. Intraoperative monitoring, including acoustic evoked potentials and continuous facial electromyelograms, was applied to all patients. However, when electrophysiological signs of a deterioration of facial or cochlear nerve function were detected in the group of patients without medication, vasoactive treatment was started immediately. Cochlear and facial nerve function were documented preoperatively, during the first 7 days postoperatively, and again after long-term observation. RESULTS Despite the limited number of patients, our results were significant using the Fishers exact test (small no. of patients) for a better outcome after vestibular schwannoma surgery for both hearing (P = 0.041) and facial nerve (P = 0.045) preservation in the group of patients who received a prophylactic vasoactive treatment. CONCLUSION Prophylactic vasoactive treatment consisting of nimodipine and hydroxyethylstarch shows significantly better results concerning preservation of the facial and cochlear nerve function in vestibular schwannoma surgery. The prophylactic use is also superior to intraoperative vasoactive treatment.