Gerhard Marquardt

Clinical application of proton magnetic resonance spectroscopy in the diagnosis of intracranial mass lesions

Diagnosis of primary and secondary brain tumours and other focal intracranial mass lesions based on imaging procedures alone is still a challenging problem. Proton magnetic resonance spectroscopy (1H-MRS) gives completely different information related to cell membrane proliferation, neuronal damage, energy metabolism and necrotic transformation of brain or tumour tissues. Our purpose was to evaluate the clinical utility of 1H-MRS added to MRI for the differentiation of intracranial neoplastic and non-neoplastic mass lesions. 176 mostly histologically verified lesions were studied with a constant clinically available single volume 1H-MRS protocol following routine MRI. 12 spectra (6.8%) were not of satisfactory diagnostic quality; 164 spectroscopic data sets were therefore available for definitive evaluation. Our study shows that spectroscopy added to MRI helps in tissue characterization of intracranial mass lesions, thereby leading to an improved diagnosis of focal brain disease. Non-neoplastic lesions such as cerebral infarctions and brain abscesses are marked by decreases in choline (Cho), creatine (Cr) and N-acetyl-aspartate (NAA), while tumours generally have elevated Cho and decreased levels of Cr and NAA. Gliomas exhibit significantly increased Cho and lipid formation with higher WHO tumour grading. Metastases have elevated Cho similar to anaplastic astrocytomas, but can be differentiated from high-grade gliomas by their higher lipid levels. Extra-axial tumours, i.e. meningiomas and neurinomas, are characterized by a nearly complete absence of the neuronal marker NAA. The additive information of 1H-MRS led to a 15.4%-higher number of correct diagnoses, to 6.2% fewer incorrect and 16% fewer equivocal diagnoses than with structural MRI data alone.

Feasibility of Polestar N20, an ultra-low-field intraoperative magnetic resonance imaging system in resection control of pituitary macroadenomas: lessons learned from the first 40 cases.

OBJECTIVETo evaluate the feasibility of PoleStar N20 (Medtronic Surgical Navigation Technologies, Louisville, KY), an ultra-low-field intraoperative magnetic resonance imaging (iMRI) system during resection control of pituitary macroadenomas and to compare intraoperative images with postoperative 1.5-T MRI images obtained 3 months after the procedure. METHODSForty patients with a pituitary macroadenoma (mean size, 26.9 ± 9.1 mm) underwent a surgical procedure to remove the tumor. The iMRI system was implemented in a standardized microsurgical procedure (endonasal, transseptal, transsphenoidal approach) using standard microsurgical instruments. Intraoperative imaging was performed for tumor visualization/navigation and resection control. If an accessible tumor remnant was suspected, surgery was continued for reexploration and, if necessary, continued resection. Total anesthesia time and operation time were compared with a historical cohort of 100 patients who underwent a surgical procedure on pituitary adenomas without iMRI. Sensitivity and specificity of the iMRI to detect residual tumor tissue was assessed in 33 patients (82.5%) after comparison with standard postoperative 1.5-T MRI 3 months after the procedure. RESULTSPreoperative tumor visualization with the ultra-low-field iMRI showed a very good congruency with the preoperative 1.5-T MRI scans. A three-dimensional reconstruction of the coronal scan enabled the surgeon to safely approach the tumor using the integrated navigation system. In seven patients (17.5%), iMRI resection control showed accessible residual tumors leading to further resection. After tumor resection, the final iMRI scan documented adequate decompression of the optic pathway in all patients. Implementation of iMRI led to a significant increase of anesthesia time (246.0 ± 50.7 versus 163.4 ± 41.2 min) and operation time (116.9 ± 43.9 versus 78.2 ± 33.0 min; P < 0.05, t test). Sensitivity of the iMRI was 88.9, 85.7, 93.3, and 100% for the suprasellar, intrasellar, and right and left parasellar regions, respectively, and the specificity was 90.5% in the suprasellar and 100% in the intra- and parasellar regions on both sides. In four patients, the intraoperative interpretation of iMRI was equivocal; thus, it was difficult to distinguish between very small tumor remnants and perioperative changes. CONCLUSIONUltra-low-field 0.15-T iMRI is a safe, helpful, and feasible tool for navigation and tumor resection control in patients with pituitary macroadenomas. Total anesthesia and operation times are prolonged, but iMRI adequately documents the extent of tumor resection. In this series, the PoleStar system increased the rate of resection without disrupting the neurosurgical workflow.

Management of spinal meningiomas: surgical results and a review of the literature

OBJECT In this report, the authors describe their experience in the surgical management of spinal meningiomas at two neurosurgical centers. The results of a literature review are also presented. METHODS Eighty consecutive patients (22 men and 58 women) with spinal meningiomas who had undergone an operation at two specific neurosurgical centers were included in this study. Functional outcomes were evaluated using univariate and multivariate analyses. A review of the literature yielded an additional 651 patients with spinal meningiomas from 9 large studies. RESULTS On multivariate analysis, the variable of a poor preoperative neurological state (p < 0.02, odds ratio [OR] 13.6, 95% confidence interval [CI] 2.6-71.4) and invasion of the arachnoid/pia mater (p < 0.03, OR 15.2, 95% CI 2.5-90.4) were independent predictors of a poor outcome, whereas invasion of the arachnoid/pia (p < 0.02, OR 8.9, 95% CI 2.2-35) and duration of symptoms (p < 0.001, OR 1.12/month, 95% CI 1.05-1.2) predicted no improvement (stable or deteriorated condition). The Cox proportional hazards regression analysis showed three significant predictor variables for recurrence: invasion of the arachnoid/pia (p < 0.05; hazard ratio [HR] 1.8, 95% CI 1.2-3.6), Simpson resection grade (p < 0.012, HR 6.8, 95% CI 1.5-3.0), and histological tumor grade (Grade I; p < 0.001, HR 0.001-0.17). CONCLUSIONS Because of the excellent outcome of surgery for benign spinal meningiomas and the association between duration of symptoms and neurological compromise with a poor functional outcome, early operation is the treatment of choice. In cases of malignant transformation, adjuvant therapies must be considered.

Changes in cervical spine curvature after uninstrumented one- and two-level corpectomy in patients with spondylotic myelopathy.

OBJECTIVEWe studied changes in the cervical spine curvature in patients with cervical spondylotic myelopathy who underwent one- or two-level central corpectomy and iliac bone grafting without the use of instrumentation. METHODSCurvature of the fused segment and of the whole cervical spine was evaluated on preoperative and follow-up x-rays in 93 patients (30 underwent one-level corpectomy, and 63 underwent two-level corpectomy). In 59 patients, the changes in the cervical spine curvature were studied using one follow-up x-ray; in the other 34 patients, the changes were studied on x-rays obtained at two or more follow-up visits. The sagittal alignment of the fused segment was categorized as lordotic (>+5 degrees), straight (+5 to −5 degrees) or kyphotic (>−5 degrees). The whole spine curvature also was recorded as lordotic, straight, or kyphotic. RESULTSAt a mean follow-up of 22.2 months (range, 6–71 mo), there was a mean change of −10.4 degrees in the segmental curvature (P < 0.001). The fused segment sagittal alignment also worsened (lordotic angles becoming straight or kyphotic and straight angles becoming kyphotic) in 44 patients (47%)(P < 0.001). However, serial studies in 34 patients (mean first and last follow-ups, 11.9 and 30.8 mo, respectively) did not demonstrate significant worsening of the kyphotic angle or the sagittal alignment over time (P = 0.9). Whole spine curvature worsened in 33 (35%) of the 93 patients (P < 0.001); serial studies did not reveal a significant change (P = 0.9). Patients improved in their functional status from a preoperative mean Nurick grade of 2.9 (range, 1–5) to a follow-up mean Nurick grade of 1.5 (range, 0–4) (P < 0.001). Patients with a kyphotic change in their whole spine curvature (n = 33) and those without such change (n = 60) had a similar functional outcome (mean change in Nurick grade, 1.5 and 1.4, respectively). CONCLUSIONCervical spine curvature tended to undergo a kyphotic change at the fused segment in 47% of patients and a kyphotic change of the whole spine curvature in 35% of patients who underwent one- or two-level uninstrumented central corpectomy. This kyphotic change in the cervical spine, which stabilizes within 1 year after surgery, is not progressive, and it does not affect neurological outcome in these patients.

Intradural and extradural spinal metastases

Abstract Intradural spinal metastases are uncommon. The outcome of surgical treatment of intra- and extramedullary intradural metastases is considered to be poor, with rapid clinical deterioration. The question of optimal treatment remains controversial. We present an overview of the clinical outcome and surgical treatment of 220 spinal metastases carried out in our centre from 1980 to 1999, with particular emphasis on 11 intradural metastases. Clinical history, signs, surgical approach, outcome, and radiological reports were obtained by review of patient charts. Secondary spinal tumours most often originated from carcinomas of the breast, lung, kidney, gastrointestinal tract, and prostate. In 12% of cases, no primary tumour could be found. Drop metastases of intracranial pathology appeared in 3%. Intradural metastases were seen in 11 patients and formed a very heterogeneous group with predominance of melanoma, lymphoma, and medulloblastoma. Functional recovery and survival time were worse in intradural metastases than in extradural metastases, and the patients were younger. Treatment of metastases is designed to relieve pain and preserve or restore neurological function palliatively. Intradural metastases are a devastating condition with usually fatal outcome. Selected patients who undergo aggressive surgical treatment may have substantially increased survival.

Bone Flap Resorption: Risk Factors for the Development of a Long-Term Complication following Cranioplasty after Decompressive Craniectomy

Aseptic bone flap resorption (BFR) is a known long-term complication after cranioplasty (CP). We analyzed our institutional data in order to identify risk factors for BFR. From October 1999 to April 2012, 254 patients underwent CP after decompressive craniectomy (DC) at our institution, and had a long-term follow-up period of >1 year after CP (range 12-146 months). Overall, BFR occurred in 10 of 254 patients as a long-term complication after CP (4%). BFR developed more often in patients aged ≤18 years (p=0.008), in patients who previously underwent DC for traumatic brain injury (p=0.04), and in patients with multiple fractures within the reinserted bone flap (p=0.002). Furthermore, BFR developed significantly more often in patients who underwent cranioplasty ≤2 months after DC (p=0.008), as well as in patients with wound healing disturbance or abscess as an early complication after the CP procedure (p=0.01). The multivariate analysis of the present data identified the presence of multiple fractures within the bone flap (p=0.002, OR 10.3, 95% CI 2.4-43.8), wound infection after CP (p=0.003, OR 12.3, 95% CI 2.3-65.3), and cranioplasty performed ≤2 months after DC (p=0.01, OR 6.3, 95% CI 1.5-26.3) as independent risk factors for the development of BFR after CP in a large series with long-term follow-up. This might influence future surgical decision making, especially in patients fulfilling high risk criteria for developing BFR.

Long term follow up after perimesencephalic subarachnoid haemorrhage

OBJECTIVES To evaluate the long term sequelae of perimesencephalic subarachnoid haemorrhage (PMSAH). METHODS Twenty one consecutive patients were studied. All patients were examined by CT, angiography, MRI, multimodal evoked potentials, and transcranial Doppler sonography. All relevant clinical data during hospital stay and outcome at discharge were obtained by reviewing the charts. Long term follow up was evaluated by reviewing the outpatient files and dedicated outpatient review. Patients were specifically questioned about their perceived recovery, residual complaints, and present occupational status. RESULTS Apart from the initial CT confirming the diagnosis of PMSAH all other examinations disclosed no abnormalities. None of the patients developed any complications during hospital stay, and all patients were discharged in good clinical condition and without neurological deficits. At long term follow up 62% of the patients had residual complaints consisting of headaches, irritability, depression, forgetfulness, weariness, and diminished endurance. Apart from four patients who had already retired before the PMSAH, only seven of the remaining 17 patients (41%) returned to their previous occupation, whereas nine patients (53%) retired from work and one man became unemployed. One patient had a recurrence of PMSAH 31 months after the first event. CONCLUSION PMSAH can have considerable long term psychosocial sequelae, and may also recur. Prognosis may not be as good as previously reported.

Diffusion tensor imaging tractography in patients with intramedullary tumors: comparison with intraoperative findings and value for prediction of tumor resectability

OBJECT The aim of this retrospective study was to evaluate the predictive value of diffusion tensor (DT) imaging with respect to resectability of intramedullary spinal cord tumors and to determine the concordance of this method with intraoperative surgical findings. METHODS Diffusion tensor imaging was performed in 14 patients with intramedullary lesions of the spinal cord at different levels using a 3-T magnet. Routine MR imaging scans were also obtained, including unenhanced and enhanced T1-weighted images and T2-weighted images. Patients were classified according to the fiber course with respect to the lesion and their lesions were rated as resectable or nonresectable. These results were compared with the surgical findings (existence vs absence of cleavage plane). The interrater reliability was calculated using the kappa coefficient of Cohen. RESULTS Of the 14 patients (7 male, 7 female; mean age 49.2 +/- 15.5 years), 13 had tumors (8 ependymomas, 2 lymphomas, and 3 astrocytoma). One lesion was proven to be a multiple sclerosis plaque during further diagnostic workup. The lesions could be classified into 3 types according to the fiber course. In Type 1 (5 cases) fibers did not pass through the solid lesion. In Type 2 (3 cases) some fibers crossed the lesion, but most of the lesion volume did not contain fibers. In Type 3 (6 cases) the fibers were completely encased by tumor. Based on these results, 6 tumors were considered resectable, 7 were not. During surgery, 7 tumors showed a good cleavage plane, 6 did not. The interrater reliability (Cohen kappa) was calculated as 0.83 (p < 0.003), which is considered to represent substantial agreement. The mean duration of follow-up was 12.0 +/- 2.9. The median McCormick grade at the end of follow-up was II. CONCLUSIONS These preliminary data suggest that DT imaging in patients with spinal cord tumors is capable of predicting the resectability of the lesion. A further prospective study is needed to confirm these results and any effect on patient outcome.

Cerebellar hemorrhage after supratentorial craniotomy.

BACKGROUND Cerebellar hemorrhage following supratentorial craniotomy is a very seldom described but serious complication. The present study evaluates the significance of presurgical and surgical factors that may predispose patients to these bleeding episodes. METHODS The data of 52 cases of cerebellar hemorrhage following supratentorial craniotomy, 9 from our records and 43 from the literature, were analyzed with regard to various variables. RESULTS The findings suggest that this clinical picture is unrelated to age, previous arterial hypertension, inherent or induced coagulopathies, type of primary underlying lesion, intraoperative positioning of the patient, type of anesthesia, or intracranial hypotension and its sequels. It entails significant morbidity, with one third of the patients left with cerebellar dysfunction or in a dependent state, and carries a mortality of about 25%. CONCLUSION Not one single presurgical or surgical factor can reliably predict the occurrence of cerebellar hemorrhage after supratentorial craniotomy, and the etiology of this entity still remains unclear. The most important keys to minimize the hazardous sequelae are to be aware of this potential complication and to diagnose it early.

Spontaneous haematoma of the iliac psoas muscle: a case report and review of the literature.

Abstract. Spontaneous haematomas of the iliac psoas muscle are rare lesions seen in patients receiving anticoagulant agents or suffering from clotting disorders. We report the rare case of a spontaneous iliac psoas haematoma causing femoral neuropathy in a patient not undergoing anticoagulant treatment or suffering from a coagulopathy. After conservative treatment the patient was entirely asymptomatic, and magnetic resonance imaging demonstrated complete dissolution of the haematoma. Spontaneous iliac psoas haematomas should be considered in the differential diagnosis of leg pain in otherwise healthy patients.