tetraplegia tetraplegia tetraplegia, also known as quadriplegia, is defined as the dysfunction or loss of motor and/or sensory function in the cervical area of the spinal cord. a loss of motor function can present as either weakness or paralysis leading to partial or total loss of function in the arms, legs, trunk, and pelvis; paraplegia is similar but affects the thoracic, lumbar, and sacral segments of the spinal cord and arm function is spared. the paralysis may be flaccid or spastic. a loss of sensory function can present as an impairment or complete inability to sense light touch, pressure, heat, pinprick/pain, and proprioception. in these types of spinal cord injury, it is common to have a loss of both sensation and motor control. tetraplegiaother namesquadriplegiaaffected areas (pink) representing differences between paraplegia (left), hemiplegia (middle), and tetraplegia (right). areas may differ for each condition and are dependent upon level of injury.specialtyneurosurgery, physical medicine & rehabilitationtypescomplete, incompletecausesdamage to spinal cord or brain by illness or injury; congenital conditionsdiagnostic methodbased on symptoms, medical imaging signs and symptoms although the most obvious symptom is impairment of the limbs, functioning is also impaired in the trunk and pelvic organs. this can lead to loss or impairment of controlling bowel and bladder, sexual function, digestion, breathing and other autonomic functions. furthermore, sensation is usually impaired in affected areas. this may manifest as numbness, reduced sensation or neuropathic pain. secondarily, because of their depressed functioning and immobility, people with tetraplegia are often more vulnerable to pressure sores, osteoporosis and fractures, frozen joints, spasticity, respiratory complications, infections, autonomic dysreflexia, deep vein thrombosis, and cardiovascular disease. the severity of the condition depends on both the level at which the spinal cord is injured and the extent of the injury. an individual with an injury at c1 (the highest cervical vertebra, at the base of the skull) will probably lose function from the neck down and be ventilator-dependent. an individual with a c7 injury may lose function from the chest down but still retain use of the arms and much of the hands. an individual in between, with a c5 injury may lose some function from the chest down and fine motor skills in his/her hands but still have flexion and extension abilities of certain muscles around the back or arm area. the extent of the injury is also important. a complete severing of the spinal cord will result in complete loss of function from that vertebra down. a partial severing or even bruising of the spinal cord results in varying degrees of mixed function and paralysis. a common misconception with tetraplegia is that the victim cannot move legs, arms or any of the major function; this is often not the case. some individuals with tetraplegia can walk and use their hands, as though they did not have a spinal cord injury, while others may use wheelchairs and they can still have function of their arms and mild finger movement; again, this varies based on the degree of damage to the spinal cord and is mostly seen with incomplete tetraplegia. it is common to have movement in limbs, such as the ability to move the arms but not the hands, or to be able to use the fingers but not to the same extent as before the injury. furthermore, the deficit in the limbs may not be the same on both sides of the body; either left or right side may be more affected, depending on the location of the lesion on the spinal cord. another important fact to keep in mind would be the possibility to see a person with quadriplegia moving any areas affected by the injury sporadically. one of the main causes for this would be myoclonus, or muscle spasms. "after a spinal cord injury, the normal flow of signals is disrupted, and the message does not reach the brain. instead, the signals are sent back to the motor cells in the spinal cord and cause a reflex muscle spasm. this can result in a twitch, jerk or stiffening of the muscle." causes tetraplegia is caused by damage to the brain or the spinal cord at a high level. the injury, which is known as a lesion, causes the loss of partial or total function of all four limbs, meaning the arms and the legs. typical causes of this damage are trauma (such as a traffic collision, diving into shallow water, a fall, a sports injury), disease (such as transverse myelitis, guillain–barré syndrome, multiple sclerosis, or polio), or congenital disorders (such as muscular dystrophy). cause conditions trauma motor vehicle accident, falls, violence, recreational activity congenital spina bifida, spinal muscular atrophy, cerebral palsy vascular ischemia due to arterial (aortic dissection, atherosclerosis, embolus), venous (thrombosis), or combined (av malformation) causes degenerative amyotrophic lateral sclerosis infectious transverse myelitis (from viral, bacterial, or fungal source) demyelinating multiple sclerosis, guillain–barré syndrome tetraplegia is defined in many ways; c1–c4 usually affects arm movement more so than a c5–c7 injury; however, all tetraplegics have or have had some kind of finger dysfunction. so, it is not uncommon to have a tetraplegic with fully functional arms but no nervous control of their fingers and thumbs. it is possible to have a broken neck without becoming tetraplegic if the vertebrae are fractured or dislocated but the spinal cord is not damaged. conversely, it is possible to injure the spinal cord without breaking the spine, for example when a ruptured disc or bone spur on the vertebra protrudes into the spinal column. anatomy & function since tetraplegia is defined as dysfunction in the cervical spinal cord, this section will focus on the anatomy of the cervical spinal cord. to understand how tetraplegia presents after injury, it is imperative to have a broad knowledge of the cervical spinal roots and it's many functions. in the cervical spine, nerve roots exit the spine above the associated vertebra (i.e. the c6 nerve root exits above the c6 vertebra). by evaluating what nerve root of the cervical spine is injured, the affected muscle groups and dermatomes can be determined. this informs the evaluator as to what activities may be limited as a result of the injury. this is typically done at 72 hours post-injury; exams done prior to this time have been found to be inaccurate due to the presence of swelling and other confounding factors. for example, an injury at the c6 nerve root level will affect the function of the triceps (elbow extension) but the biceps (elbow flexion) will be spared; in this case, an injury at the c6 root level affects all function at that level and below whereas the c5 nerve root, which controls the biceps, is spared since it is above the c6 level in the spinal column. when classifying an individual's level of function, there are numerous functional assessment tools that may be used in a clinical setting and it is often up to the clinician's discretion as to which tools are used. a comprehensive list of these tools may be found on the shirleyryan abilitylab website. key muscle groups & sensory points rootmuscle grouprootsensory point spinal motor & sensory innervations c2-c2> 1 cm lateral to the occipital condyle c3-c3supraclavicular fossa at the midclavicular line c4-c4over the acromioclavicular joint c5elbow flexorsc5lateral antecubital fossa c6wrist extensorsc6dorsal thumb c7elbow extensorsc7dorsal middle finger c8long finger flexorsc8dorsal little finger t1small finger abductorst1medial epicondyle of the elbow t2-t2apex of the axilla cervical spine illustration showing the vertebra and nerve roots diagnosis classification spinal cord injuries are classified as complete and incomplete by the american spinal injury association (asia) classification. the asia scale grades patients based on their functional impairment as a result of the injury, grading a patient from a to d. this has considerable consequences for surgical planning and therapy. after a comprehensive neurologic exam testing segments of the body corresponding to spinal nerve roots, the examiner will determine the patient's motor level and sensory level (i.e. motor level c6, sensory level c7). these levels are unique for the patient's left and right side. this level is assigned based on the lowest (closest to the patient's feet) intact motor and sensory level. after this assignment, a neurological level of injury (nli) is determined. the nli is the lowest segment with intact sensory and motor function provided there is normal sensory and motor function above this segment. american spinal injury association impairment scale a completeno motor or sensory function is preserved in the sacral segments s4–s5. b sensory incompletesensory but not motor function is preserved at s4-s5. no motor function is preserved >3 levels below the motor neurological level of injury. c motor incompletemotor function is preserved below the neurological level; more than half of key muscles below the neurological level have a muscle grade less than 3. d motor incompletemotor function is preserved below the neurological level; at least half of key muscles below the neurological level have a muscle grade of 3 or more. complete spinal-cord lesions as in the above asia chart, a complete spinal cord injury is any injury which has absent motor and sensory function in the sacral segments s4 and s5. this is verified during the physical exam by the absence of all three of: voluntary anal contraction, deep anal pressure, and pinprick+light touch sensation in the perineal area. s4 and s5 are both sacral nerve roots found at the lowest portion of the spinal cord. in simpler terms, "complete" is meant as a way to express that the spinal cord is injured such that no signal, motor or sensory, is carried to or from the level of injury to these lower levels of the spinal cord. incomplete spinal-cord lesions incomplete spinal cord injuries result in varied post injury presentations. there are three main syndromes described, depending on the exact site and extent of the lesion. central cord syndrome: an injury to the central area of the spinal cord, most often seen as a result of a fall with subsequent hyperextension injury. this typically presents with weakness greater in the upper limbs than in the lower limbs. brown-séquard syndrome: hemisection of the spinal cord with resultant loss in: a.) ipsilateral proprioception, vibration, and motor control below the level of injury b.) complete sensory loss at the level of injury c.) contralateral pain and temperature loss. anterior cord syndrome: a lesion of the anterior two-thirds of the spinal cord, most commonly due to ischemia. this typically presents with loss of pain, temperature, and motor function at and below the level of injury. cauda equina syndrome: a lesion of the lumbosacral nerve roots that may spare the spinal cord. as these nerve roots are lower motor neurons, a flaccid lower limb paralysis is typically seen along with loss of bowel and bladder reflexes, varying degrees of impairment of sensation, and loss of sacral reflexes (bulbocavernosus reflex, anal wink). conus medullaris syndrome: a lesion similar to cauda equina syndrome however this lesion is typically found higher in the cord. this presents clinically similarly to cauda equina syndrome however there may be intact sacral reflexes. unlike cauda equina, the unique location of this syndrome leads it to present with mixed upper and lower motor neuron signs. for most patients with asia a (complete) tetraplegia, asia b (incomplete) tetraplegia and asia c (incomplete) tetraplegia, the international classification level of the patient can be established without great difficulty. the surgical procedures according to the international classification level can be performed. in contrast, for patients with asia d (incomplete) tetraplegia it is difficult to assign an international classification other than international classification level x (others). therefore, it is more difficult to decide which surgical procedures should be performed. a far more personalized approach is needed for these patients. decisions must be based more on experience than on texts or journals. the results of tendon transfers for patients with complete injuries are predictable. on the other hand, it is well known that muscles lacking normal excitation perform unreliably after surgical tendon transfers. despite the unpredictable aspect in incomplete lesions, tendon transfers may be useful. the surgeon should be confident that the muscle to be transferred has enough power and is under good voluntary control. pre-operative assessment is more difficult to assess in incomplete lesions. patients with an incomplete lesion also often need therapy or surgery before the procedure to restore