Paraparesis is a mild form of lower extremity paralysis that is genetic or caused by a virus. Pain and spasms can be relieved with medication, and physical therapy and exercise can maintain mobility and muscle strength.

Definition of paraparesis

Paraparesis is a medical term used to characterize progressive weakness accompanied by muscle contractures (spastic weakness) in the lower extremities. It is a milder form of paraplegia (paralysis of the lower limbs).

Spastic paraparesis is a group of diseases caused by disorders of the spinal cord.

Types of paraparesis

Spastic paraparesis can be hereditary or caused by a virus.

Hereditary spastic paraparesis

They are divided into uncomplicated (or pure) and complicated (or complex) in the case where the classic signs of lower limb spasticity are accompanied by other signs such as:

• Cerebellar atrophy: a decrease in volume or size of the cerebellum
• A thin corpus callosum (junction between the two hemispheres of the brain)
• Ataxia: movement coordination disorder due to damage to the cerebellum

Genetically, spastic paraparesis can be classified according to their mode of transmission:

• Dominant: it is enough that an abnormality affects a single copy of the gene for the disease to develop.
• Recessive: an anomaly must affect both copies of the gene, each inherited from one of the parents, for the disease to develop.
• X-linked: Men, who have only one X chromosome, get the disease if they carry an abnormality in their single copy of the gene.

Tropical spastic paraparesis

Also called HTLV-1 associated myelopathy, it is a slowly growing disorder of the spinal cord caused by human lymphotrophic T virus type 1 (HTLV-1).

Causes of spastic paraparesis

Hereditary spastic paraparesis can be the result of many types of genetic abnormalities or can develop on their own. Currently, 41 types of hereditary spastic paraparesis are known, but only 17 for which the responsible gene has been identified.

Tropical spastic paraparesis is caused by the HTLV-1 virus.

Diagnostic

Hereditary spastic paraparesis is suspected due to the existence of a family history and any sign of spastic paraparesis.

The diagnosis is firstly based on the exclusion of other possible causes:

• Adrenoleukodystrophy, an X-linked neurodegenerative disease
• Multiple sclerosis
• A disease involving the upper motor neuron (primary lateral sclerosis or amyotrophic lateral sclerosis)
• HIV or HTLV-1 infection
• A deficiency in vitamin B12, vitamin E or copper
• Spinocerebellar ataxia, a neuromuscular disease that affects the cerebellum
• A spinal arteriovenous malformation
• A bone marrow tumor
• Cervicoarthritis myelopathy, a narrowing of the spinal canal that compresses the cervical cord

The diagnosis of hereditary spastic paresis is sometimes made through genetic testing.

The people concerned

Hereditary paraparesis affects both sexes indiscriminately and can occur at any age. It affects 3 to 10 people in 100.

Risk factors

The risk of developing hereditary paraparesis is greater if there is a family history. In the case of tropical spastic paraparesis, the risk of contracting the disease correlates with the risk of being exposed to the HTLV-1 virus, which is transmitted through sexual contact, illicit drug use intravenously or through exposure to blood. It can also be passed from mother to child through breastfeeding.

Spasticity of the lower limbs

Spasticity is defined by an increase in the tonic stretch reflex, that is to say an exaggerated reflex muscle contraction. It causes too high muscle tone which can be the cause of pain and spasms, and cause functional impotence of the limbs.

Motor deficit

People with paraparesis often have difficulty walking. They can trip because they tend to walk on their toes, with their feet turned inward. The shoes are often damaged in the big toe. People often have difficulty going down stairs or slopes, getting into a chair or a car, getting dressed, and grooming.

Asthenia

Asthenia is abnormal fatigue when it persists even after rest. It causes the feeling of being unable to carry out daily activities.

Proprioceptive disorders

Loss of sense of position of feet and toes

Other symptoms

In uncomplicated forms, we can also see:

• Mild disturbances of vibratory sensitivity
• Urinary symptoms (incontinence)
• Hollow feet

In complicated forms,

• Ataxia, disorder of the coordination of movements of neurological origin
• Amyotrophie
• Optic atrophy
• Retinopathy pigmentosa
• Mental retardation
• Extrapyramidal signs
• Dementia
• Deafness
• Peripheral neuropathy
• Epilepsy

Treatment is symptomatic, including treatments to relieve spasticity.

• Systemic drug treatment: baclofen, dantrolene, clonazepam, diazepam, tizanidine, benzodiazepines
• Local treatments: anesthetic block, botulinum toxin (targeted intromuscular), alcohol, surgery (selective neurotomy)

Physical therapy and exercise can help maintain mobility and muscle strength, improve range of motion and endurance, reduce fatigue, and prevent spasms.

Some patients benefit from the use of splints, a cane or crutches.

For tropical spastic paraparesias, several treatments can be useful to fight against the virus:

• Interferon alpha
• Immunoglobulin (intravenously)
• Corticosteroids (such as oral methylprednisolone)

To avoid contracting tropical spastic paraparesis, contact with the HTLV-1 virus should be minimized. It is transmitted by:

• Sexual contact
• Intravenous illicit drug use
• Blood exposure

It can be passed from mother to child through breastfeeding. It is more common among prostitutes, injecting drug users, people on hemodialysis and populations in certain regions including near the equator, southern Japan and South America.