Tone Abnormalities
Muscle tone abnormalities, including spasticity, dystonia, and rigidity, are common after TBI. The types of problems noted vary, depending on the time since injury as well as the severity of injury.
Cause of acquired brain injury also influences the type of problem that is most commonly noted. Spasticity has been noted in 38% and combined spasticity and ataxia in 39% of children and adolescents 1 year after injury (63). Rigidity or dystonia is especially common when there has been secondary injury due to hypoxia or ischemia (81).Spasticity
Spasticity results from an upper motor neuron injury and is manifested by increased deep tendon reflexes and velocity-dependent resistance to movement (82,83). Several different scales are available to evaluate spasticity, but they are all subjective (77), and available quantitative tests are time-consuming (84).
Physical Management. It is important to begin treating spasticity in the acute care setting to prevent contracture development (85). Treatment approaches include range of motion, stretching, casting and splinting, medications, and surgical interventions used alone or in combination to manage spasticity. Range of motion itself may be helpful to reduce tone temporarily (86). Also, one may begin with positioning options, including but not limited to, splinting and weight bearing, if tolerated, as well as the use of neutral warmth, gentle shaking, and reflex inhibition (87). If a child has a tendency to assume a total extension posture, positioning in side-lying with hips flexed beyond 90 degrees and neck flexion may assist in interrupting the extension pattern. If active posturing is present, one must be careful in the use of splints and casts because constant pressure against the splint or cast may result in the development of an ischemic ulcer (87). Stretching should always be included in any treatment protocol for spasticity (77).
Pharmacologic Management. Medications for treatment of spasticity can be oral, intrathecal, or injectable. Enterally administered pharmacologic agents may be beneficial in decreasing abnormal muscle tone and posturing. Their potential side effects may limit their effectiveness in this population. This is especially true of the sedating effects of baclofen and benzodiazepines. Dantrolene sodium causes sedation, despite its action at the sarcolemma. Alpha-adrenergic agonists, such as clonidine and tizanidine, have also been reported to decrease tone (77). The effectiveness of all of these medications is variable.
Early after injury, when posturing may be a problem, chlorpromazine has been of assistance. It has the significant potential to cause sedation (82). Bromocriptine has also been effective in reducing posturing early post injury.
Injectable medications include botulinum toxin and phenol motor point blocks. They can be used in combination with positioning, splinting, and casting. Early after injury, with severe posturing and intolerance of splinting, botulinum toxin may be a helpful adjunct in attempting to maintain range of motion. It is reversible, so if there is significant motor recovery, there is no permanent effect of the injection. Functional gains have been noted with the use of botulinum toxin (88-91). Phenol blocks tend to be used later after injury when there is residual difficulty with increased tone. Phenol and botulinum toxin injections can be used concurrently to treat severe spasticity and to increase the number of muscles treated at one time. If severe deformity develops, surgical tendon or muscle lengthening may need to be considered (81).
Intrathecal baclofen (ITB) infusion using a programmable pump has been shown to be effective in the treatment of spasticity of cerebral origin, particularly cerebral palsy (92,93). Studies have also shown functional improvement in gait (94-96) with the use of ITB infusion in patients with acquired brain injury.
Francisco (97) and colleagues also noted improvement in activities of daily living (ADLs) and decrease in pain. Two studies have shown caregiver and patient satisfaction in individuals treated with continuous infusion of ITB by an implanted programmable pump (98,99). ITB by an implanted programmable pump should be considered if severe systemic spasticity persists (100-102). Doses can be changed, depending on the patient's progress.Dystonia
Dystonia is defined as a disorder in which involuntary sustained or intermittent muscle contractions cause twitching and repetitive movements, abnormal postures, or both (83). It has been reported as a rare motor impairment and is more commonly seen in those injured as children rather than as adults (103,104). Interval between injury and onset of dystonia varies. No consistent picture is seen on neuroimaging study. Medications such as trihexiphenidyl hydrochloride, carbidopa/levodopa, and bromocriptine are used in treating dystonia. ITB infusion has also been used effectively to treat dystonia (101,102).
Rigidity
Rigidity is the resistance to an externally imposed joint movement, with an immediate resistance to reversal of the direction of the movement, and the limb therefore does not tend to return to a particularly fixed posture (83). Management of rigidity is similar to the management of spasticity and dystonia; however, it is often more refractory to intervention.