An incomplete spinal injury is defined as spinal cord injury with some preserved motor or sensory function below the injury level.
The spared function may be including
- Voluntary anal contraction (sacral sparing)
- Palpable or visible muscle contraction below the injury level
- Perianal sensation present
It must be noted that the completeness of the lesion is the most important prognostic variable relating to neurologic recovery.
Anatomy of Spinal Cord
The spinal cord is located inside the vertebral canal.
To understand the clinical picture by different incomplete injuries
Descending motor tracts are lateral corticospinal tract and ventral corticospinal tract. A lateral injury affects the former and an anterior injury would affect the latter.
Ascending tracts are sensory.
Lateral and ventral spinothalamic tracts carry sensations of light touch, pain and temperature sensation.
Dorsal columns carry deep touch, vibration and proprioreception sensation.
Types of Incomplete Spinal Injury
Anterior cord syndrome
The anterior cord syndrome is characterized by
- Complete motor paralysis below the level of the lesion [corticospinal tract]
- Loss of pain and temperature sensation at and below the level of the lesion [ spinothalamic tract]
- Retained proprioception and vibratory sensation due to intact dorsal columns
- Autonomic dysfunction
- Bladder-bowel dysfunction
The cause is an injury to anterior spinal cord caused by direct compression of the anterior spinal cord or anterior spinal artery injury which is responsible for supply to anterior two-thirds of the spinal cord.
Flexion/compression injury often causes this type of spinal injury. Injury to the anterior spinal artery can also cause anterior cord syndrome.
Anterior cord syndrome has the worst prognosis of incomplete spinal cord injury. There are 10-20% chance of motor recovery
Central cord syndrome
Central cord syndrome is typically observed in syringomyelia, central canal ependymoma, and trauma.
It is associated with more significant arm weakness than leg weakness and variable sensory deficits.
Acute traumatic central cord syndrome is typically considered to be caused by a hemorrhage that affects the central part of the spinal cord. The traumatic injury is usually caused by severe neck hyperextension.
It is the most common incomplete cord injury and us often seen in elderly with minor extension injury mechanisms. Anterior osteophytes and posterior infolded ligamentum flavum are responsible for the injury.
The injury is believed to be caused by spinal cord compression and central cord edema with selective destruction of lateral corticospinal tract white matter.
Because hands and upper extremities are located “centrally” in corticospinal tract, upper extremities and hand are affected in greater quantum.
- Motor deficit worse in upper limb than lower limbs (some preserved motor function)
- Hands have a more pronounced motor deficit than arms
- burning in distal upper extremity
- Neural deficits
- upper limbs have lower motor neuron signs (clumsy)
- lower limbs have upper motor neuron signs (spastic)
This incomplete spinal cord injury has a relatively good prognosis though full functional recovery is rare. Most of the patients usually recover bladder control and are usually become ambulatory.
Upper extremity and hand recovery is unpredictable and patients often have permanent clumsy hands
Lower extremity recovers first, followed by bowel and bladder function and then proximal upper extremity.
Hand function is last to recover
Brown-Sequard syndrome is essentially equivalent to a hemicordectomy or complete cord hemitransection. It is usually seen with penetrating trauma.
- Ipsilateral deficit [On the side of lesion]
- Motor weakness due to corticospinal tract injury
- Proprioception and vibratory sense are affected due to damage to the posterior column ir dorsal column of the spinal cord.
- Contralateral deficit [On the side opposite to lesion]
Pain and temperature sensations affected due to injury to spinothalamic tracts. Spinothalamic tracts cross at spinal cord level, therefore, affecting the contralateral side.
Brown Sequard syndrome carries the best prognosis for functional motor activity. About 99% of people are ambulatory eventually.
Cauda Equina and Conus Medullaris Syndromes
Patients with lesions affecting only the cauda equina can present with a polyradiculopathy with pain, perineal numbness, asymmetric lower motor neuron–type leg weakness, and sphincter disturbances.
Lesions affecting only the conus medullaris cause early disturbance of bowel/bladder function.
More on Cuada equina syndrome
Posterior Cord Syndrome
It is a very rare injury causing loss of proprioception due to injury to the posterior column. Motor function, pain, and light touch sensations are preserved.
In acute situations, the patient may present with spinal shock. In such cases, whether the lesion is complete or incomplete, would be determined only when a patient is out of spinal shock.
Return of the bulbocavernosus reflex determines an end of the spinal shock.
Other reflexes which can be checked are superficial abdominal reflexes [Running a semi-sharp stimulus in any abdominal quadrant and noting umbilical movement], cremasteric reflex, anal wink.
Post spinal shock the picture gets clearer.
The combination of motor weakness, sensory and touch and proprioception and laterality of the symptoms act as a guide to diagnosis.
Identification of affected muscle and the sensory level helps with injury localization.
The motor examination includes the examination of muscle tone, muscle strength, and reflexes.
The sensory examination includes testing of following
- Light touch
- Vibration senses
To know more about the neural examination, please read an examination of the spine.
The spinal fluid examination may be necessary for the evaluation of nontraumatic causes of SCI like transverse myelitis and to rule out other conditions.
- Anteroposterior, lateral, and special views
- Important to show the alignment of bony structures
Important when radiography shows injury or when an area is poorly visualized. Soft tissue changes, cord edema, demyelination, cysts, abscesses, hemorrhage, and calcifications are visible
The best method for visualizing neural tissues. MRI findings correlate with neurologic status and help to establish prognosis.
In the acute stage, spinal injuries require
- Spinal stabilization
- Spine board
- Drugs for pain relief and spasticity control
- Management of hemodynamic and/or autonomic disturbances
- Respiratory monitoring in cases of cervical injuries
- Surgery – decompression and fixation
- Rehabilitation – physical, occupational, vocational, speech and recreational therapies.
- Drugs for spasticity
- Special adaptive devices may for driving
- Computer controlled transcutaneous activation of leg muscle can help with strength training and cardiovascular conditioning.
- Bladder and bowel care -Foley or intermittent sterile catheterization and/or rectal tube or stool softeners
- Pain and anxiety control
- Gastrointestinal prophylaxis against ulcers
- Psychological and emotional support