Papers by Maximilian Mehdorn
Cerebellar Infarct. Midline Tumors. Minimally Invasive Endoscopic Neurosurgery (MIEN), 1994
The routine use of microneurosurgical techniques has dramatically reduced the peri- and postopera... more The routine use of microneurosurgical techniques has dramatically reduced the peri- and postoperative morbidity and mortality of patients harboring an arteriovenous malformation (AVM) of the brain [6, 18]. However, AVMs located in speech or deep areas of the brain or with a large size and/or high blood flow through the AVM nidus still represent a formidable challenge for the treating neurosurgeon. Stereotactic proton beam radiosurgery has been advocated for the treatment of AVMs of the brain that are considered to be of high surgical risk either due to their location in speech or deep areas of the brain or to their size [3, 4]. Because of excellent results of proton beam radiosurgery reported in the literature in the early 1980s [3], a group of 68 patients harboring high-risk cerebral AVMs were referred from our Department to a major radiosurgical center in the United States over a period of 10 years. However, intermediate and long-term follow-up revealed that in the vast majority of these patients the dimension of the AVM after radiation therapy remained virtually unchanged [11]. Additionally, the clinical symptoms present prior to radiation therapy did not show amelioration after radiosurgery in more than half of the patients, while deterioration due to hemorrhage from the radiated AVM, increased seizure frequency, progressive neurological deficits or as the result of radiation-induced leukencephalopathy developed in a considerable percentage of the patients.
Objective: Intradural disc herniation is a rare condition. An incidence of intradural disc hernia... more Objective: Intradural disc herniation is a rare condition. An incidence of intradural disc herniation in between 0,26 -0,30% of all herniated discs has been reported. Only 3% of all intradural disc herniation are found in the cervical region. Adhesion between dura sac and posterior longitudinal[for full text, please go to the a.m. URL]
Acta neurochirurgica. Supplement, 2002
The clinical results of surgery for unruptured aneurysms in the Neurosurgical Department of Kiel ... more The clinical results of surgery for unruptured aneurysms in the Neurosurgical Department of Kiel were analyzed to further discuss whether an operative treatment can be advised. Between 1991 and 2001, 54 unruptured aneurysms in 45 patients were operated in our department. No complications occurred in 38 patients; transient complications (slight aphasia, hemiparesis, psychiatric disorders) in 4 patients; postoperative seizures in one, epidural haematoma with the need of re-operation in one, and infection in another patient. At the time of discharge, GOS was 5 in 33 patients, 4 in 12 patients. But the slight disabilities were due to the aneurysm operation only in two patients, in the other 10 patients they were caused by pre-existing concomitant diseases. The Rankin-Scale after at least 6 months was 1 (no disability) in 31 patients (37 patients investigated); 2 (slight disability) in 5, and 3 (moderate disability) in one patient. In only one of these patients, the slight disability was...
Journal of Neurology Research, 2011
We present a rare case of rapid growing intramuscular myxoma mimicking a peripheral nerve sheath ... more We present a rare case of rapid growing intramuscular myxoma mimicking a peripheral nerve sheath tumor (PNST). During diagnostic investigations for abdominal pain in a 65-year-old female patient a 5.5 cm diameter tumor in the left buttock was found incidentally. The tumor was septated and hyperintense in the T2weighted images in the left gluteal region, adjacent to the sciatic nerve, presumed to be a PNST. The follow up images four months later showed marked gain of the tumor size. The tumor has been resected completely and histopathological examination revealed the diagnosis of an intramuscular myxoma. As an uncommon benign tumor, intramuscular myxoma presented very suspiciously for a PNST because of direct adjacency to the sciatic nerve with an increased growth tendency. Despite the benign entity of intramuscular myxoma surgical treatment was indicated because of the rapid growth and unclear circumstances with the possibility of malignant behavior.
Clinical Neurology and Neurosurgery, 2016
Awake craniotomy is a well-established procedure in surgery of intracranial tumors in eloquent ar... more Awake craniotomy is a well-established procedure in surgery of intracranial tumors in eloquent areas. However, sufficiently standardized instruments for the assessment of sensory-motor function before, during and after the operation are currently lacking, despite their importance for evaluation of operative outcome. To address this issue, we designed a standardized assessment tool (the "sensory-motor profile awake scale"; SMP-a). The final scale consists of three motor sections (face, arm and leg) assessing both gross and fine motor skills and one sensory section. It differentiates between six grades of impairment and its tasks are applicable for intraoperative continuous monitoring of sensory-motor functions and supporting processes. We analyzed the data of 17 patients with intracranial tumors eligible for awake craniotomy who were preoperatively assessed with the SMP-a. In addition, we present an exemplary case. Our data support the assumption that the SMP-a is feasible in patients eligible for awake craniotomy, even in patients with symptoms of mild aphasia or more severe sensory-motor deficits caused by tumor recurrence. The exemplary case demonstrates the feasibility of repeated measures with the SMP-a in a tumor patient, including the adaption of tasks to the individual requirements of an intraoperative setting. This exploratory study suggests that the SMP-a might be a feasible rating scale in patients with intracranial tumors. The flexibility of the scale enables individual adaption, but preserves the standardized scoring system to allow comparison between assessment dates, patients and, hopefully in the future, institutions. However, future studies are mandatory to provide data on the instrument's diagnostic properties with respect to feasibility, objectivity, validity and reliability.
Journal of neurosurgical sciences, Jan 15, 2016
Deep brain stimulation (DBS) has become one of the major therapy options for movement disorders i... more Deep brain stimulation (DBS) has become one of the major therapy options for movement disorders including dystonia. This article should give a review of the current literature from a neurosurgical perspective. Since dystonia is a rare disease, only few studies on larger cohorts have been published, and very few randomized controlled studies are avaialable in the international literature. Our experiences gained treating 134 patients with various types of dystonia, between 1999 and 2015, will serve a guide to interpret the current literature. Symptoms of dystonia are due to a variety of medical conditions. A careful and extensive neurological evaluation is mandatory before medical and surgical treatment options are considered, since the clinical benefits of more aggressive treatment e.g. by DBS depend to a large extent on the etiology of the disease. Diagnostic steps should include also Magnetic resonance imaging (MRI) and possibly genetic evaluation. Therapy consist of physiotherapy,...
Medical Imaging 1999: PACS Design and Evaluation: Engineering and Clinical Issues, 1999
ABSTRACT In medical image processing original image data on archive servers may absolutely not be... more ABSTRACT In medical image processing original image data on archive servers may absolutely not be modified directly. On the other hand, images from read-only devices like CD-ROM cannot be changed and saved on the same storage medium. In both cases the modified data have to be stored as a second version and large amounts of storage volume are needed. We avoid these problems by using a program which records only each transaction prescribed to images. Each transaction is stored and used for further utilization and for renewed submission of the modified data. Conventionally, every time an image is viewed or printed, the modified version has to be saved in addition to the recorded data, either automatically or by the user. Compared to these approaches which not only squander storage space but area also time consuming our program has the following and advantages: First, the original image data which may not be modified are protected against manipulation. Second, small amounts of storage volume and network range are needed. Third, approved image operations can be automated by macros derived from transaction recordings. Finally, operations on the original data can always be controlled and traced back. As the handling of images gets easier with this concept, security for original image data is granted.
Brain stimulation
Within the last years, occipital nerve stimulation (ONS) has proven to be an important method in ... more Within the last years, occipital nerve stimulation (ONS) has proven to be an important method in the treatment of severe therapy-resistant neurological pain disorders. The correspondence between lead placement as well as possible stimulation parameters and the resulting stimulation effects remains unclear. The method aims to directly relate the neuromodulatory mechanisms with the clinical treatment results, to achieve insight in the mode of action of neuromodulation, to identify the most effective stimulation sets and to optimize individual treatment effects. We describe a new computer-based imaging method for mapping the spatial, cognitive and affective sensory effects of ONS. The procedure allows a quantitative and qualitative analysis of the relationship between lead positioning, the stimulation settings as well as the sensory and clinical stimulation effects. A regular mapping of stimulation and sensory parameters allows a coordinated monitoring. The stimulation results can be r...
Journal of Neuro-Oncology, 2014
To the Editor, A 60 year old man presented with acute visual impairment. The patient reported res... more To the Editor, A 60 year old man presented with acute visual impairment. The patient reported restricted libido for years and a history of migraine headache. An immunosuppressive disease was not known. Neurological examination revealed acute loss of visual acuity on the right side and a right lateral visual-field defect. Cranial computed tomography (CT) and magnetic resonance imaging (MRI) showed pituitary adenoma with intratumoral bleeding and consecutive compression of the optic chiasm (Fig. ; arrows). Additionally, mucosal swelling -or possibly tumor extension-was noticed within the sphenoid sinus (Fig. ). Hormonal analysis showed a deficit of thyroid-stimulating hormone (TSH), cortisol and testosterone. Replacement therapy with l-thyroxine, hydrocortisone and testosterone was initiated. The patient underwent emergency evacuation of the adenoma and the hematoma via a microsurgical transsphenoidaltransnasal approach. Herein, the bony sella floor was found very thin but intact. Mucosal swelling-which was removed-turned out to be an incidental aspergilloma. Dural plasty was performed with layers of TACHOSIL Ò , bone fragments, fibrin glue and TABOTAMP Ò . Histological
Supportive Care in Cancer, 2012
The aim of this study was to provide the first prospective longitudinal assessment of anxiety and... more The aim of this study was to provide the first prospective longitudinal assessment of anxiety and depression in patients with a benign intracranial meningioma (WHO° I). The Hospital Anxiety and Depression Scale was applied prior to (t1) and directly after (t2) neurosurgery as well as 6 months after surgery (t3). The research was conducted in a single treatment centre in Germany. Numerous sociodemographic, medical, psychological and cognitive accompanying measures were assessed. The study population consisted of 52 meningioma patients. Additionally, a control group of 24 patients with malignant brain tumours (astrocytoma WHO° III) was assessed. In meningioma patients, anxiety was high prior to surgery but declined significantly after successful neurosurgical treatment. Low levels of depression were observed at all times. In contrast, astrocytoma patients showed constantly high levels of anxiety whilst depression increased over the course of the disease. Numerous medical, psychosocial and psychological factors were associated with psychiatric morbidity in meningioma patients. In conclusion, psychiatric morbidity of patients with benign intracranial meningiomas was comparable to that of the general population after successful neurosurgical treatment. Numerous associated factors suggest complex relationships within a biopsychosocial model. However, due to the small sample size and recruitment in a single institution, our results are of limited generalisability and need cross-validation in future studies.
Neurosurgical Review, 1991
In order to better define patients who might benefit from cerebral revascularization surgery, tra... more In order to better define patients who might benefit from cerebral revascularization surgery, transcranial Doppler sonography was used in more than 480 patients. Thus invasive diagnostic studies could be limited to probable surgical candidates. Transcranial Doppler sonography has proven to be reliable for the study of the degree of efficacy of intracranial collateral pathways in hemodynamic borderline situations. Over the last 4 years, the application of the algorythm presented in this paper resulted in a reduction of the number of candidates for surgical revascularization to 19.
Neurosurgery, 1986
We present a patient with internal carotid artery occlusion and ischemic oculopathy in whom extra... more We present a patient with internal carotid artery occlusion and ischemic oculopathy in whom extracranial-intracranial arterial bypass improved vision. Visual evoked potentials were studied to obtain objective criteria for indication and follow-up evaluation and confirmed that the improved vision was due to improved retinal function. (Neurosurgery 19:1031-1034, 1986)
Neuroradiology, 2001
Granular-cell tumour is a rare suprasellar space occupying lesion, which usually presents with vi... more Granular-cell tumour is a rare suprasellar space occupying lesion, which usually presents with visual deterioration, endocrine deficits or headache. We present two women with extraordinarily large tumours, measuring 3.8 and 4.0 cm in diameter. In both cases the tough, vascular tumour could be removed only subtotally.
Neurological Research, 2003
Intracerebral hemorrhage (ICH) occurs in about 10%-15% of all strokes, and hypertension and cereb... more Intracerebral hemorrhage (ICH) occurs in about 10%-15% of all strokes, and hypertension and cerebral amyloid angiopathy (CAA) are the main underlying causes. There is often controversy regarding surgical evacuation especially in elderly patients. Follow-up of these patients and regulation of hypertension is important to prevent re-bleeding. The number of recurrent hematomas will increase with time of follow-up. We reviewed 968 patients with an ICH treated in our Department and 48 patients with recurrent hemorrhages (4.9%). The mean interval between the rst and the second hemorrhage was three years (one month to 10 years). Clinical outcome after a second hemorrhage was severe and only 50% of patients were operated on the second hemorrhage compared to 77% (37/48) of patients who were operated on the rst hemorrhage.
Neurological Research, 2005
Vascular endothelial growth factor (VEGF) and its receptors VEGFR-1 and -2 are considered to play... more Vascular endothelial growth factor (VEGF) and its receptors VEGFR-1 and -2 are considered to play a major in tumor angiogenesis, which is a prerequisite for growth of solid tumors. Glioblastoma multiforme is a prominent example of VEGF-induced tumor vascularization; however, little is known about VEGF and in particular VEGFR expression in other types of brain tumors. VEGFR mRNA was quantified by real time RT-PCR in 12 different types of brain tumors and compared to VEGF protein content measured by ELISA. VEGF splice variants were determined by an RT-PCR method. VEGF protein was highest in glioblastoma and metastatic kidney tumors. In all types of tumors the diffusible splice forms VEGF(121) and VEGF(165) were expressed; VEGF(189) was minor in a few tumors. Expression of VEGF receptors did not necessarily correlate with VEGF content. Both were highly expressed in glioblastomas, but in meningiomas VEGF was low and VEGFR high, and in metastatic tumors the reverse. With few exceptions, in particular oligodendrogliomas, VEGFR-1 expression was parallel to VEGFR-2 expression. Interestingly, for the astrocytic gliomas, the expression of VEGFR correlated well to the tumor malignancy, even better than VEGF content. These results show that VEGF and VEGFR expression in various types of brain tumors differ and are not necessarily parallel.
Journal of Neurosurgical Anesthesiology, 2011
Background: Preoperative anxiety is a major problem in patients with brain tumors and is of high ... more Background: Preoperative anxiety is a major problem in patients with brain tumors and is of high clinical relevance. However, to date no instruments have been validated for the assessment of preoperative anxiety for this patient group. The Amsterdam Preoperative Anxiety and Information Scale (APAIS) has shown promising results for the assessment of preoperative anxiety. The aim of this study was to determine its psychometric properties and the optimal cutoff score for patients with intracranial tumors to make it applicable in the neurosurgical setting. The sample totaled 180 neurosurgical patients with intracranial tumors. Patients were administered the APAIS along with the Hospital Anxiety and Depression Scale as the gold standard against which the APAIS was compared. Patients scoring 11 or above in the anxiety subscale of the Hospital Anxiety and Depression Scale were defined as clinical cases having anxiety. The psychometric properties of the APAIS were evaluated for a postulated 2-factor structure, Cronbach a, and correlations. The postulated 2-factor structure could not be replicated. Instead, we found a 3-factor solution (anxiety about the operation, anxiety about the anesthesia, information requirement). The area under the receiver operating characteristics curve ranged from Z0.65 to Z0.77. Optimal cutoff scores were calculated. The cutoff score for the anxiety scale was Z10 for the whole sample and men only, and was Z11 for women only. Analysis of the psychometric properties yielded satisfactory results (eg. Cronbach a for the anxiety scale >0.84). Conclusions: Despite its brevity, the APAIS is valid and recommendable for the assessment of preoperative anxiety in patients with intracranial tumors. As this is the first validation study focusing on patients with severe diseases and major surgeries, we recommend the application of our cutoff scores also for patients similar to our study population with regard to disease and surgery severity.
Journal of Neurosurgery, 1994
✓ Within a period of nearly 10 years, from October, 1980, to May, 1990, a total of 68 patients wi... more ✓ Within a period of nearly 10 years, from October, 1980, to May, 1990, a total of 68 patients with a cerebral arteriovenous malformation (AVM) were referred to a radiosurgical center in the United States for stereotactic Bragg peak proton beam therapy. Radiosurgery was chosen as an alternative treatment, either because the AVM was considered to be of high surgical risk due to its size and/or location, or because the patient refused surgery. In 63 patients (92.6%), complete clinical and radiological follow-up examinations were available. Clinical and radiological long-term results were correlated to size and to the Spetzler-Martin scale of the AVM. With increasing size or higher grade on the Spetzler-Martin scale, the clinical results of proton beam therapy became progressively worse. Of 37 patients with an AVM between 3 and 6 cm in diameter, only one-third showed amelioration of their clinical symptoms, and two-thirds remained the same or even deteriorated after radiation treatment...
Journal of Neuro-Oncology, 2004
We present a very rare case of an intracranial ganglioneurocytoma. This 57-year-old female patien... more We present a very rare case of an intracranial ganglioneurocytoma. This 57-year-old female patient noticed some concentration difficulties for about 5 months. Visual acuity was 80% on both sides. CT and MRI of her head demonstrated a 3 × 2.5 × 2.8 cm 3 lesion within the third ventricle with inhomogenous enhancement of contrast medium. After a right pterional approach the tumor could be removed completely. Postoperatively there was a paresis of the oculomotor nerve on the right side and psychological changes. Histological examination revealed neuronal differentiation with neurocytes and small ganglionic cells and the tumor was graded as a ganglioneurocytoma (WHO grade II). Follow-up examination 6 months after the operation showed improvement of her third nerve paresis and of her neuropsychological deficits. MRI showed no recurrence.
European Journal of Pharmacology, 1989
Radioligand binding studies suggest that cq-adrenoceptor recognition sites are heterogeneous. Sev... more Radioligand binding studies suggest that cq-adrenoceptor recognition sites are heterogeneous. Several adrenergic agents discriminate between two adrenoceptor binding sites designated alA and c~aB. In the present study we demonstrate for the first time that these two subtypes exist in the human brain. 5-Methyl-urapidil and (+)-niguldipine, which have previously been shown to be CqA-selective, inhibited [3H]prazosin binding to cortical membranes in a biphasic manner. The irreversible C~lB-ligand , chloroethylclonidine, preferentially eliminated the binding sites with low affinity for (+)-niguldipine. In contrast, BE 2254 and unlabelled prazosin displaced the radioligand in a monophasic manner. The ICs0 values for prazosin were not affected by pretreatment of the membranes with chloroethylclonidine. Our data on human brain membranes are in excellent agreement with recent findings in rat tissues and suggest that the c~-adrenoceptor subtypes in human brain are similar to those in rat tissues.
Current Medical Research and Opinion, 2008
BACKGROUND: Gliomas account for 42% of all primary CNS neoplasms and 77% of all malignant primary... more BACKGROUND: Gliomas account for 42% of all primary CNS neoplasms and 77% of all malignant primary CNS neoplasms. Unfortunately the high-grade variant of gliomas, glioblastoma multiforme (GBM), is difficult to treat and generally considered incurable. Survival rates are generally poor, and neurological morbidity in the setting of disease progression is high. Fortunately, significant progress has been achieved in the past decade in our understanding of the molecular biology of this aggressive tumour histology and, as a consequence, there is renewed clinical trial activity in this area focused on improving quality of life, treatment-related morbidity and outcomes. METHODS: A review of literature from June 2005 to June 2008 was conducted on multimodal treatment of malignant glioma (MG) patients, using specific search criteria in Medline, EMBASE, and BIOSIS. Abstracts from relevant US and European medical (cancer) meetings were also evaluated. RESULTS: The established therapies for MG include surgery, radiotherapy (RT), and local or systemic chemotherapy. However, over the last 10 years only two chemotherapeutic agents have received regulatory approval for treatment of MG: polifeprosan 20 with carmustine (BCNU implant) and temozolomide (TMZ), an imidazotetrazine derivative of dacarbazine. More recent advances in the treatment of brain tumours have been in the development of multimodal approaches. Specific interest in the combination of BCNU implant and TMZ has arisen due to the demonstrable depletion by TMZ of the DNA repair enzyme responsible for resistance to a nitrosourea such as BCNU. Further interest in this combination stems from the observation that there is a difference in the time to peak effect for each agent. Additional emerging data suggest that multimodal therapy with maximal resection and BCNU implants, followed by adjuvant therapy with radiation and TMZ, is effective and well-tolerated in patients with initial high-grade, resectable MG. CONCLUSIONS: The increasing body of efficacy data suggests that this combination of BCNU implants and TMZ within a multimodal treatment strategy including surgery and RT may provide an enhanced benefit compared with the use of either of these agents alone in select patients with high-grade glioma.
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Papers by Maximilian Mehdorn