What is Spinal Dysraphism

Spinal dysraphism (from the Latin raphe – the seam) – is a diverse group of heterogeneous congenital malformations of spine and spinal cord, characterized by a split in the spinal column (called spina bifida). There are two main types of spinal dysraphism:

Occult  spinal dysraphism (spina bifida occulta), where there is no violation of the integrity of the skin over the defect in the vertebrae;

Open (hernial) spina bifida (spina bifida cystika), where there is a clear violation of the integrity of the skin over the site cleft spine formation hernial protrusion whose contents may be spinal cord and / or its membranes.

Occult  spinal dysraphism  (OSD) occurs most frequently. This form of cleft spine may not be accompanied by any neurological deficits, if the observed splitting of the arc only one or two vertebrae, usually the fifth lumbar (spina bifida L5) and / or the first sacral (spina bifida S1). Most people with the form of cleft spine don’t feel any symptoms or problems, they often become aware of its defects randomly spine X-ray examination conducted for other reasons. That is why the true frequency of OSD is unknown.

However, the notion of “Occult  spinal dysraphism  ” also includes such forms as myelodysplasia, tethered  spinal cord syndrome, the spinal cord splitting, spinal lipoma, dorsal dermal sinus, etc. In these cases, the OCSD is usually accompanied by severe orthopedic neurological symptoms: lower paraparesis (weakness in the legs), decreased muscle tone, muscle atrophy, urinary and fecal incontinence, reduced sensation in the legs and perineum, spinal deformities (kyphosis, lordosis, scoliosis) and feet, paralytic instability of the hip joints, etc.

If there are neurologic symptoms OCSD are frequently (up to 70-80% of cases) associated with hydrocephalus – fluid in the brain, are often occured with a combination of abnormalities, as Arnold-Chiari malformation (low location of the hemispheres of the cerebellum) and syringomyelia (formation of the cysts within spinal cord). OCSD may also have cutaneous manifestations: a site of excess body hair (hypertrichosis), angiomas, Sinus tract  course, subcutaneous lipoma, caudal appendage, or a combination thereof.

OCSD may not manifest itself immediately after birth, but neurological deficit has an insidious onset. That is why it is necessary to diagnose it using magnetic resonance imaging (MRI) of the spinal cord. The slow progression of OCSD symptoms as the child grows, is primarily connected to the so-called tethered spinal cord syndrome (TSC- syndrome).

TSC is characterized by abnormally low (below the L1-L2) location of a spinal cord terminal part – the cone. It is known that spinal cord in its fetal development and during the growth of the child moves up into the spinal canal. Being tough is pathologically fixed terminal thread, the spinal cord cannot follow the growing spine. Neurological disorders cannot be among young children, because the spinal cord is fixed, but not tight. But gradually there is an infringement of blood circulation in the lower regions of the spinal cord as a result of tension. This leads to lower back pain and pain in legs, gait disturbance and the development of flaccid paraparesis, the lower muscular atrophy, deformation and shortening of the lower limbs, sensory disturbances in the legs and perineum, urinary and fecal incontinence, development of scoliosis and other problems.

The splitting of the spinal cord (SSC) – another version of the OCSD, which is characterized by the presence inside the spinal canal of a bone, cartilage or fibrous septum, which is wholly or partially divides along the spinal cord into two halves (hemichords). According to Pang modern classification two types of the SSC are stated. In the type I, there are two separated by a jumper hemichords, each of which is in its own dural sac, in the type II both halves of the spinal cord are enclosed in a single dural sac and separated by a fibrous septum. Symptoms in the SSC are determined by fixing the spinal cord, which is pathologically retained bone, cartilage or a septum. 90% of patients reveal signs OSDs on their skin, most often, hypertrichosis. Split spinal cord is visible on MRI, but the level of septum is better to identify with the X-ray computer-based tomography, which visualizes the bone structures.

Another form of OCSD is spinal lipoma (benign tumors of adipose tissue). They can be located intraduraly or be soldered to the cone of the spinal cord or the terminal thread. Intradural (located inside the dura mater), lipoma in the lumbosacral segment, as well as ones, infiltrating the terminal thread, lead to a pathological fixation and tension of the spinal cord. Lipomas of the cone of spinal cord also fix it on lower loins level, and can be combined with subcutaneous myelomeningocele or mielotsistotsele (see below).

Dorsal dermal sinus – is a malformation characterized by the presence of the sinus tract, which is often located in the lumbosacral region of the spinal column and can reach the subarachnoid space of the spinal cord. Sinus tract is lined with epithelium. The main feature of the dermal sinus is the presence of a small skin opening, around which there is redness or excessive hairiness. Sinus tract  course serves as a guide and source of infection of meningitis, epidural and subdural abscesses.

Treatment of patients with various forms of OCSD is surgical. The purpose of the operation with TSC- syndrome is the unfixing of the spinal cord. In other cases the purpose and technique of surgical intervention depends on the shape of OCSD. Improvement or stabilization of neurologic function occur in 90% of operated patients.

In the Open spina bifida, also referred to as Spinal disk’s herniation, consisting of the meninges hernial sac of varying size protrudes through the bone defect, containing cerebrospinal fluid – lIquor (meningocele), or cerebrospinal fluid and spinal cord nerves roots tissue (meningoradikulotsele), or apart from these components, the spinal cord tissue (myelomeningocele). There are also mielotsistotsele – local extension of central channel with a bulging of the back of the thinning spinal cord. Mielotsistotsele contains cerebrospinal fluid (CSF), surrounded by the substance of spinal cord and its meninges and the posterior roots of spinal cord nerves. CSF leak often occurs in case of herniated disk.

Neurological disorders in the open forms of spinal dysraphism depend on the contents of the hernial sac and its localization (cervical, thoracic or lumbosacral level). About half of the meningocele is asymptomatic, but 25% of the meningocele is combined with hydrocephalus. When the incidence of myelomeningocele hydrocephalus is about 70-80%. About the same percentage of myelomeningocele is localized in the lumbar and lumbosacral spine, causing flaccid paraparesis or no active movement in the lower extremities, impaired sensation in the legs and/or pelvic disorders. During the localization of spinal herniation on cervical level the upper limbs are being involved in the pathological process.

Open forms of spinal dysraphism is not difficult to diagnose and are subject to surgical intervention. Operation frees patients from the hernial protrusion, but in this case prognosis is less favorable in point of return development of neurological disorders as the result of irreversible changes in the spinal cord and its roots. After surgical removal of hernial protrusion hydrocephalus may develop. After correction of myelomeningocele and lipomielomeningotsele TSC syndrome develops among 10-75% of children.

Children need long-term rehabilitation after surgical treatment of spinal dysraphism various forms.