Spinal cord herniation: report of two cases and review of the literature

Idiopathic herniation of the spinal cord is an extremely rare disorder which may cause progressive myelopathy. Two cases of this entity reported herein were both examined using MRI and CT myelography. The typical appearance of this disease with or without a dorsal intradural arachnoid cyst is focal ventral displacement of the mid-thoracic spinal cord, mimicking an isolated intradural spinal arachnoid cyst on MRI. CT myelography using thin slice sections is useful in the diagnosis of this disease. Received 14 August 1995; Revision received 30 January 1996; Accepted 4 June 1996     

Spontaneous thoracic spinal cord herniation through an anterior dural defect.

A 44-year-old woman was examined for progressive left lower extremity weakness and spasticity. Thoracic spine MR imaging and CT myelography showed a ventral dural defect at T7-T8 with an extradural subarachnoid fluid collection and extradural herniation of the spinal cord. Intraoperative sonography confirmed the appropriate level for dural entry and the finding of spinal cord herniation. After reduction of the herniated spinal cord, the patient experienced gradual improvement in neurologic function.     

Transdural spinal cord herniation: imaging and clinical spectra.

PURPOSETransdural herniation of the spinal cord is a rarely reported clinical entity, and many of the existing reports were published before the advent of MR imaging. We describe five current cases and compare them with findings in 25 cases reported in the literature to delineate the clinical and imaging spectra of transdural spinal cord herniation.METHODSMR imaging, CT myelography, and conventional myelography were performed in five patients with transdural herniation of the spinal cord. These studies, along with clinical findings, are described. Intraoperative photographs are included for one case. The salient features of both the current and previously reported cases are summarized in tabular form.RESULTSIn three cases, transdural spinal cord herniation occurred posttraumatically, in one case the cause was iatrogenic and in the others the herniation occurred spontaneously. Imaging features not previously reported include dorsally directed herniations at thoracolumbar levels (two patients), apparent (lacking surgical confirmation) syringomeyelia (one case), a vertebral body nuclear trail sign (one case), and intramedullary hyperintensities on MR images (two cases). Clinical features not previously reported include unilateral pyramidal-sensory deficits (one case) and isolated unilateral pyramidal signs (one case). Clinical findings similar to previous reports include progressive paraparesis (two cases) and progressive Brown-Séquard syndrome (one case).CONCLUSIONOur five cases illustrate certain clinical and imaging findings not previously reported, and, together with the established features of the 25 cases in the literature, delineate the spectra of transdural spinal cord herniation.     

Acute cervical spine trauma: evaluation with 1.5-T MR imaging

Twenty-one patients with acute neurologic deficits following cervical spine trauma were evaluated with magnetic resonance (MR) imaging (n = 21), computed tomography enhanced with intrathecal contrast material (CT myelography) (n = 18), myelography (n = 13), cervical spine radiography (n = 21), and intraoperative sonography (n = 7). MR imaging proved superior to other modalities in demonstrating parenchymal spinal cord injuries and cervical intervertebral disk herniation. Although both T1- and T2-weighted studies appear necessary to evaluate the anatomic relationship of the spinal cord, thecal space, intervertebral disks, and surrounding osseous and ligamentous structures, T2-weighted sequences were more sensitive than T1-weighted studies for detection of spinal cord injury. CT myelography was superior to MR imaging in demonstrating cervical spine fractures. In most cases, myelography revealed no information that was not apparent from both CT and MR imaging studies. Preliminary experience with MR imaging of acute cervical spine trauma suggests that it should be the study of choice in symptomatic patients who are otherwise clinically stable. CT may still be required in selected patients to evaluate complex fractures.     

Value of magnetic resonance myelography in the diagnosis of disc herniation and spinal stenosis

Magnetic resonance imaging provides a good-quality image over the entire length of the spine and can assess the morphology of the discs and cord. It is the imaging modality of choice in the investigation of spinal diseases. Magnetic resonance myelography (MRM) is non-invasive, has comparable sensitivity to conventional myelography in visualizing lumbar nerve roots and allows overall assessment of the spinal canal even in the presence of cerebrospinal fluid block. Seventy-two patients with pre-surgical diagnosis of disc herniation were prospectively investigated prior to surgery to determine the value of MRM in the diagnosis of disc herniation and spinal stenosis. The difference between the sensitivity and accuracy of MRI (89.0-95.6%, 89.1-95.7%) and MRM (82.4-89.0%, 82.6-89.1%) was not significant for both observers. There was no significant improvement with the addition of MRM to MRI (91.2-97.8%, 91.3-97.8%). Although MRM did not significantly improve the diagnostic accuracy of MRI, it allowed a better overall view of the dural sac and root sleeves, therefore making it easier to diagnose spinal stenosis and disc herniation in a minority of cases.     

Thoracic disk herniation: MR imaging

The authors undertook a retrospective study to assess the role of magnetic resonance (MR) imaging in thoracic disk herniation. The initial MR images were interpreted independently of other findings. These interpretations were compared with the findings of plain and computed tomography (CT) myelography and surgery, when available. Sixteen thoracic disk herniations were confirmed with plain and CT myelography and/or surgery. Plain myelography was performed on 14 patients and showed focal ventral filling defects in nine. Results of CT myelography were equivalent to those of MR imaging with three pulse sequences (sagittal T1 and T2 weighted, axial T1 weighted) in the identification of all the abnormal levels. In two patients, the signal from the herniated disk was so low on all sequences that thoracic disk herniation had to be inferred from the mass effect on the spinal cord. Precise location of the abnormal level with body coil MR images was achieved in six of 13 patients.     

Comparison of MR and CT myelography in imaging the cervical and thoracic spine

MR imaging and CT myelography were compared in a retrospective study of 38 patients with suspected lesions of the cervical and thoracic spinal canal and cord. Twenty-eight abnormal cases were found, including spondylosis (9), tumors (8), intramedullary cavities (3), arachnoiditis (3), disk-space-centered infection or osteomyelitis (2), nonneoplastic cord swelling (2), and CSF-borne metastasis (1). MR was equal or superior to CT myelography in depicting cases of cord enlargement, cord compression, and cord atrophy, providing better tissue characterization, no shoulder artifact, and no limitation caused by CSF block. CT myelography was superior to MR in depicting cases of spondylosis and arachnoiditis. It showed superior spatial resolution, which was most pronounced when comparing axial images and hence particularly superior in detecting the lateral extent of disk herniation. Use of surface coils and thin imaging sections is essential for accurate and complete MR evaluation of the cervical and thoracic spine.     

Focal Anterior Displacement of the Thoracic Spinal Cord without Evidence of Spinal Cord Herniation or an Intradural Mass

Objective

We report magnetic resonance imaging (MRI) findings on focal anterior displacement of the thoracic spinal cord in asymptomatic patients without a spinal cord herniation or intradural mass.

Materials and Methods

We identified 12 patients (male:female = 6:6; mean age, 51.7; range, 15-83 years) between 2007 and 2011, with focal anterior displacement of the spinal cord and without evidence of an intradural mass or spinal cord herniation. Two radiologists retrospectively reviewed the MRI findings in consensus.

Results

An asymmetric spinal cord deformity with a focal dented appearance was seen on the posterior surface of the spinal cord in all patients, and it involved a length of 1 or 2 vertebral segments in the upper thoracic spine (thoracic vertebrae 1-6). Moreover, a focal widening of the posterior subarachnoid space was also observed in all cases. None of the patients had myelopathy symptoms, and they showed no focal T2-hyperintensity in the spinal cord with the exception of one patient. In addition, cerebrospinal fluid (CSF) flow artifacts were seen in the posterior subarachnoid space of the affected spinal cord level. Computed tomography myelography revealed preserved CSF flow in the two available patients.

Conclusion

Focal anterior spinal cord indentation can be found in the upper thoracic level of asymptomatic patients without a spinal cord herniation or intradural mass.     

Thoracic disc disease and stenosis

Disc herniation and stenosis in the thoracic spine are relatively uncommon compared with their occurrence in the cervical or lumbar spine. They are usually degenerative, although trauma may be an aggravating or initiating factor. The clinical presentation includes local and/or radicular pain with or without signs and symptoms of cord dysfunction. Radicular pain may be secondary to mechanical compression or vascular impingement. MR imaging is the best way to define the specific abnormality as well as the effect on the adjacent spinal cord. CT after myelography may be useful as well, especially in those patients in whom there is involvement of the posterior ligamentous and osseous structures of the thoracic spinal canal. MR imaging may finally reveal the true incidence of thoracic disc herniation.     

Spinal cord compression due to metastatic disease: diagnosis with MR imaging versus myelography

To determine the efficacy of magnetic resonance (MR) imaging and myelography for the diagnosis of spinal cord compression due to metastatic disease, the authors prospectively examined 70 patients who had known or suspected spinal involvement by malignancy. Most MR examinations consisted of T1-weighted sagittal imaging of the entire spine, with additional sequences as needed for clarification. Extradural masses were found in 46 patients, 25 of whom had cord compression. For extradural masses causing cord compression, the sensitivity and specificity of MR imaging was .92 and .90, respectively, compared with .95 and .88 for myelography. For extradural masses without cord compression the sensitivity and specificity of MR imaging was .73 and .90, versus .49 and .88 for myelography. MR imaging was much more sensitive for metastases to bone (.90 vs .49), as expected. MR imaging is an acceptable alternative to myelography for diagnosing spinal cord compression and is preferable as a first study because it is noninvasive and better tolerated.     

Comparison of myelography, CT myelography and magnetic resonance imaging in cervical spondylosis and disk herniation. Pre- and postoperative findings

Twenty-six patients with cervical radiculopathy and/or myelopathy caused by spondylosis or disk herniation were examined with myelography, CT myelography and MR. Fourteen of the patients were operated upon and 11 of them underwent postoperative MR and CT. The three radiologic methods provided comparable information about narrowing of the subarachnoid space and compression of the spinal cord. It was more difficult to distinguish bone from soft tissue with MR only, but the combination of MR and conventional radiography gave sufficient information for this differentiation. When radiologic nerve root sheath deformity was compared with clinical radiculopathy, myelography, CT myelography and MR had similar sensitivity and accuracy. Postoperative MR could reveal remaining indentation on the thecal sac and the cord but CT without contrast medium was useful as a complement to determine the aetiology of the indentation. Because MR has several practical advantages, it is well suited as the primary imaging modality, together with conventional radiography, for the preoperative radiologic evaluation of patients with cervical radiculopathy and/or myelopathy. Postoperative MR is useful in patients with persistent or new symptoms.     

The impact of magnetic resonance on the diagnostic evaluation of acute cervicothoracic spinal trauma

From 1984 to 1987 magnetic resonance (MR) imaging was performed on 100 patients suffering acute spinal trauma. MR demonstrated one or more injuries to the cervicothoracic region in 31 patients. It displayed a spectrum of spinal cord injury ranging from mild compression and swelling to complete transection. MR was also useful in evaluating alignment at the cervicothoracic junction, in depicting ligamentous injury, in establishing the presence of disc herniation, and in identifying unsuspected levels of injury. We present a diagnostic algorithm that incorporates the role of MR in evaluating acute cervicothoracic spinal trauma and emphasizes the replacement of myelography by MR in the initial assessment of neurologic deficit.     

Haemorrhagic necrosis of the grey matter of the spinal cord due to accidental injection of iopamidol in a patient with multiple neurofibromas; a clinico-pathological study

Summary Cervical laminectomy was performed in a 34-year-old man with multiple spinal neurofibromas because of a slowly progressive medullary compression. Four weeks later a rapid deterioration necessitated iopamidol myelography by left lateral cervical puncture at C2 level. Despite the establishment of adequate spinal fluid contact, resulting in imaging of the subarachnoid space, part of the contrast medium entered the spinal cord, thus delineating a syrinx from the upper cervical extending to the upper thoracic level. After the puncture the patient developed triplegia, involving the left arm and both legs and a paresis of the right arm. He died from aspiration pneumonia. Autopsy revealed haemorrhagic necrosis of the spinal grey matter. This adverse effect of myelography is argued to have been conditioned by the extreme immobility and displacement of the spinal cord due to the presence of multiple neurofibromas. The deterioration four weeks after the operation was probably caused by a further compression of the spinal cord.     

Computed tomographic myelography (CTM) in atlanto-axial rheumatoid arthritis

Summary Thirty-two patients with severe cervical rheumatoid arthritis were investigated preoperatively with cervical myelography (CeM) and computed tomographic myelography (CTM). The severity of their clinical symptoms correlated excellently with a combination of the deformation of the spinal cord at the atlanto-axial level, the lateral dislocation of the cord at the same level, and the deformation of the cord at some lower cervical level. Obstructing softtissue excrescences seemed to have little significance. No correlation was found in this study between the deformation of the cord and the main findings of the plain films: the atlanto-axial subluxation (AAS), the vertical subluxation (VS), or their combination.     

The role of MR imaging in evaluating metastatic spinal disease

Fifty-eight patients with suspected epidural metastases were evaluated with MR imaging. Six patients were examined on two separate occasions. MR was judged to be diagnostic in 60 of the 64 examinations. Twenty-two patients also underwent myelography. MR was as diagnostic as myelography in all cases of epidural metastases. In addition, MR offered several advantages over myelography in the evaluation of metastatic spinal disease, including demonstration of paravertebral tumor extension, identification of additional osseous metastatic lesions, and visualization of areas of spinal cord compression occurring between areas of myelographic blocks. We conclude that MR imaging is the examination of choice for evaluating suspected metastatic spinal disease.     

Idiopathic dural herniation of the thoracic spinal cord

Symptomatic anterior or anterolateral dural herniation of the spinal cord is rare, and not uncommonly misdiagnosed, both clinically and radiologically. We present four patients with a radiological diagnosis of herniation of the thoracic spinal cord, and review the current literature. All affected patients have been adults, typically presenting with long-standing, unexplained sensory symptoms and eventually developing a Brown-Séquard syndrome, with or without motor changes. Herniation occurs in the upper or midthoracic region, between the T2 and T8 levels.     

Emergency magnetic resonance examination of patients with spinal cord symptoms

Eighteen consecutive patients with spinal cord symptoms of sudden or relatively sudden onset were examined with magnetic resonance imaging (MRI). The examinations were performed on a 0.3 tesla permanent/resistive imaging system using solenoidal surface coils. MRI revealed epidural tumour in five patients, intramedullary tumour in one, epidural abscess in one, myelitis in two, spontaneous intraspinal epidural haematoma in two, disc herniation in two, traumatic lesions in four and no abnormality in one patient. MRI was found to be capable of non-invasively and painlessly detecting and exactly defining the extent of intraspinal and paraspinal lesions. In some cases the nature of the lesion could be inferred from specific signal characteristics, which is a unique property of MRI. The results strongly suggest that MRI is superior to myelography and other imaging methods and should be regarded as the examination of choice in the emergency examination of patients with spinal cord symptoms.     

Experimental evaluation of watersoluble contrast media for myelography

Summary An experimental method for testing contrast media for myelography was developed and used to compare three watersoluble contrast media, iocarmate meglumine, iothalamate meglumine and metrizamide after suboccipital myelography in 120 rabbits. A further 71 rabbits served as controls. Iocarmate and iothalamate caused vigorous convulsions; metrizamide did not. Examination of the CSF revealed an acute pleocytosis after installation of the contrast media and after cisternal puncture with injection of hypertonic saline. Histological examination of the spinal cord, nerve roots and meninges revealed pathological changes in 1 of 32 unoperated controls (3%). Leucocyte infiltrations were found in the meninges, nerve roots and spinal cord of about 20% of the animals after myelography, after cisternal puncture without injection or with injection of hypertonic saline. There were no significant quantitative differences between the experimental groups. Degenerative changes were seen only after myelography. No meningeal fibrosis was demonstrated. An abnormal leucocyte count in the primary CSF influenced the incidence of histological changes, indicating that only rabbits with CSF cell counts within normal limits should be used in future experiments.     

MRI新技术在脊髓病变中的研究进展

随着MRI新成像序列的研发,目前已在大脑较普遍使用的各种成像技术亦开始应用到脊髓,并成为脊髓MRI一个重要的发展方向。这些技术主要包括:弥散加权成像(DWI)、弥散张量成像(DTI)、波谱成像(MRS)、血氧水平依赖成像(BOLD)及水成像。另外灌注MRI,脊髓及椎管造影等也在很大方面得到进一步发展。本文将对上述序列的研究进展进行综述。     

Myelography in patients with medulloblastoma.

Unsuspected metastatic medulloblastoma involving the spinal cord was detected by myelography in 2 of 3 patients with newly diagnosed medulloblastoma. Myelography revealed unsuspected spinal cord metastases in an additional patient with recurrent medulloblastoma in the posterior fossa. The authors suggest that myelography be performed prior to radiotherapy in all patients with either primary medulloblastoma or recurrence in the posterior fossa.