Myelitis And Acute Transverse Myelitis
Myelitis, or inflammation of the spinal cord, can result from several
diseases. Poliomyelitis affects the cord's gray matter and produces motor
dysfunction; leukomyelitis affects only the white matter and produces sensory
dysfunction. These types of myelitis can attack any level of the spinal cord,
causing partial destruction or scattered lesions.
Acute transverse myelitis, which affects the entire thickness of the
spinal cord, produces both motor and sensory dysfunctions. This form of
myelitis, which has a rapid onset, is the most devastating.
The prognosis
depends on the severity of cord damage and prevention of complications. If
spinal cord necrosis occurs, the prognosis for complete recovery is poor. Even
without necrosis, residual neurologic deficits usually persist after recovery.
Patients who develop spastic reflexes early in the course of the illness are
more likely to recover than those who don't.
Causes
Acute transverse myelitis has a variety of causes. It often follows acute
infectious diseases, such as measles or pneumonia (the inflammation occurs
after the infection has subsided), and primary infections of the spinal cord
itself, such as syphilis or acute disseminated encephalomyelitis.
Acute transverse myelitis can accompany demyelinating diseases, such as
acute multiple sclerosis, and inflammatory and necrotizing disorders of the
spinal cord, such as hematomyelia.
Certain toxic agents (carbon monoxide, lead, and arsenic) can cause a
type of myelitis in which acute inflammation (followed by hemorrhage and
possible necrosis) destroys the entire circumference (myelin, axis cylinders,
and neurons) of the spinal cord.
Other forms of myelitis may result from
poliovirus, herpes zoster, herpesvirus B, or rabies virus; disorders that
cause meningeal inflammation, such as syphilis, abscesses and other
suppurative conditions, and tuberculosis; smallpox or polio vaccination;
parasitic and fungal infections; and chronic adhesive arachnoiditis.
Signs and symptoms
In acute transverse myelitis, onset is rapid, with motor and sensory
dysfunctions below the level of spinal cord damage appearing in 1 to 2
days.
Patients with acute transverse myelitis develop flaccid paralysis of the
legs (sometimes beginning in just one leg) with loss of sensory and sphincter
functions. Such sensory loss may follow pain in the legs or trunk. Reflexes
disappear in the early stages but may reappear later. The extent of damage
depends on which level of the spinal cord is affected; transverse myelitis
rarely involves the arms. If spinal cord damage is severe, it may cause shock
(hypotension and hypothermia).
Diagnosis
A doctor will suspect transverse myelitis in any patient with a rapid
onset of paralysis. Medical history, physical examination, brain and spinal
cord scans, myelogram, spinal tap, and blood tests are used to rule out other
neurological causes of symptoms, such as a tumor. If none of these tests
suggest a cause for the symptoms, the patient is presumed to have transverse
myelitis. Blood tests may be performed to rule out various disorders such as
systemic lupus erythematosus, HIV infection, and vitamin B12 deficiency. In
some patients with transverse myelitis, the cerebrospinal fluid that bathes
the spinal cord and brain contains more protein than usual and an increased
number of leukocytes (white blood cells), indicating possible infection. A
spinal tap may be performed to obtain fluid to study these factors.
Treatment
No effective treatment exists for acute transverse
myelitis. However, this condition requires appropriate treatment of any
underlying infection. Some patients with postinfectious or multiple
sclerosis-induced myelitis have received steroid therapy, but its benefits
aren't clear.