Dirk Rasche

Pallidal Stimulation for Dystonia

OBJECTIVE:High-frequency deep brain stimulation (DBS) of the globus pallidus internus (GPi) is a new and promising treatment option for severe dystonia. Yet only few studies have been published to date regarding this treatment. We present the results of DBS of the GPi in 17 patients with severe dystonia of different causes. METHODS:In our study, we included 10 patients with primary generalized dystonia, six patients with secondary generalized dystonia, and one patient with a severe dystonic cervical tremor. In all patients, DBS electrodes were implanted bilaterally within the GPi. Mean follow-up time was 36 months (range, 12–66 mo). Preoperative and postoperative evaluations (at least annually) were performed using the Burk-Fahn-Marsden scale. RESULTS:The best improvement was achieved in patients with DYT1-positive dystonia. Patients with DYT1-negative generalized dystonia showed inhomogeneous results. There was no significant change in patients with tardive dystonia. One case of Hallervorden-Spatz disease improved dramatically within the first 2 years. The improvement in the cervical dystonic tremor was disappointing, however. Three years after DBS implantation, we found a secondary worsening of symptoms in one patient with a DYT1-positive dystonia and in the patient with Hallervorden-Spatz disease. CONCLUSION:DBS of the GPi is a new and promising treatment option for dystonia. Secondary worsening may limit this therapy.

Loss of anisotropy in trigeminal neuralgia revealed by diffusion tensor imaging

We studied the trigeminal nerve in seven healthy volunteers and six patients with trigeminal neuralgia using the diffusion tensor imaging derived parameter fractional anisotropy (FA). While controls did not show a difference between both sides, there was a reduction of FA in the affected nerve in three of six patients with accompanying nerve–vessel conflict and atrophy. Reversibility of abnormally low FA values was demonstrated in one patient successfully treated with microvascular decompression.

Current and future options for the management of phantom-limb pain

Phantom-limb pain (PLP) belongs among difficult-to-treat chronic pain syndromes. Treatment options for PLP are to a large degree implicated by the level of understanding the mechanisms and nature of PLP. Research and clinical findings acknowledge the neuropathic nature of PLP and also suggest that both peripheral as well as central mechanisms, including neuroplastic changes in central nervous system, can contribute to PLP. Neuroimaging studies in PLP have indicated a relation between PLP and the neuroplastic changes. Further, it has been shown that the pathological neuroplastic changes could be reverted, and there is a parallel between an improvement (reversal) of the neuroplastic changes in PLP and pain relief. These findings facilitated explorations of novel neuromodulatory treatment strategies, adding to the variety of treatment approaches in PLP. Overall, available treatment options in PLP include pharmacological treatment, supportive non-pharmacological non-invasive strategies (eg, neuromodulation using transcranial magnetic stimulation, visual feedback therapy, or motor imagery; peripheral transcutaneous electrical nerve stimulation, physical therapy, reflexology, or various psychotherapeutic approaches), and invasive treatment strategies (eg, surgical destructive procedures, nerve blocks, or invasive neuromodulation using deep brain stimulation, motor cortex stimulation, or spinal cord stimulation). Venues of further development in PLP management include a technological and methodological improvement of existing treatment methods, an implementation of new techniques and products, and a development of new treatment approaches.

MRI volumetry for the preoperative diagnosis of trigeminal neuralgia

To assess whether quantitative measuring methods can help improve the reliability of MRI-based evaluations of the pathological role of a neurovascular conflict between an artery and the trigeminal nerve. In a prospective study, magnetic resonance images were obtained from 62 patients with unilateral facial pain and 50 healthy test subjects. In coronal T1- and T2-weighted sequences volume measurements were performed by regions of interest and compared intraindividually (healthy versus affected side in the patient populations and right versus left side in the group of test subjects) and on the basis of the different clinical pictures (t test for dependent and independent samples, p<0.05). In patients with trigeminal neuralgia, the affected nerve showed a smaller volume than the trigeminal nerve on the healthy side (p<0.001). Such a volume difference was noted neither in the other patients nor in the healthy test subjects. Quantitative MRI measurements allow a pathological neurovascular conflict to be distinguished from a nonpathological condition where an artery is in close proximity to the trigeminal nerve. The measured volume difference between the healthy and the affected nerve in patients with neuralgia is indicative of trigeminal nerve atrophy resulting from damage to the nerve.

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.

Altered somatosensory processing in trigeminal neuralgia.

Trigeminal neuralgia (TN) is a pain state characterized by intermittent unilateral pain attacks in one or several facial areas innervated by the trigeminal nerve. The somatosensory cortex is heavily involved in the perception of sensory features of pain, but it is also the primary target for thalamic input of nonpainful somatosensory information. Thus, pain and somatosensory processing are accomplished in overlapping cortical structures raising the question whether pain states are associated with alteration of somatosensory function itself. To test this hypothesis, we used functional magnetic resonance imaging to assess activation of primary (SI) and secondary (SII) somatosensory cortices upon nonpainful tactile stimulation of lips and fingers in 18 patients with TN and 10 patients with TN relieved from pain after successful neurosurgical intervention in comparison with 13 healthy subjects. We found that SI and SII activations in patients did neither depend on the affected side of TN nor differ between operated and nonoperated patients. However, SI and SII activations, but not thalamic activations, were significantly reduced in patients as compared to controls. These differences were most prominent for finger stimulation, an area not associated with TN. For lip stimulation SI and SII activations were reduced in patients with TN on the contra‐ but not on the ipsilateral side to the stimulus. These findings suggest a general reduction of SI and SII processing in patients with TN, indicating a long‐term modulation of somatosensory function and pointing to an attempt of cortical adaptation to potentially painful stimuli. Hum Brain Mapp, 2009.

Behr syndrome variant with tremor treated by VIM stimulation

SummaryBehr syndrome was first described in 1909 as a syndrome of heredofamilial optic atrophy, visual disturbances, nystagmus, and variable pyramidal tract signs. The syndrome has been reported in both sexes. So far, hatremors not been reported to be part of Behr Syndrome. We present the case of a 51-year-old man with a rare complicated dominant inherited cerebellar ataxia with accompanying visual loss and tremor (CICALVT) resembling a Behr Syndrome variant who suffered from advanced visual deterioration since childhood and progressive spastic paraparesis for 15 years. Furthermore, the patient presented increasing tremor of both hands for 5 years. The successful treatment of the tremor using deep brain stimulation (DBS) of the ventral intermediate thalamic nucleus (VIM) is reported. Our case indicates that deep brain stimulation of the ventral intermediate nucleus is an adequate operative intervention that can help to reduce tremor even in patients with complicated movement disorders.

Quantitative Sensory Testing in Patients With Chronic Unilateral Radicular Neuropathic Pain and Active Spinal Cord Stimulation

Objectives.  Spinal cord stimulation (SCS) is an effective treatment option for chronic radicular neuropathic pain syndromes. This prospective study was performed to examine the peripheral effects of SCS on sensation using quantitative sensory testing (QST).

Treatment of trigeminal neuralgia associated with multiple sclerosis: case report.

The incidence of trigeminal neuralgia (TN) in patients with multiple sclerosis is higher than in the general population. If pharmacologic therapy fails, invasive procedures in the gasserian ganglion are usually offered. Microvascular decompression is not routinely performed. The authors report a patient with persistent TN after repetitive trigeminal radiofrequency rhizotomy and finally successful microvascular decompression after demonstration of neurovascular compression with high-resolution MRI.

Peripheral nerve stimulation: lead position monitoring by reconstruction CT angiography—A technical report

BackgroundThe authors investigated the possibility of improving positioning of stimulation leads in patients with chronic neuropathic peripheral nerve pain and good pain relief from implantation of a peripheral nerve stimulator (PNS).MethodsThis pilot study includes four patients suffering from Chronic Regional Pain Syndrome type II (CRPS II) or neuropathic mononeuropathy treated with PNS therapy. The affected extremities and corresponding implantation sites were examined using computer tomographic scans (CT), additional CT angiography (CTA), reconstruction techniques and postprocessing procedures.ResultsIt was possible to prove a close relation between the implanted device and the neurovascular bundle in each of these cases. Thus, indirect lead position control was obtained.ConclusionsComputer tomographic techniques represent a reliable method for the position control of implanted peripheral nerve electrodes. Hence, this procedure should surpass general radiographies in detecting lead displacements.