Idiopathische ventrale Rückenmarksherniation

Zusammenfassung

Bei der idiopathischen ventralen Rückenmarksherniation handelt es sich um einen sehr seltenen Defekt der thorakalen ventralen Dura, am häufigsten zwischen BWK 2 und BWK 8, mit konsekutivem Prolaps des Myelons in diesen Duradefekt hinein. Klinisch führt dies oft nach jahrelanger Anamnese zu einer progredienten, mehr oder weniger stark ausgeprägten Myelopathie, z. B. einem Brown-Séquard Syndrom oder einer Paraparese. Die Ursache des Duradefekts und der Mechanismus der Herniation sind nicht geklärt. Diskutiert werden Bandscheibenpathologien wie verkalkte Mikrosporne, Trauma, Entzündung, eine Bindegewebsschwäche und angeborene Dura-Duplikaturen. Die wichtigsten Differentialdiagnosen sind arachnoidale Zysten und arachnoidale Netze (arachnoidal web), die das Myelon bei jedoch intakter Dura nach ventral verlagern, Tumore sowie ischämische und traumatische Myelomalazien. Trotz exzellenter Bildgebung gelingt manchmal die sichere Diagnose einer Myelonhernie samt Duradefekt letztendlich erst intraoperativ. Die operative Versorgung ist, einschließlich auch der nur leicht symptomatischen Patienten, die Therapie der Wahl und stellt eine neurochirurgische Herausforderung dar. Ziel ist das Lösen des Rückenmarks mit, je nach Größe und Lage, entweder Verschluss, Augmentation oder Erweiterung des Duradefekts. Das Risiko für postoperative Defizite beträgt 5–12%. Von einem Behandlungserfolg wird meist bei einem Stopp der klinischen Progression ausgegangen, wobei bis zu 3/4 der Patienten eine Chance auf postoperative Besserung haben. Die operative Behandlung sollte mit intraoperativem Neuromonitoring (SSEP, MEP, D-Welle) in Zentren mit entsprechender Erfahrung erfolgen. Patienten, bei denen noch keine Operationsindikation gestellt wurde, sollten engmaschig angebunden werden, da der natürliche Krankheitsverlauf der idiopathischen ventralen Rückenmarksherniation meist progredient ist.

Abstract

Idiopathic spinal cord herniation is a very rare defect of the thoracic ventral dura, most often between Th 2 and Th 8, with consecutive herniation of the spinal cord into this defect. After a long history, sometimes years, clinical signs and symptoms of a progressive, more or less severe myelopathy ensue, leading to a Brown-Sequard syndrome or parapareses as typical manifestations. Neither cause nor mechanism of the herniation are fully understood, yet. Amongst others, disc disease, like calcified microspurs, trauma, inflammation, connective tissue disorder and inherited duplication of the dura are considered. The most relevant differential diagnoses are arachnoid cysts and arachnoidal webs, that may push the spinal cord ventrally but leave the dura intact, as well as tumors, ischemic and traumatic spinal cord lesions. Despite excellent imaging possibilities sometimes it happens that the actual diagnosis of a spinal cord herniation with an underlying dural defect can only be made during microsurgery. Surgery, also for only mildly symptomatic patients, is challenging but the procedure of choice. The surgical goal is to release the spinal cord and then, depending on its size and location, either to close, augment, or widen the underlying dural defect. The risk for postoperative new deficits is 5-12%. The halt of the clinical progression is considered a treatment success, with ¾ of patients having the chance of postoperative improvement. Surgery should be performed with intraoperative neuromonitoring (SSEP, MEP, D-wave) in experienced centers. Patients in whom the indication for surgery has not yet been made should be closely monitored, because most likely the natural history of idiopathic ventral spinal cord herniation is progressive.

Publication History

Article published online:
29 April 2021

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