This year’s meeting of the German Society of Neurology took place in Dresden from September 18-21, 2013. We have selected four exciting studies that were highlighted at this congress.
Parkinson’s disease: from the stomach to the brain
Evidence is gradually accumulating that Parkinson’s disease originates decades before the symptomatic phase. According to the so-called Braak stages, deposition of alpha-synuclein in the enteric nervous system, bulbus olfactorius, and dorsal vagus nucleus occurs early in the course of the disease before ascending disease progression reaches the basal ganglia, leading to motor symptoms. Exposure to pesticides could also be described as a possible trigger of this chain reaction.
Researchers in Dresden have now succeeded in demonstrating an ascending deposition of alpha-synuclein in the central nervous system of mice after exposure to the insecticide rotenone. Rotenone-exposed mice also performed worse in balance exercises and had decreased intestinal motility, which can likewise be observed in patients with Parkinson’s disease. However, if the animals had enteric fibers of the vagus nerve cut before exposure to the toxin, alpha-synuclein deposition in the brain was prevented and the operated animals performed better on motor tests.
“The results support the hypothesis that Parkinson’s disease climbs from the stomach via the vagus nerve into the brain,” explained Prof. Heinz Reichmann, MD, director of the Department of Neurology at Carl Gustav Carus University in Dresden. “In the mouse model, we have been able to prevent this by targeting specific nerves to cut. We have now pushed open a door and have a model that could answer many questions and is also well suited for testing new agents.”
Fibromyalgia: expression of small-fibre neuropathy?
Organic causes for fibromyalgia could not be convincingly proven so far, which is why this disease has often been placed in the spectrum of mental disorders. Within the last few years, on the other hand, reports of reduced sensitive pain and temperature thresholds in fibromyalgia patients have been accumulating, which could indicate damage to small nerve fibers, a so-called small-fiber neuropathy.
Researchers at Würzburg University Hospital have put this hypothesis to the test. In 25 patients with fibromyalgia, quantitative sensory testing (QST) was used to determine temperature stimulus thresholds, to derive evoked potentials for pain, and to perform a skin biopsy. Significant differences were obtained in all three tests compared to healthy controls as well as patients with depression. 90% of fibromyalgia patients had pathologic findings on at least two of these tests, whereas routine neurologic and electrophysiologic diagnosis was unremarkable in all groups.
“All three examination methods revealed clear signs of damage to the small nerve fibers in fibromyalgia patients,” explained Prof. Claudia Sommer, MD, of the Department of Neurology at the University of Würzburg. “Our study results confirm that the recommendation in fibromyalgia guidelines for preparations that act on peripheral nerve disorders is correct.”
Epilepsy: Valproic acid harms, folic acid helps
The effects of fetal anticonvulsant exposure on infant IQ are controversial. For this reason, the long-term results of the Anglo-American Pregnancy Registry in women with epilepsy were eagerly awaited.
Children of 305 mothers on anticonvulsant monotherapy (carbamazepine, lamotrigine, phenytoin, valproic acid) during pregnancy were followed up for six years. After accounting for various covariates, the effect of anticonvulsants on infant IQ could be estimated. Thus, fetal exposure to valproic acid resulted in a significant reduction of 8-11 points in childhood IQ at six years of age. This effect was dose-dependent and particularly pronounced for verbal functions. Folic acid administration during pregnancy, on the other hand, had a protective effect on a child’s intellectual development, leading to a significant IQ increase of 7 points.
“For me, this is the most important clinical epilepsy study of the past year,” noted Prof. Bernhard J. Steinhoff, MD, of the Epilepsy Center Kork. “Every neurologist should be aware of these findings and take them into account in practice.”
Epilepsy: On the track of SUDEP
“Sudden unexpected death in epilepsy” (SUDEP) is one of the leading causes of death in individuals with refractory epilepsy, with a frequency of approximately 4:1000 patient-years. The causes and mechanisms for the sudden death of these epilepsy patients are unknown.
It is not surprising that in very rare cases SUDEP may also occur during video-EEG monitoring. The multicenter MORTEMUS project was actually able to document 16 SUDEPs and nine near-SUDEPs in monitored patients through an international survey. The events always occurred after a generalized tonic-clonic seizure and usually at night. This revealed a consistent and previously unknown cardiorespiratory pattern. Postictally, there was initially tachypnea and generalized EEG suppression. About 100 seconds later, bradycardia followed by terminal asystole set in.
The findings suggest a possible centrally regulated autonomic disorder secondary to a generalized tonic-clonic seizure. Because of nocturnal clustering, the authors recommend expansion of nocturnal monitoring on epilepsy units. In outpatients, good seizure control and regular medication are important measures to prevent SUDEP.
Marian Galovic, MD
Source: 86th Meeting of the German Society of Neurology, September 18-21, 2013, Dresden, Germany.
Literature:
- Pan-Montojo F, et al: Environmental toxins trigger PD-like progression via increased alpha-synuclein release from enteric neurons in mice. Sci Rep 2012; 2: 898.
- Üçeyler N, et al: Small fiber pathology in patients with fibromyalgia syndrome. Brain 2013 Jun; 136(6): 1857-1867.
- Meador KJ, et al. (NEAD Study Group): Fetal antiepileptic drug exposure and cognitive outcomes at age 6 years (NEAD study): a prospective observational study. Lancet Neurol 2013 Mar; 12(3): 244-252.
- Ryvlin P, et al: Incidence and mechanisms of cardiorespiratory arrests in epilepsy monitoring units (MORTEMUS): a retrospective study. Lancet Neurol 2013 Oct; 12(10): 966-977.
- Press release of the German Society of Neurology, Trade Press Conference Update Neurology on 20.09.2013
InFo Neurology & Psychiatry 2013; 11(6): 44-46.
