Discordant syringomyelia twins in familial syringomyelia

A case is reported of a pair of monozygous twins who were discordant for and their syringomyelia, and whose brother also suffered from this disease. On the basis of this extraordinarily rare constellation, the role of heredity and the possible importance of environmental factors in the manifestation of syringomyelia are discussed.     

Familial syringomyelia

Summary The clinical and neurological features of four siblings (2 , 2 ) affected by syringomyelia are described. A fifth sister was affected by an acoustic neurinoma. Since neither parent showed signs of syringomyelia, this is considered to be a datum substantiating the dysembryogenetic theory of the syringomyelia syndrome.We are grateful to Dr. M. Savoiardo for his many suggestions and for his interpretation of radiological features. We should like to thank Dr. L. De Lorenzi for allowing us to publish details about patients.     

Familial syringomyelia

Four cases of syringomyelia in two separate families are reported.     

F-responses in syringomyelia

Motor and sensory nerve conduction and various F-response parameters have been examined in the median and ulnar nerves bilaterally in 22 patients with syringomyelia. Excluding those nerves with isolated peripheral lesions, motor and sensory conduction was normal in the distal nerve segments, except for one subject in whom severe wasting of the muscles was associated with slowed motor velocities. Minimum and/or maximum F-response latencies were increased in one or more nerves in 16 of the 22 cases, which was attributed to disturbed function of anterior horn cells and the intraspinal segment of the motor fibres, or mild subclinical nerve trauma. There was a tendency for F-response amplitude and duration to be increased, probably reflecting the combined effects of spasticity and enlargement of motor units due to reinnervation.     

Progress in syringomyelia

Syringomyelia management is showing some progressive improvements following surgical methods of investigation and treatment. Investigation of simultaneous pressure changes in the cerebrospinal fluid pathways has illustrated the importance of craniospinal pressure dissociation in impacting the cerebellar and medullary tissues in the foramen magnum in hindbrain related syringomyelia. Such pressure differences may be referred to as 'suck' and similar changes are to be found in non-hindbrain related forms of syringomyelia such as those associated with spinal arachnoiditis. When cavities have formed then impulsive movements may occur with them and enlargement of the cavities may be continued by sloshing of the fluid within them. Investigations have been improved following the widespread use of water soluble contrast media and CT scanning with reconstructions after myelography. A definite relationship between birth injury and hindbrain related syringomyelia has been established especially with cases showing arachnoiditis. The nature of the relationship to hindbrain hernia and basilar invagination remains unclear. Magnetic resonance imaging holds great promise particularly in showing hindbrain deformation in new-born babies, showing whether or not a communication commonly exists between the fourth ventricle and the cavities within the spinal cord in early childhood and also in outlining the changes in the spinal cord in the presence of acute traumatic paraplegia. Treatment still relies upon valved ventricular to extrathecal shunts for hydrocephalus, cranio-vertebral decompression to prevent suck and drainage of the syrinx in appropriate cases. Syrinx to extrathecal shunting may be preferred to shunts to the subarachnoid space. The peritoneum and the pleura are favoured sites and a valve is not necessary. The advances for the future may depend on earlier diagnosis and greater understanding of the mechanisms of pathogenesis in which MRI seems likely to play an increasingly important part.     

HLA and syringomyelia

The HLA status of 53 patients with syringomyelia was assessed. Forty had an associated Chiari anomaly. A significant increase of HLA-A9 was found. Genetic factors may influence the development of syringomyelia.     

Familial communicating syringomyelia

Calssical cervical syringomyelia was found in 3 members of one family. All 3 underwent air myelogram, and a Chiari malformation type I and postural collapse of the spinal cord was found in each case. An affected 7-year-old boy was discovered after a clinical and radiological survey of 8 first-degree relatives on the basis of mild scoliosis, pyramidal tract signs in the lower limbs and enlarged sagittal diameter of the cervical canal. One other member had basilar impression of the skull but no neurological abnormalities. No positive correlation was found between either the size of the cystic cord enlargement or descent of the ectopic tonsils with the duration or severity of the neurological findings. Suboccipital decompressive craniotomy and upper cervical laminectomy in one case was followed by improvement in strength and sensation 1 year later. Progression in familial syringomyelia appears to occur through a mechanism identical to that in the sporadic form and surgery is therefore also indicated. In affected families, routine survey of close relatives for abnormal neurological signs, and radiological evidence of scoliotic deformity of the spine, enlarged cervical canal and bone abnormalities at the craniovertebral junction may prove valuable for early detection. A dominantly inherited, genetically determined malformation seems to be the probable mechanism of inheritance in this family.     

Post-traumatic syringomyelia.

Post-traumatic syringomyelia was previously thought to be an infrequent but serious sequel to spinal cord injury. Clinical and CT studies have shown an incidence of between 1% and 5%, but more recently MRI has suggested an incidence of up to 22%. Twenty spinal cords have been examined after death from two days to 43 years after injury. Four had syrinxes, 20% of the series, approaching the incidence found by MRI. The acute and chronic pathological changes after trauma are described. Post-traumatic syringomyelia seems to develop from cores of necrotic tissue (myelomalacic cores) rather than lysis of haematoma. The mechanism of extension of syrinxes remains unexplained.     

Pathogenesis of syringomyelia

Formation of syringomyelic cavities may be caused by known pathologic processes, e.g. neoplastic tumours, arachnitis, traumas or malformations of the cranio-vertebral junction, while pathogenesis of idiopathic, primary syringomyelia has not been established so far. This paper presents a historic review of hypotheses and theories concerning the aetiology and pathophysiology of syringomyelia and their critical discussion. It points out the importance of communication between extracellular and subarachnoid spaces through the Virchov-Robin perivascular space. Disturbance of the outflow of extracellular fluid of the spinal cord may lead to dilatation of these canals and to formation of syringomyelic cavities because of raised volume of extracellular fluid.     

Progress in syringomyelia

Syringomyelia management is showing some progressive improvements following surgical methods of investigation and treatment. Investigation of simultaneous pressure changes in the cerebrospinal fluid pathways has illustrated the importance of craniospinal pressure dissociation in impacting the cerebellar and medullary tissues in the foramen magnum in hindbrain related syringomyelia. Such pressure differences may be referred to as 'suck' and similar changes are to be found in non-hindbrain related forms of syringomyelia such as those associated with spinal arachnoiditis. When cavities have formed then impulsive movements may occur with them and enlargement of the cavities may be continued by sloshing of the fluid within them. Investigations have been improved following the widespread use of water soluble contrast media and CT scanning with reconstructions after myelography.

A definite relationship between birth injury and hindbrain related syringomyelia has been established especially with cases showing arachnoiditis. The nature of the relationship to hindbrain hernia and basilar invagination remains unclear. Magnetic resonance imaging holds great promise particularly in showing hindbrain deformation in new-born babies, showing whether or not a communication commonly exists between the fourth ventricle and the cavities within the spinal cord in early childhood and also in outlining the changes in the spinal cord in the presence of acute traumatic paraplegia. Treatment still relies upon valved ventricular to extrathecal shunts for hydrocephalus, cranio-vertebral decompression to prevent suck and drainage of the syrinx in appropriate cases. Syrinx to extrathecal shunting may be preferred to shunts to the subarachnoid space. The peritoneum and the pleura are favoured sites and a valve is not necessary. The advances for the future may depend on earlier diagnosis and greater understanding of the mechanisms of pathogenesis in which MRI seems likely to play an increasingly important part.     

Familial syringomyelia.

A woman with syringobulbia and syringomyelia and her sister with syringomyelia are described. The diagnosis was confirmed radiologically and surgically in the first sister and no other definite abnormalities of her craniocervical junction were found.     

脊髓空洞症的手术治疗

脊髓空洞症由于病因多样，病理过程复杂，其治疗对神经外科医生来说仍是个难题。我科自1991年3月至2001年3月对34例经MRI证实的脊髓空洞症行手术治疗，现将临床情况和治疗方法报告如下，并结合献进行讨论。     

Operative treatment of syringomyelia

There are many methods applied in operative treatment of syringomyelia. They may be divided into three groups: suboccipital decompression, myelotomy with drainage of the syringomyelic cavity, and terminal ventriculostomy. Occipito-vertebral decompression is the treatment of choice in cases of coexisting abnormalities in the region of the occipital foramen. It is also used in cases of syringomyelia without these anomalies. Multiplicity of proposed operative techniques concerns the depth of penetration in the posterior cavity, the width of bony opening and kind of material used for the duroplasty. Myelotomy with syringomyelic cavity drainage is recommended in cases of syringomyelia caused by local traumatic or inflammatory injury of the spine. It is also applied as a supplementary procedure in cases of unsuccessful occipito-vertebral decompression. Terminal ventriculostomy may be recommended in cases of anchoring of the spine and in cases of cavities located in lower parts of the spine and descending to the filum terminale.