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The width of the Cervical Spinal Canal (CSC) had already been measured in healthy persons and different groups of patients because it is an important pathogenetic factor for Cervical Myelopathy. If patients with Multiple Sclerosis (MS) get symptoms of a damage of the cervical spinal cord and show a narrow CSC in the lateral spine X-ray, it is not clear if the symptoms are due to Cervical Myelopathy or to plaques of MS in the cervical spinal cord.

Since development of general purpose scanners, computed tomography (CT) of the entire body has become possible (6). Spatial resolution of modern equipment is already rather good with regard to dense structures such as bone. As a method of axial radiography, CT appears, therefore, well suited for the investigation of the bony spinal canal, for reasons of anatomy and ease of positioning, particularly in the cervical region.

Spondylotic stenosis of the spinal canal is a frequent phenomenon in elderly patients. Jeffreys (1986) reports that 75% of people over 65 years old show a narrowing of the cervical spinal canal. But only a minority of patients suffer from cervical myelopathy due to cervical stenosis. The results of neurosurgical treatment are not uniform and depend on the operation technique.In general, however, surgery has disappointed with regard to an improvement of clinical symptoms.

To substantiate the obstruction of the spinal subarachnoid space in degenerative deformations of the spine causing a spondylogenic myelopathy, we measured spinal elastance (3, 6).

Ventriculo-cisternostomy, introduced by TORKILDSEN in 1939 (8) for the treatment of occlusive hydrocephalus, has been used as a final treatment in patients with nontumorous occlusive hydrocephalus and as a palliative operation in cases with surgically inaccessible deep-seated tumors producing occlusion of CSF pathways within the ventricular system. Since the introduction of ventriculo-atrial and ventriculo-peritoneal shunts, particularly since the beginning of the 1960’s, the number of Torkildsen operations performed in neurosurgical centers has diminished and some neurosurgeons have almost completely abandoned the procedure. Major reviews dealing with indications and results were reported by GERLACH, who analysed 931 patients operated on in the Departments of Neurosurgery in Germany till 1960 (1), GROSCHEL and MARGUTH, who reported on 155 patients operated on between 1951 and 1959 (2), and LANG and P1A (3). Complications of the procedure were reviewed by LORENZ in 1963 (4).

The pathogenesis of chronic cervical myelopathy still leaves some questions to be elucidated. These are associated with problems encountered in diagnosis, differential diagnosis, therapy and in the prognosis of this disease.

We investigated the MR appearance and incidence of low-signal areas within the CSF of the spinal canal. Nonuniform areas of decreased signal intensity in intracranial CSF have been named the CSF flow-void sign (CFVS) and appear to be due to spin dephasing secondary to pulsatile CSF motion. Similar areas are seen in the spinal canal. The MR scans of 50 randomly selected patients, constituting a total of 63 spinal studies, were reviewed. There were 27 cervical, 16 thoracic, and 20 lumbar spine examinations. All patients were studied using T2-weighted and T1-weighted spin-echo pulse sequences. T2-weighted images were done with sufficiently long TE and TR to cause the CSF to appear hyperintense compared with brain and spinal cord tissue. Two patients with enlarged spinal canals and two patients with syringohydromyelia were also included to illustrate the appearance of prominent CSF pulsations. The CFVS was identified on T2-weighted scans in the cervical spinal canal in nine patients (33%), in the thoracic spinal canal in one patient (6%), and possibly in the lumbar spinal canal in two patients (10%). The CFVS was prominent in two patients with enlarged CSF spaces and was also seen in the intramedullary cavity of the patients with syringohydromyelia. The CFVS could obscure small dural lesions and, in some instances, simulate enlarged vessels. Recognition of the spinal CFVS is important to avoid the incorrect diagnosis of intraspinal lesions.