Definition
Definition
Syringomyelia is a relatively rare disease, characterized by the presence in the spinal cord (more particularly in the cervical segment, corresponding roughly to the neck), of a cavity gradually forming in the gray matter, and containing a pathological (yellowish) fluid.
This results in the progressive destruction of the nerve fibers specialized in the skin's sensitivity to heat, cold, and pain.
Symptoms
Symptoms
The symptoms of syringomyelia depend on the location of the nerve fiber damage:
- Patient's inability to feel the sensation of hot or burns on the hands.
- Feeling of pain hands.
- Disorders of the marche.
- Disorders of speech with paralysis of the tongue.
- Disorders of the swallowing (difficulty swallowing).
- Paresthesias (tingling, prickling sensations) in the face.
- Atrophy muscular that can start with the muscles of the hand, and lead to what is called monkey hand, or main of preacher.
- Atrophy (shrinking) of the skin accompanied by sores (Morvan's whitlow).
- Disorders of reflexes.
The symptoms, known as sub-lesional symptoms, affect the lower limbs and consist of spasmodic paraplegia (paralysis of varying intensity) with exaggerated reflexes and a positive Babinski sign . These symptoms indicate damage to a motor neuron in the pyramidal tract, a major nerve pathway belonging to the central nervous system (brain and spinal cord). It is composed of a bundle of nerve fibers sharing a common path and responsible for transmitting voluntary motor messages (nerve impulses that initiate movement, as opposed to messages related to sensory perception ). It connects pyramidal nerve cells in the cerebral cortex ( the brain's gray matter ) to other nerve cells in the spinal cord.
The changes felt by patients, that is, the symptoms, are the result of a destruction of the peripheral neuron, in this case the neuron that allows sensations from the periphery to be transmitted to the spinal cord, at the level of the lesion. The lesion symptoms affect the upper limbs and their roots.
Pathophysiology
Syringomyelia is a condition characterized by the presence of a cavity within the spinal cord that is not usually present at birth. The cervical spinal cord ( corresponding to the neck) is the most commonly affected area . This cavity typically extends to varying depths within the spinal cord of the thoracic spine.
The lesions resulting from syringomyelia are primarily the destruction of nerve fibers that carry sensory sensations (for the posterior horns of the spinal cord with disturbances of sensitivity) and motor sensations (for the anterior horns of the spinal cord with disturbances of motor function).
- When it is the hind horns of the spinal cord that are affected, the patient suffers fromanesthesia (more or less complete disappearance of superficial or deep sensitivity) more or less significant to temperature, and to pain, in the territory which corresponds to the nerve fibers concerned. This may be the neck, the upper limbs, or the upper part of the thorax.
- When it comes to the anterior horns of the spinal cord, the patient will suffer from disruptions of its motor skills with the appearance, depending on the case, of weakness, muscular atrophy (reduction in muscle volume) or abolition of reflexes (tendinous).
Syringomyelia can progress to syringobulbia , a similar condition characterized by complications in which the malformed cavity is located in the medulla oblongata instead of the spinal cord (as in syringomyelia). In this condition, which does not involve damage to the organs themselves (pharynx, larynx, facial muscles, inner ear, eye), the cranial nerves are affected, leading to disturbances in their function, namely:
- Disturbance of swallowing (the act of swallowing).
- Facial paralysis.
- Disturbance of phonation (the act of making sounds).
- Anesthesia in the territory of the trigeminal nerve (one of the facial nerves).
- Labyrinthine syndrome (affecting the inner ear), and accompanied by a nystagmus which is an involuntary movement of low amplitude oscillation and rotation of the eyeball.
The progression of this condition is unfavorable. Indeed, it can lead to dysfunction of the nerve centers located in the medulla oblongata, which normally (physiologically) regulate breathing, sometimes resulting in syncope and the patient's death.
Medical exam
Physical examination
The patient with syringomyelia presents:
- At the beginning a anesthesia thermoanalgesia, that is, he does not feel temperature differences or pain. However, he retains tactile sensitivity, that is, he feels what he is touching.
- Deep sensitivity is also preserved. This is a dissociation that is the result of a very specific lesion of the spinal cord called a paramedian lesion.
The patient's neurological examination also reveals tendon areflexia (abolition of reflexes).
Some patients present:
- The fibrillations.
- Fasciculations (small muscle movements barely perceptible by the examiner but well described by the patients themselves). This is a kind of tremors, small jumps corresponding to slight disordered contractions of the muscles. They are the result of nervous degeneration.
Additional examination
The diagnosis of syringomyelia is based on nuclear magnetic resonance imaging ( MRI ) which allows visualization of the cavity, and sometimes the malformation(s) at the level of the spinal cord.
Cause
Cause
There are two types of syringomyelia:
- La so-called hydrodynamic syringomyelia, due to a circulation problem of the cerebrospinal fluid between the cerebral ventricles (cavities located in the center of the brain) and the ependymal canal (channel located inside the spinal cord). This type of syringomyelia is due to:
- A congenital malformation of the central nervous system (malformation ofArnold Chiarri).
- A meningitis.
- A tumor.
- Un trauma.
- La so-called non-hydrodynamic syringomyelia, in which a traumatic injury results in the formation of the cavity.
Treatment
Treatment
Treatments for syringomyelia are:
- Treatment of the cause involves the use of psychotropic (central nervous system drugs such as sleeping tablets, the anxiolytics, the neuroleptiques).
- Surgical treatment, when possible, allows decompression through the insertion of a catheter. This indication is mainly due to syringomyelia that progresses and becomes disabling.
- Syringomyelia related to a herniated cerebellar tonsil (part of the cerebellum) is treated by decompression of the posterior fossa (rear part of the contents of the skull) most often after a suboccipital craniectomy (opening of the skull) (passing behind the skull) and an upper cervical laminectomy (intervention on the cervical vertebrae of the upper part of the cervical spine) associated with a dura mater graft (one of the three meninges, membranes, surrounding and protecting the central nervous system).
- When there is an obstruction to flow outside the fourth cerebral ventricle, it is necessary to re-establish the flux of cerebrospinal fluid. This is achieved by widening the opening.
- When the cavity due to syringomyelia is relatively large, some neurosurgeons prefer to try to establish a direct decompression of the fluid cavity. This technique is at the center of a controversy. Indeed, its benefit according to certain neurosurgeons seems linked to a certain morbidity (in a way aggravation of the disease) relatively high.
- In the presence of Budd-Chiari malformation, a hydrocephalus shunt (excess fluid in the skull) which should, in theory, precede any attempt to reduce the cavity due to syringomyelia. Surgical treatment is likely, in theory, to prevent worsening of symptoms related to syringomyelia. Some patients are even likely to improve after neurosurgery.
- Syringomyelia, due to trauma or infection, requires a decompression and drainage technique using small derivations positioned between the syringomyelic cavity and the space located below the arachnoid (one of the three meninges, protective membrane covering the central nervous system).
- Syringomyelia, due to a tumor (in the broad sense of the term) located inside the spinal cord, requires a neurosurgical intervention whose aim is to remove it when this action is of course possible. Decompression of the cystic cavity sometimes results in an improvement which does not always last over time and which is sometimes associated with recurrences.
Evolution
Evolution
Stabilization of syringomyelia sometimes occurs spontaneously, but the progression is very slow. This progression varies depending on the underlying cause. Generally, treatment is not always effective, and its effectiveness varies considerably from individual to individual and, as mentioned earlier, depending on the cause of the condition.
Premature
Morvan's disease, also called Morvan's paronychia (or analgesic paronychia), was first studied in 1883. This condition results from either syringomyelia or leprosy . Morvan's paronychia, or analgesic paronychia, is characterized by neurological disturbances affecting the limbs, primarily the fingers. During the course of this condition, the patient presents with:
- The paresis (a different term from paralysis indicating mild paralysis consisting of a reduction in the ability of muscles to contract).
- A anesthesia (the patient does not feel any sensations).
- The neuralgia (pain due to changes in the nerve structure of peripheral nerves).
- The trophic disturbances (skin modification), resulting in the appearance of analgesic whitlow (loss of pain sensation) concerning the last phalanges. The term trophicity designates all the phenomena conditioning the nutrition and development of a tissue, or an organ.
The progression of Morvan's disease most often leads to the appearance of necrosis, sometimes associated with mutilation.
Differential diagnosis
Syringomyelia should not be confused with:
- La multiple sclerosis.
- La disease ofAran-Duchenne with progressive muscular atrophy (in which there is no sensory disturbance).
- La spinal cord tumor (the diagnosis is made using computed tomography, or nuclear magnetic resonance, and possibly myelography).
- L'hematomyelia usually traumatic in nature. This condition may also be followed by syringomyelia.
- La subacute sclerosis combined bone marrow.