Biomedical subjects

Volker M Tronnier

Publications and source records attributed to Volker M Tronnier.

5 recordsLinked to original sources

PubMed2006

Motor cortex stimulation for long-term relief of chronic neuropathic pain: a 10 year experience.

Chronic subthreshold stimulation of the contralateral precentral gyrus is used in patients with intractable neuropathic pain for more than 15 years. The aim of this study was to analyse retrospectively our own patient group with long term follow-up of 10 years. Seventeen patients with chronic neuropathic pain were treated with contralateral epidural stimulation electrodes. In 10 cases, trigeminal neuropathic pain (TNP) and in seven cases post-stroke pain (PSP) were diagnosed. The placement of the electrodes was performed in local anaesthesia using neuronavigation and intraoperative neuromonitoring. A test trial of minimum one week including double-blind testing was conducted and pain intensity was measured using a visual analogue scale (VAS). Correct placement of the electrode was achieved in all patients using intraoperative neurophysiological monitoring. Double-blind testing was able to identify 6 (35%) non-responders. In 5 of 10 (50%) with TNP and 3 of 7 (43%) with PSP a positive effect with pain reduction > or = 50% was observed. The mean follow-up period was 3.6 years (range 1-10 years) and includes a patient with 10 years of positive stimulation effect. Stimulation of the motor cortex is a treatment option for patients with chronic neuropathic pain localized in the face or upper extremity. Double-blind testing can identify non-responders. Patients with TNP profit more than patients with PSP. The positive effect can last for ten years in long-term follow-up.

Adult↗

PubMed2006

Volumetric measurement of the pontomesencephalic cistern in patients with trigeminal neuralgia and healthy controls.

OBJECTIVE: Most so-called idiopathic trigeminal neuralgias (TN) are caused by neurovascular compression. Does the size of the cerebellopontine cistern play a role in favoring a neurovascular conflict? The aim of this prospective study was to measure the volume of the parapontine cistern in patients with idiopathic TN and to perform a comparison with healthy controls. METHODS: In 25 patients with unilateral idiopathic TN and 17 healthy participants, high-resolution 1.5-T magnetic resonance imaging scans of the parapontine region and the trigeminal nerve were performed. A coronal T2-weighted, true fast imaging steady-state precession sequence with a slice thickness of 0.9 mm was used to define the surrounding cerebrospinal fluid space from the trigeminal root entry zone to Meckel's cave. The volume of the pontomesencephalic cistern was calculated using a standardized method. RESULTS: The mean difference of the volume of the affected and opposite side was 13% in patients with TN. In all patients, a significantly smaller volume of the cistern was found on the affected side (P < 0.01). Healthy controls showed a mean volumetric side difference of 9%, which was not significant (P > 0.05). CONCLUSION: High-resolution magnetic resonance imaging scans are able to demonstrate significant volumetric differences of the pontomesencephalic cistern in patients with unilateral TN. A smaller cistern may be correlated with the occurrence of a neurovascular compression, and these findings support the neurovascular compression theory in idiopathic TN.

Adult↗

PubMed2003

Distinguishing of primary cerebral lymphoma from high-grade glioma with perfusion-weighted magnetic resonance imaging.

To assess the usefulness of perfusion-weighted echo-planar magnetic resonance imaging in the differential diagnosis of primary supratentorial lymphoma (PCNSL) and glioblastoma (GBM), 12 patients with a PCNSL and 12 with a GBM were examined using a 1.5 T magnetic resonance (MR) imager. With dynamic-susceptibility contrast MR imaging the intensity-time curves of each tumor were analyzed, and we determined the relative regional cerebral blood volume ratios (rrCBV [tumor/contralateral white matter (WM)]) to find out whether these parameters could be used to separate PCNSL from GBM. The maximum rrCBV ratio in the PCNSL was significantly lower than that of the GBM (P<0.0001). Comparing the intensity-time curves for the two tumor groups, the PCNSL showed a characteristic type of curve with a significant increase in signal intensity above the baseline due to massive leakage of contrast media into the interstitial space. PCNSL tend to have low maximum CBV ratios and typical intensity-time curves. These two parameters may be useful in distinguishing PCNSL from GBM.

Brain Neoplasms↗

PubMed2003

Subthalamic nucleus stimulation affects a frontotemporal network: a PET study.

Deep brain stimulation (DBS) of the subthalamic nucleus (STN) has become an effective strategy in the treatment of motor symptoms in advanced Parkinson's disease. However, clinical studies have shown that DBS can affect verbal fluency. Seven Parkinson's disease patients with bilateral DBS of the STN were studied with positron emission tomography (PET) to investigate the effects of STN stimulation on regional cerebral blood flow during a verbal fluency task. Activation of the right orbitofrontal cortex and verbal fluency-associated activation within a left-sided frontotemporal network were decreased during STN stimulation compared with the OFF state. Our results offer an explanation for the commonest neuropsychological side effect of STN stimulation and show that STN stimulation affects a frontotemporal network during a fluency task.

Aged↗

PubMed2002

Nerve blocks in stereotactic neurosurgery.

The advantage of performing preoperative nerve blocks of the supraorbital and occipital nerves facilitates frame fixation and the perioperative management of patients in stereotactic neurosurgery, resulting in better patient handling with reduced intraoperative medication and less monitoring by anesthesia personnel.

Aged↗