Incomplete Spinal Cord Injuries

                                 Dr. KS Dhillon

Introduction

An incomplete spinal cord injury only partially severs the spinal cord. Hence some signals can pass through the level of injury. Incomplete spinal cord syndromes are caused by ascending or descending spinal tract lesions resulting from spinal compression, trauma, or occlusion of spinal arteries. Central cord syndrome, posterior cord syndrome, anterior cord syndrome, and Brown-Séquard syndrome are the most common types of incomplete spinal cord syndromes. The patients present with a dissociated sensory loss. A spine MRI is the diagnostic modality of choice to determine the level, etiology, and extent of the lesion. Treatment will depend on the underlying etiology. Surgery may sometimes be necessary to treat the underlying cause and improve the patient's outcome. Spinal compression is a medical emergency and requires urgent treatment. 

Epidemiology

There are about 11,000 new cases of spinal cord injury per year in the US. Thirty-four percent have incomplete tetraplegia. Central cord syndrome is most common. About 17% have incomplete paraplegia. The remaining 49% are complete. 

Anatomy

The descending tracts are motor tracts (fig 1). The descending tracts include the lateral corticospinal tract (LCT) and the ventral corticospinal tract. The ascending tracts are sensory tracts. The ascending tracts are the dorsal columns, lateral spinothalamic tract (LST), and ventral spinothalamic tract (VST). 

The dorsal columns carries fibers for fine touch, vibration, and proprioception. The lateral spinothalamic tract (LST) carries fibers for pain, temperature, and gross sensation. The ventral spinothalamic tract (VST) carries fibers for light touch. 

Fig 1 

Causes of Incomplete Spinal Cord Injury

There are various events that can forcefully impact the spinal cord and cause an incomplete spinal cord injury. The common causes of incomplete spinal cord injuries include:

• Falls

• Motor vehicle accidents

• Acts of violence

• Gunshot wounds

• Contact sports injuries

Any sort of event that causes compression of the spinal cord can cause a spinal cord injury. Neural tissue damage sustained following a spinal cord injury is usually permanent.

Classification

The extent of sensorimotor loss after an incomplete spinal cord injury primarily depends on the location of the damage. There are 4 main types of incomplete spinal cord injuries that result in different forms of sensorimotor loss. These include:

• Anterior cord syndrome 

• Brown-Sequard syndrome

• Central cord syndrome

• Posterior cord syndrome

Central Cord Syndrome

This is the most common incomplete cord injury. It often occurs in elderly individuals. It can occur with minor extension injury. The cord is injured due to pressure from anterior osteophytes and posterior infolded ligamentum flavum. It is believed to be caused by spinal cord compression and central cord edema with selective destruction of the lateral corticospinal tract white matter. The anatomy of the spinal cord explains why the upper extremities and hand are preferentially affected. The hands and upper extremities are located "centrally" in the corticospinal tract.

There is weakness of the hand. Hand dexterity is most affected. There will be hyperpathia with a burning sensation in the distal upper extremity.  

A physical exam will show loss of motor deficit which is worse in the upper limbs as compared to the lower limbs. There is some preservation of motor function. The hands have a more pronounced motor deficit than the arms. There will be sacral sparing. The late clinical presentation will show that the upper extremities have lower motor neuron signs and the lower extremities will show upper motor neuron signs (spastic).

Treatment can be operative or nonoperative. Treatment options remain 

extremely controversial. The prognosis is generally good although full functional recovery is rare. Age less than 50 years is associated with the greatest neurologic recovery. Patients are usually ambulatory at final follow-up. They usually regain bladder control. The upper extremity and hand recovery is unpredictable. They often have permanent clumsy hands. The recovery occurs in a typical pattern. The lower extremity recovers first, bowel and bladder function next, the proximal upper extremity next, and the hand function is the last to recover.

Anterior Cord Syndrome

Anterior cord syndrome is characterized by motor dysfunction and dissociated sensory deficit below the level of spinal cord injury. Injury to the anterior spinal cord is caused by direct compression (osseous) of the anterior spinal cord and anterior spinal artery injury. The anterior 2/3 of the spinal cord is supplied by the anterior spinal artery. The anterior cord syndrome usually results from a  flexion/compression injury of the spine.

Examination shows that the lower extremity is more affected than the upper extremity. There is damage to the lateral corticospinal tract and the lateral spinothalamic tract resulting in loss of motor function and pain and temperature sensation. The proprioception and vibratory sense are preserved. Of the four incomplete spinal cord injuries the anterior cord syndrome has the worst prognosis. It is most likely to mimic a complete cord syndrome. There is a 10-20% chance of motor recovery.

Brown-Sequard Syndrome

It is also known as lateral cord syndrome. This type of spinal cord injury results from an incomplete transection of the cord. There is complete cord hemitransection. It is usually caused by penetrating trauma. There is damage to both the ascending and descending tracts on only one side of the cord. The injury results in ipsilateral loss of voluntary motor function below the level of injury (lateral corticospinal tract) with contralateral loss of pain and temperature sensation below the injury (lateral spinothalamic tracts). The patient will have varying degrees of loss of perception of touch, vibration, and position below the level of injury. 

The prognosis is usually excellent with 99% of the patients ambulatory at final follow-up. For functional motor activity, it has the best prognosis. 

Posterior Cord Syndrome

Posterior cord syndrome is very rare. Posterior cord syndrome occurs when there’s damage at the back of the spinal cord. It causes a loss of proprioception, difficulties with discriminating between two points of contact with the skin, and loss of ability to feel deep touch below the level of injury.

However, strength as well as the ability to process pain, temperature, and light touch sensations are usually not affected.

Secondary Effects of Incomplete Spinal Cord Injury

Depending on the level and severity of an incomplete spinal cord injury, individuals will experience a wide range of secondary effects. The greater the severity of the spinal cord lesion, the greater the risk of developing secondary complications.

Secondary effects of incomplete spinal cord injuries include:

• Spasticity

• Chronic pain

• Numbness

• Tingling

• Loss of sensation

• Loss of motor control

• Autonomic dysreflexia

• Spinal shock

• Sleep difficulties

• Bowel and bladder dysfunction

• Sexual dysfunction

• Swelling of the extremities

• Cold hands and feet

It is important to be aware of potential complications that make arise following a spinal cord injury so that there can be early intervention. Proper management can help prevent complications from progressing and further interfering with the quality of life. 

Recovery Outlook for Incomplete Spinal Cord Injuries

In patients with incomplete spinal cord injuries, there is only partial damage to the cord, and some neural pathways at the level of injury are spared and remain intact. Communication between the brain and some areas below the level of injury is possible. These spared neural pathways play a critical role in determining recovery. They are capable of utilizing neuroplasticity. Neuroplasticity is the central nervous system’s ability to make adaptive changes based on the behaviors we repetitively practice.

The more we practice a movement affected by SCI, the better the spinal cord gets at perceiving demand for that function. The repetitive stimulation encourages spared neural pathways in the spinal cord to make adaptive changes and rewire functions affected by injury to healthy, unaffected regions.

Generally, the milder the spinal cord injury, the greater is the recovery potential. As long as the spinal cord injury is incomplete, there is potential for functional recovery. With rehabilitative therapies, individuals can receive the targeted treatment they need to develop motor control, manage sensation deficits, cope, and improve their independence.

Treatment for Incomplete Spinal Cord Injuries

Treatment for incomplete spinal cord injury differs for each individual because every SCI and its recovery process is different. Rehabilitative specialists can help individuals identify their specific weaknesses and develop them.  Following is the list of several rehabilitation therapies and management interventions that can assist in incomplete spinal cord injury recovery.

Physical Therapy

Physical therapy focuses on improving an individual’s motor control through repetitive exercises. The therapist can evaluate the individual’s functional abilities and guide them through a customized exercise regimen designed to help stimulate neuroplasticity in the spinal cord, maintain range of motion, and strengthen the muscles. 

Occupational Therapy

Occupational therapy helps individuals develop their functional independence. It teaches individuals to learn new ways to perform everyday activities such as feeding, getting dressed, and performing transfers.

Occupational therapists also teach individuals about risks associated with loss of sensation and/or motor control. Individuals are taught the most effective ways to prevent them. 

Speech Therapy

In patients with a high-level incomplete spinal cord injury, there can be weakness of the orofacial muscles. This can affect their ability to speak, breathe, and eat on their own. Speech-language pathologists can help individuals to learn effective ways to manage their orofacial deficits and improve them.

Psychotherapy

Incomplete spinal cord injury directly affects motor control and sensation and this can affect an individual’s mental health. Learning to cope with life after a spinal cord injury may be challenging. It requires some major lifestyle adjustments. Psychotherapy can help individuals better understand their negative feelings and help them effectively cope and overcome them.

Orthotics

Individuals with weakness in their limbs following an SCI can have difficulty maintaining correct form during movement. Wearing orthotic devices such as splints and braces can help provide structural support.

Many individuals with incomplete spinal cord injuries experience spasticity. This can negatively impact an individual’s form and posture. Wearing an orthotic device can help hold the spastic limb in place to prevent contractures and gently stretch the spastic muscles.

Medications

Spasticity can make it difficult for individuals with spinal cord injuries to participate in rehabilitative therapies because tight muscles restrict their range of motion. Nerve blockers like Botox or muscle relaxants like baclofen can help temporarily relieve spasticity. This helps individuals to participate more fully in their rehab therapies. Improvements made while using Botox or baclofen can be long-lasting due to neuroplasticity.

Additional medications can be prescribed depending on the types of secondary complications that arise.

Surgery

Surgery is sometimes indicated when there is severe forms of spasticity after incomplete SCI. The surgery is to reduce muscle tightness. Surgery for spasticity reduction includes manual lengthening of the affected muscles and tendons or selective incisions of the nerves to reduce the excitability of muscle contractions.

Conclusion

Incomplete spinal cord injuries produce partial loss of motor control and sensation in areas below the level of injury. Since some areas of the spinal cord at the level of injury are unaffected, there is potential for spared neural pathways to utilize neuroplasticity and recover functions affected by the damage.

Through intensive, targeted rehabilitation, individuals with incomplete spinal cord injuries can regain motor control and significantly improve their quality of life.