Quadriplegia is the loss of voluntary movement and sensation in all four extremities, and usually results from a cervical spinal cord injury (SCI). Other conditions, such as a brain stem lesion or cervical spinal stenosis, may also result in quadriplegia, also known as tetraplegia.
An SCI can be complete or incomplete. The term incomplete indicates that the patient has some sensory or motor function below the injury level.
There are seven cervical vertebrae and eight cervical nerves, identified as C1 through C8. The level of injury directly correlates to the patients abilities and needs.
Patients with an injury at C1, C2, and higher have little or no movement of their head and neck, and are entirely dependent on ventilatory assistance for breathing.
Patients with an injury at C3 usually have control of their head and neck, and are occasionally weaned from ventilatory assistance.
Patients with an injury at C4 usually have control of their head and neck, some shoulder movement, and are often weaned from ventilatory assistance.
Patients with injuries at C5 and lower have control of their head and neck, progressively more control of their arms and hands, and are rarely in need of ventilatory assistance.
Patients with injuries below the cervical spine have full function in the upper extremities, which is classified as paraplegia. Paraplegics do not lose control of respiratory drive.
Breathing Pacemakers for Quadriplegics
The phrenic nerves are the pathways between the brain and the diaphragms which originate at C3 through C5. Injuries at or above C3 interrupt these pathways and render the patient dependent on ventilatory assistance. Immediately following injury, this assistance is provided by a mechanical ventilator. After the patient is stable, and cannot be weaned from mechanical ventilation, a breathing pacemaker can be considered.
A breathing pacemaker is a surgically implanted phrenic nerve stimulator which delivers electrical impulses to the diaphragms and restores breathing function. It is indicated for quadriplegia in ventilator-dependent patients whose diaphragm, lungs, and phrenic nerves have residual function. Preoperative screening is determined by the patient’s physicians, but typically includes EMG studies of phrenic nerve conduction, and pulmonary function tests.
Diaphragm Paralysis is the loss of control of one or both hemidiaphragms caused by a traumatic injury or disease process which decreases or terminates the impulse of respiratory stimuli originating in the brain. Causes of diaphragm paralysis include, but are not limited to:
• Central neurological disorders such as a brain or brainstem stroke,
• Spinal cord disorders such as spinal cord compression or spinal cord tumors,
• Direct trauma to the phrenic nerve from surgery, radiation, or chiropractic neck manipulation,
• Demyelinating disease processes such as Guillan-Barré syndrome and ALS (Lou Gehrig’s Disease),
• Phrenic nerve neuropathy, viral or bacterial infections, and unknown (ie, idiopathic) etiologies.
