The central canal of the spinal cord in experimental hydrocephalus: preliminary results.

The central canal of the spinal cord in certain animal species has been shown to be an alternative pathway of cerebrospinal fluid flow in experimentally induced hydrocephalus. Enlargement and increased movement of cerebrospinal fluid in the central canal has been proposed as a compensatory mechanism in hydrocephalus in humans. The central canal of the spinal cord was normal in 5 dogs and 2 primates made hydrocephalic by a relatively atraumatic experimental model which simulates the human disorder to chronic communicating hydrocephalus. Dilatation of the central canal is apparently not an important compensatory alternative pathway.     

Computed tomography of the spinal canal and cord.

Selective cases have been presented to demonstrate the usefulness of computed tomography in disorders of the spine and spinal cord. The osseous structures are more readily demonstrated than the soft tissues. The cord is difficult and inconsistently identified. However, cystic lesions (syringomyelia) may, at times, be demonstrated. The transverse projection of the CT scan is an added benefit in demonstrating bony spinal lesions. The use of metrizamide with faster scanners should improve the usefulness of this technique in evaluating intraspinal lesions.     

Idiopathic spinal cord herniation: value of MR phase-contrast imaging.

We report two patients with an idiopathic transdural spinal cord herniation at the thoracic level. Phase-contrast MR imaging was helpful in showing an absence of CSF flow ventral to the herniated cord and a normal CSF flow pattern dorsal to the cord, which excluded a compressive posterior arachnoid cyst.     

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.     

MR assessment of the normal position of the spinal cord in the spinal canal.

PURPOSETo investigate intradural geometry, which strongly influences the effects of epidural spinal cord stimulation.METHODSAxial MR images with turbo spin-echo were made of 26 healthy subjects at C-4 through C-6, T-5 and T-6, and T-11 and T-12, at T-11 and T-12 both in the supine and the prone position. Measurements were made of the dorsomedial and the ventromedial cerebrospinal fluid layer and the anteroposterior and transverse sizes of both the spinal cord and the dural sac. The samples of all variables were analyzed statistically. The distance between spinal and vertebral midline was also determined.RESULTSThe dorsal cerebrospinal fluid layer was 1.5 to 4.0 mm at C-4 through C-6 and 4.0 to 8.5 mm at T-5 and T-6. At T-11 it was 2.0 to 6.0 mm in the supine position and was increased by approximately 2.2 mm in the prone position. At T-12 these values were 1.5 to 4.5 mm and approximately 3.4 mm, respectively. Differences between the spinal and vertebral midline up to 1.5 to 2.0 mm occurred in approximately 40% of the images.CONCLUSIONSBecause there are variations of the dorsal cerebrospinal fluid layer among subjects by more than a factor of 2, and significant variations of the mediolateral position of the spinal cord, information on these parameters in patients will be essential for the optimal application of epidural spinal cord stimulation.     

Intraoperative spinal sonography of soft-tissue masses of the spinal cord and spinal canal

Intraoperative spinal sonography (IOSS) was used to evaluate and monitor the progress of surgery in 18 patients with soft-tissue masses of the spinal canal and spinal cord. With intramedullary masses, IOSS showed not only the site of maximum cord enlargement so that a precise biopsy could be performed but also was able to demonstrate the zone of transition between the mass and normal cord tissue. With extradural masses and intradural extramedullary masses, IOSS showed the exact size and location of the masses and confirmed their removal and/or adequate spinal cord decompression. IOSS indicated the extent of bone removal necessary to give adequate exposure to accomplish total removal of these masses or to localize the proper level for tissue biopsy. IOSS also indicated the need to open the dura when there had been unsuspected transdural tumor spread or when bony decompression had not been sufficient to relieve the pressure on the spinal cord in tonsillar ectopia. Intraoperative spinal sonography is recommended in all cases of spinal surgery performed to resect or biopsy soft-tissue masses of the spinal canal or spinal cord.     

Imaging in congenital deformities of the spinal cord

Vertebromedullary malformations are a heterogeneous group of anomalies of mesenchymal and neuroectodermal tissue differentiation or closure in the midline of the back. On the basis of an embryological analysis, the authors describe the more common malformations, placing them at different times of onset and describing the pathological features and radiological findings based on the use of the most appropriate imaging techniques. The most common malformations have been divided into dysraphic and nondysraphic types and malformations affecting the vertebral bodies. The most complex malformations are detected during the antenatal period by ultrasound or foetal magnetic resonance imaging (MRI). Conversely, during the postnatal period, when the patient's clinical conditions do not warrant emergency surgical treatment, the disorder can be better defined with a detailed MRI scan of the brain and spinal cord. In less complex dysraphisms, although MRI is the imaging modality of choice, it may be useful to integrate the study with plain radiography (X-ray) and multidetector computed tomography (MDCT) for a better assessment of the skeletal components. In these disorders, the use of imaging is aimed at both identifying malformative defects and postoperative follow-up of more complex forms.     

Upper cervical spinal cord compression due to bony stenosis of the spinal canal

Compression of the upper cervical spinal cord due to stenosis of the bony spinal canal is infrequent. In the first case reported here, stenosis was due to acquired extensive, unilateral osteophytes centered on the left apophyseal joints of C1–C2 in an elderly professional violinist. In the second case, stenosis was secondary to isolated congenital hypertrophy of the laminae of C1 and C2.     

Central spinal cord lesions in stenosis of the cervical canal

Summary 34 patients suffering from cervical spondylotic myelopathy confirmed by myelography were examined by delayed CT 6–10 h after myelography. Twelve patients showed bilateral intramedullary collections of contrast medium, predominantly cranial to the stenosis. In these patients males predominated, the duration of clinical symptoms lasted longer although their age was lower. There was no correlation to the degree and the extension of the narrowing of the cervical spinal canal. Half of 20 patients undergoing consecutive decompressive surgery showed intramedullary contrast enhancement, and this was shown again by postoperative MRI in eight. The postoperative clinical and neurophysiological results revealed no change in the majority of patients, but three patients showing intramedullary contrast medium deteriorated in neurophysiological outcome, while only one of the patients in whom intramedullary contrast medium was not noticed got worse.     

Idiopathic dilatation of the pulmonary artery

Idiopathic dilatation of the pulmonary artery is an uncommon cause of a large main pulmonary artery whose diagnosis is dependent on the exclusion of other causes of central pulmonary artery dilatation. We present four new cases who have been known to have large central pulmonary arteries for many years, and suggest that a long period of observation should be considered to be a further criterion for diagnosis as, in some patients who appear to have this condition, an underlying pathology will become apparent.     

Isolated central canal rupture of spinal dermoid: report of two cases

We report two cases of lumbar spinal dermoid cysts with asymptomatic rupture and migration of free fat droplets into the central canal. No fatty droplets were seen within the lumbar subarachnoid space. The presence of fat droplets within the central canal is unusual because the central canal is rudimentary in adults. We suggest that hydromyelia secondary to tumour and specific tumour morphology might facilitate the selective rupture of dermoids into the central canal. We recommend a follow up of these patients to detect any possible intracranial migration of fat droplets and resultant complications.     

Intramedullary spinal cord metastases, mainly of nonneurogenic origin

The clinical data and imaging studies of 12 patients with intramedullary metastases were reviewed retrospectively to see if these lesions had a typical radiographic appearance and to determine the sensitivity of the various radiologic examinations. The lesions were identified antemortem by either myelography, CT, MR, and/or intraoperative spinal sonography (IOSS). Final diagnosis was based on biopsy material from either the spinal cord lesion, another metastatic site, and/or the primary tumor. Ten patients had primary tumors located outside the central nervous system, while only two patients had primary brain tumors. Metrizamide myelography and CT demonstrated a definite intramedullary mass in nine of 11 patients. In five patients the mass was relatively small, well-defined, single, and resembled a primary spinal cord neoplasm. In the other four patients, longer and sometimes several segments of the cord were involved. These appeared irregular and nodular and were often associated with intradural lesions at separate sites. MR detected not only enlargement and abnormal signal in the cord but also clinically unsuspected brain lesions. IOSS localized lesions for biopsy and monitored tumor resection. These various imaging procedures showed that cord metastases were often more extensive than anticipated clinically. Spread of tumor into the spinal and intracranial subarachnoid space was common. Imaging of the entire spinal canal and brain, preferably with MR, is therefore recommended to aid in diagnosis, prognosis, and treatment.     

椎管内皮样囊肿破入脊髓中央管的MRI诊断

示腰骶段椎管内皮样囊肿时,应行全脊柱MR扫描,以除外皮样囊肿破裂脂滴进入脊髓中央管的可能性.