Paraplegia and Quadriplegia

Clinical features

Arachnoid cysts may be single or multiple and are usually thoracic. Symptomatic arachnoid cysts are unusual in childhood and encountered more often in adolescents and young adults. The features are back pain or radicular pain and paraplegia. Standing intensifies symptoms, and changes in position may relieve or exacerbate symptoms. The pain tends to increase in severity with time.

Diagnosis

MRI is the diagnostic modality of choice. The cyst has the same MRI characteristics as cerebrospinal fluid (CSF).

Management

Shunting of a symptomatic cyst is curative. However, it is common to blame a subarachnoid cyst for symptoms that have another cause.

Clinical features

The progression of symptoms is usually insidious, and the time from onset to diagnosis may be several years. Subacute or chronic pain is the initial feature in one-third of patients and subarachnoid hemorrhage in one-quarter. Paraplegia is an early feature in only one-third, but monoplegia or paraplegia is present in almost all children at the time of diagnosis. Most children have a slowly progressive spastic paraplegia and loss of bladder control.

When subarachnoid hemorrhage is the initial feature, the malformation is more likely to be in the cervical portion of the spinal cord. Blunt trauma to the spine may be a precipitating factor. The onset of paraplegia or quadriplegia is then acute and associated with back pain. Back pain and episodic weakness that improve completely or in part may be initial features in some children, but impairment is progressive. This type of presentation is misleading, and the diagnosis often delayed.

Diagnosis

MRI is the first step in diagnosis. It distinguishes intramedullary from dural and extramedullary locations of the malformation and may allow recognition of thrombus formation. Arteriography is still necessary to demonstrate the intramedullary extent of the malformation and all of the feeding vessels.

Management

The potential approaches to therapy for intraspinal and intracranial malformations are similar (see Chapter 4 ).

Clinical features

Congenital atlantoaxial dislocation produces an acute or slowly progressive quadriplegia that may begin any time from the neonatal period to adult life. When the onset is in a newborn, the clinical features resemble an acute infantile spinal muscular atrophy (see Chapter 6 ). The infant has generalized hypotonia with preservation of facial expression and extraocular movement. The tendon reflexes are absent at first but then become hyperactive.

Dislocations during childhood frequently follow a fall or head injury. In such cases, symptoms may begin suddenly and include not only those of myelopathy but also those related to vertebral artery occlusion.

Morquio syndrome is primarily a disease of the skeleton, with only secondary abnormalities of the spinal cord. It is also known as mucopolysaccharidosis type IV. Mutations in the GALNS and GLB1 genes result in defective breakdown of glycosaminoglycans (formerly called mucopolysaccharides). Beginning in the second year or thereafter, the following features develop in affected children: prominent ribs and sternum, knock-knees, progressive shortening of the neck, and dwarfism. The odontoid process is hypoplastic or absent. Acute, subacute, or chronic cervical myelopathy develops, sometimes precipitated by a fall. Loss of endurance, fainting attacks, and a “pins and needles” sensation in the arms characterize an insidious onset of symptoms. Corneal clouding, respiratory symptoms, hepatomegaly, and heart valve defects may also occur. Intelligence is usually normal, but life expectancy may be shortened depending on the severity of symptoms.

The essential feature of Klippel-Feil syndrome is a reduced number and abnormal fusion of cervical vertebrae. Mutations in the GDF6 , GDF3 , and MEOX1 genes lead to defective bone formation. As in Morquio syndrome, the head appears to rest directly on the shoulders, the posterior hairline is low, and head movement in all directions is limited. Children often suffer from chronic headaches and neck pain. Elevation of the scapulae and deformity of the ribs ( Sprengel deformity ) are often present. Weakness and atrophy of the arm muscles and mirror movements of the hands are features of evolving paraplegia. Associated abnormalities may be present in the genitourinary, cardiac, and musculoskeletal systems.

Symptomatic atlantoaxial dislocation in children with Down syndrome may occur anytime from infancy to the twenties. Females are more often affected than are males. Symptoms include neck pain, torticollis, and an abnormal gait. Spinal cord compression is progressive and leads to quadriplegia and urinary incontinence.

Diagnosis

C1 usually moves anteriorly to C2. Flexion radiographs assess the separation between the dens and the anterior arch of C1. MRI is best to view the relationship between the cord and the subluxing bones. Flexion-extension plain films of the cervical spine are often used to make the diagnosis, but CT or MRI may be more useful to assess for associated abnormalities. The neck of children with trisomy 21 should not be flexed for lumbar puncture as this may dislocate the atlantoaxial join and cause acute spinal cord compression.

Management

Surgical stabilization of the atlantoaxial junction is a consideration in any child with evidence of spinal cord compression. The choice of surgical procedure depends on the mechanism of compression.

Clinical features

Most Chiari I malformations are discovered as an incidental finding on an MRI ordered because of headache. The malformation is rarely the cause of the headache. The initial features of a symptomatic Chiari malformation are usually insidious. Oropharyngeal dysfunction is a presenting feature in 35% of children less than 6 years of age, followed by scoliosis (23%) and head and neck pain (23%). Among older children, headache and neck pain are the first features in 38% and weakness in 56%. Eighty percent show motor deficits on examination, usually atrophy and hyporeflexia in the arms and spasticity and hyperreflexia in the legs. Sensory loss and scoliosis are each present in half of cases.

Type II malformation should be suspected in every child with myelomeningocele. The child may have hydrocephalus secondary to aqueductal stenosis or by an obstruction of the outflow of CSF from the fourth ventricle due to herniation. Respiratory distress is the most important feature of the Chiari II malformation. Rapid respirations, episodes of apnea, and Cheyne-Stokes respirations may occur. Other evidence of brainstem compression includes poor feeding, vomiting, dysphagia, and paralysis of the tongue. Sudden cardiorespiratory failure is the usual cause of death.

Diagnosis

MRI is the best method to visualize the posterior fossa and cervical cord. CT is useful to further delineate bony abnormalities.

Management

Posterior fossa decompression is the usual technique to manage newborns with myelomeningocele and respiratory distress caused by the Chiari malformation. Unfortunately, the results are not encouraging. Posterior fossa decompression is usually successful in relieving symptoms of cord compression in older children without myelomeningocele. A ventriculoperitoneal shunt may be required as well.

Clinical features

Spina bifida cystica, the protrusion of a cystic mass through the defect, is an obvious deformity of the newborn’s spine. More than 90% are thoracolumbar. Among newborns with spina bifida cystica, the protruding sac is a meningocele without neural elements in 10%–20% and is a myelomeningocele in the rest. Meningoceles tend to have a partial dermal covering and are often pedunculated, with a narrow base connecting the sac to the underlying spinal cord. Myelomeningoceles usually have a broad base, lack epithelial covering, and ooze a combination of CSF and serum. Portions of the dome contain exposed remnants of the spinal cord.

In newborns with spina bifida cystica, it is important to determine the extent of neurological dysfunction caused by the myelopathy, the potential for the development of hydrocephalus, and the presence of other malformations in the nervous system and in other organs. When myelomeningocele is the only deformity, the newborn is alert and responsive and has no difficulty in feeding. Diminished consciousness or responsiveness and difficulty in feeding should suggest perinatal asphyxia or cerebral malformations such as hydrocephalus. Cyanosis, pallor, or dyspnea suggests associated malformations in the cardiovascular system. Multiple major defects are present in approximately 30% of cases.

The spinal segments involved can be determined by locating the myelomeningocele with reference to the ribs and iliac crest. Several patterns of motor dysfunction are observable depending on the cyst’s location. Motor dysfunction results from interruption of the corticospinal tracts and from dysgenesis of the segmental innervation. At birth, the legs are flaccid, the hips are dislocated, and arthrogryposis of the lower extremities is present. Spastic paraplegia, a spastic bladder, and a level of sensory loss develop in infants with a thoracic lesion. Segmental withdrawal reflexes below the level of the lesion, which indicate the presence of an intact but isolated spinal cord segment below the cyst, are present in half of patients. Infants with deformities of the conus medullaris maintain a flaccid paraplegia, have lumbosacral sensory loss, lack a withdrawal response in the legs, and have a distended bladder with overflow incontinence.

Only 15% of newborns with myelomeningocele have clinical evidence of hydrocephalus at birth, but ultrasound detects hydrocephalus in 60% of affected newborns. Hydrocephalus eventually develops in 80%. The first clinical features of hydrocephalus often follow the repair of the myelomeningocele, but the two are not related. Aqueductal stenosis and the Chiari malformation are the cause of hydrocephalus in the majority of infants with myelomeningocele.

Diagnosis

Examination alone establishes the diagnosis of spina bifida cystica. EMG may be useful to clarify the distribution of segmental dysfunction. Cranial ultrasound to look for hydrocephalus is required for every newborn. MRI is useful to define malformations of the brain, especially the Chiari malformation (see Fig. 10.6 ). Therapeutic decisions may require such information. Even in the absence of hydrocephalus at birth, repeat ultrasound examinations in 2–4 weeks are required to evaluate ventricular size.

Management

The chance of surviving the first year is poor without back closure shortly postpartum. However, closure is not a surgical emergency and delays of a week or longer do not influence the survival rate. Other factors associated with increased mortality are a high spinal location of the defect and clinical hydrocephalus at birth. The long-term outcome depends on the degree of neurological deficit from the spinal defect and any associated brain abnormalities.

Clinical features

The initial features of a tethered spinal cord occur at any age from infancy to young adulthood. The clinical features vary with age. External signs of spinal dysraphism (tuft of hair, subcutaneous lipoma, and dermal sinus) are present in more than half of patients, and spina bifida occulta or sacral deformity is present in almost 90%.

Infants and young children are most likely to show clumsiness of gait, stunted growth, or deformity of one foot or leg, and disturbances in bladder or bowel function. These may occur alone or in combination. Consequently, the first specialist consulted may be an orthopedic surgeon, urologist, neurologist, or neurosurgeon. The progression of symptoms and signs is insidious, and a static problem is the first diagnosis in most children. Children with only a clumsy gait or disturbances in urinary control tend to have normal or exaggerated tendon reflexes and an extensor plantar response. In some children, diminished or absent ankle tendon reflexes are noted on one or both sides. Children with foot deformity usually have pes cavus and stunted growth of the entire leg. The other leg may appear normal or have a milder deformity without a growth disturbance. Diminished tendon reflexes in the deformed foot are more likely than increased reflexes.

The initial feature of tethered spinal cord in older children and adolescents is either clumsiness of gait or scoliosis. Bilateral, but mild, foot deformities are sometimes present and urinary incontinence and constipation reported. Exaggerated knee and ankle tendon reflexes are usual, and the plantar response is usually extensor.

Diagnosis

EMG is not a useful screening procedure, as the results are usually abnormal. Radiographs of the spine may show a spina bifida, but MRI is the appropriate diagnostic test and is particularly useful in the detection of lumbosacral lipoma. The essential feature of a tethered spinal cord is a low-lying conus medullaris. At 28 weeks' gestation, the tip of the conus is at the L3 vertebral level. It generally raises one level by 40 weeks' gestation. A conus that extends below the L2 to L3 interspace in children 5 years and older is always abnormal.

Management

Surgical relief of the tethering prevents further deterioration of neurological function and improves preexisting deficits in up to 50% of children.

Clinical features

The age at onset ranges from infancy to late adulthood, with the mean at 29 years. Early and late onset cases may occur among members of the same family. Motor milestones are normal in affected infants except for toe walking. Frequently, the diagnosis in such children is cerebral palsy (CP), especially if the affected parent is asymptomatic or has only a mildly stiff gait. Increased tone is more prominent than weakness. Tone increases slowly for several years and then stabilizes. At this point, the child may have minimal stiffness of gait or be unable to stand or walk.

Usually, tendon reflexes are brisk in the legs and arms, and ankle clonus may be present. However, some children may have absent or diminished ankle tendon reflex due to an associated length-dependent axonal neuropathy. Increased reflexes are usually the only sign of involvement of the arms. Vibratory and position sense are diminished in half of patients. Urinary symptoms, usually in the form of frequency and urgency, and pes cavus deformities each occur in one-third of affected children.

Diagnosis

Familial spastic paraplegia is difficult to diagnose in the absence of a family history, and then becomes a diagnosis of exclusion. This is especially true in childhood when dominant transmission is typical. MRI of the brain and spinal cord is usually normal. The differential diagnosis includes multiple sclerosis, structural abnormalities involving the spinal cord, B ₁₂ deficiency, adrenomyeloneuropathy (AMN) and other leukodystrophies, and dopa-responsive dystonia. The diagnosis of HSP is suspect in any child with very slowly progressive spastic paraplegia. Laboratory studies are not helpful except to exclude other conditions such as adrenoleukodystrophy and argininemia. Multiple causative mutations have been identified, and DNA-based diagnosis is now available for almost all subtypes.

Management

Several centers use Botox injections to relieve spasticity. Many children require ankle–foot orthoses to improve gait. Treatment is not available for the underlying condition.

Clinical features

Spastic paraplegia may begin during infancy or be delayed until adolescence. Involvement of other neurological systems follows. The common associated features, alone or in combination, include cerebellar dysfunction, pseudobulbar palsy, sensory neuropathy, and pes cavus.

Children with sensory neuropathy lose the once hyperactive tendon reflexes in the legs. Some show developmental delay and never achieve bladder control. When sensory loss is progressive, the symptoms resemble those of familial sensory neuropathies described in Chapter 9 . The outcome varies from mild disability to wheelchair dependence.

Diagnosis

In the absence of a family history, the course of disease may suggest CP until the progressive nature of the spasticity is recognized. Sensory neuropathy with mutilation of digits may lead to the erroneous diagnosis of syringomyelia. Laboratory tests are useful only to exclude other diagnoses. Argininemia, a treatable cause of autosomal recessive progressive spastic paraplegia, is a consideration.