Spontaneous Spinal Cord Herniation: MR Imaging and Clinical Features in Six Cases

Abstract

Background and Purpose: Spontaneous spinal cord herniation (SSCH) is a rare but important differential diagnosis of spinal cord disorder. The aim of this study was to evaluate the topography and lesion pattern in six patients with SSCH by magnetic resonance imaging (MRI) and their correlation with clinical symptoms. Material and Methods: MRI was evaluated according to intramedullary hyperintense signal changes, alterations of the posterior vertebra and dorsal subarachnoid space at the level of the herniation. Neurologic symptoms as well as their progression were analyzed. Results: SSCH occurred between the level of T3-T7 and were demonstrated best on sagittal and axial T2-weighted images (T2-WI). Hyperintense signals on T2-WI were seen in five patients. Dorsal margins of the vertebra at the level of herniation were scalloped in three patients and one patient showed a sagittal cleft. Mean time from the initial clinical symptoms to diagnosis was 4.2 years. Incomplete Brown-Séquard' syndrome was the most common clinical presentation in our patients (four cases). Conclusion: SSCH is best diagnosed using multiplanar T2-WI with characteristic imaging findings of herniation and adjacent structures. Coexistent notches or even sagittal clefts in the dorsal vertebra raise the hypothesis that SSCH might originate from malfusion of the notochord. ZusammenfassungHintergrund und Ziel: Die spontane Myelonherniation (SMH) ist eine seltene, aber wichtige Differentialdiagnose spinaler Pathologien. Ziel dieser Studie war es, Topographie und Verteilungsmuster der SMH zu ergründen und mit den klinischen Symptomen zu korrelieren. Material und Methodik: Die Bildgebung mittels MRT, CT und Myelographie bei sechs Patienten (vier Frauen, zwei Männer; Durchschnittsalter: 41 Jahre) erfasste intramedulläre Signalalterationen, Veränderungen der Wirbelkörperhinterkanten sowie des Subarchnoidalraumes. Die neurologischen Symptome und deren Verlauf wurden ausgewertet. Ergebnisse: Die SMH erfolgte in Höhe der BWK (Brustwirbelkörper) 3-7 und stellte sich am deutlichsten in den sagittalen und axialen T2-gewichteten Sequenzen dar. Intramedulläre Signalalterationen fanden sich bei fünf der insgesamt sechs Patienten. Assoziierte Einkerbungen der Wirbelkörperhinterkanten traten bei drei Patienten auf, einmal sogar mit sagittaler Spaltbildung. Die Anamnese von initialen Symptomen bis zur Diagnosestellung einer SMH betrug im Mittel 4,2 Jahre. Dabei war ein inkomplettes Brown-Séquard-Syndrom bei vier Patienten die häufigste klinische Präsentation. Schlussfolgerung: Bei klinisch über Jahre langsam progredientem Brown-Séquard-Syndromen in Höhe des oberen und mittleren Thorakalmarkes ist die SMH eine wichtige Differentialdiagnose. Die Ätiologie für dorsale Eindellungen oder sogar Spaltbildungen der korrespondierenden Wirbelkörper könnte in Fusionierungsstörungen des embryonalen Notochords begründet liegen.Schlüsselwörter: Spinale Myelonherniation · Brown-Séquard-Syndrom · Dorsale Arachnoidalzyste · Magnetresonanztomographie · Sagittaler Spalt

Idiopathic spinal cord herniation: Clinical review and report of three cases

“…The most frequent misinterpretation is as a dorsal arachnoid cyst[145678101112131415161718192021232425] previously reported as a false diagnosis in around 45% of cases,[7980] but it has been reported that an associated dorsal arachnoid cyst is potentially present in 20-25% of patients with ISCH. [7980] Other misdiagnoses include thoracic disc herniation,[1213] transverse myelitis,[914] arachnoiditis,[4] intradural mass,[9] and extradural compressive lesion. [1] Misdiagnosis has been reported to result in erroneous surgery, with lack of clinical improvement or progressive neurological symptoms resulting in a second operation to address the spinal cord herniation.…”

The Pathogenesis of Ventral Idiopathic Herniation of the Spinal Cord: A Hypothesis Based on the Review of the Literature

“…The hypothesis is supported by findings described on radiological examination: nuclear trail ( 78 ), clefts in the vertebral body at the level of MRI pathology ( 1 , 96 ), and a cavity in the vertebral body at the level of pathology ( 29 ). A nuclear trail or clefts indicates that the somites did not properly fuse.…”

29 Idiopathic Spinal Cord Herniation

“…Idiopathic spinal cord herniation has an unknown cause which is unrelated to trauma or a previous operation. Pressure erosion, thoracic disc extrusion, congenital disorder (preexisting ventral meningocele), duplication of the ventral duramater, congenital extradural arachnoid cyst, inflammatory process and congenital abnormal adhesions of the spinal cord to the anterior dura are possible underlying causes that have been postulated to explain the occurrence of this dural defect 1,10 .…”

“…1,2). Sagittal T2-weighted MR image showed a focal anterior kink of the spinal cord at the T5-T6 level.…”