Nathaniel H. Mayer

Clinicophysiologic concepts of spasticity and motor dysfunction in adults with an upper motoneuron lesion

Spasticity is a disorder of the sensorimotor systme characterized by a velocity‐dependent increase in muscle tone with exagerated tendon jerks, resulting from hyperexcitability of the stretch reflex. It is one component of the upper motoneruon syndrome, along with released flexor reflexes, weakness, and loss of dexterity. Spasticity is an important “positive” diagnostic sign of the upper motoneuron syndrome, and when it restricts motion, disability may result. The “negative” signs‐‐weakness and loss of dexterity‐‐invariably alter patient function when they occur. In an upper motoneuron syndrome, the alpha motoneuron pool becomes hyperexcitable at the segmental level. This hyperexcitability is hypothesized to occur through a variety of mechanisms, not all of which have yet been demonstrated in humans. Spasticity caused by spinal cord lesions is often marked by a slow increase in excitation and overactivity of both flexors and extensors with reactions possibly occurring many segments away from the stimulus. Cerebral lesions often cause rapid build‐up of excitation with a bias toward involvement of antigravity muscles. Chronic spasticity can lead to changes in the rheologic properties of the involved and neighboring muscles. Stiffness, contracture, atrophy, and fibrosis may interact with pathologic regulatory mechanisms to prevent normal control of limb position and movement. In the clinical exam, it is important to distinguish between the resistance due to spasticity and that due to rheologic changes, because the distinction has therapeutic implications. Diagnostic nerve or motor point blocks and dynamic or multichannel EMG are useful to distinguish the contributions of spasticity and stiffness to the clinical problem. 1997 John Wiley & Sons, Inc.Spasticity: Etiology, Evaluation, Management, and the Role of Botulinum Toxin Type A MF Brin, editor. Muscle Nerve 1997; 20 (suppl 6):S1‐S13.

Common patterns of clinical motor dysfunction.

An upper motor neuron syndrome often leads to the development of stereotypical patterns of deformity secondary to agonist muscle weakness, antagonist muscle spasticity and changes in the rheologic (stiffness) properties of spastic muscles. Indentification of the spastic muscles that contribute to deformity across a joint allows therapeutic denervation to be implemented with the maximum likelihood of success. Identifying responsible muscles can be complex, since many muscles may cross the joint involved, and not all muscles with the potential to cause deformity will be spastic. Strategies including polyelectromyography and diagnositc blocks with local anesthetics can be used to test hypoteses regarding the deformity, providing information for more long‐term denervation. In this review, we discuss frequently observed patterns of deformity associated with problematic spasticity, paresis, contracture, and impaired voluntary motor control

Analysis of a disorder of everyday action

Abstract We present a patient, JK, who developed a profound disturbance of routine action production subsequent to closed head injury. Part I of the study describes the disorder as it was expressed in tasks of everyday living. JK demonstrated the features of frontal apraxia, including extreme vulnerability to object substitution and object misuse. In Part II we carried out a neuro-psychological assessment targeted at JKs recognition and understanding of objects and implements. This assessment showed a surprising preservation of low- and high-level vision, as well as semantic knowledge relevant to everyday tasks. It also revealed some areas of weakness, notably in access to semantic memory and gesture recall. It is widely accepted that everyday action tasks are planned and executed automatically, that is, with minimal involvement of executive control processes. JKs defects in the areas of semantic memory and gesture recall may have compromised the automaticity of his action planning, but this alone canno...

Cognitive theory and the study of everyday action disorders after brain damage

This article addresses the question of why some patients with severe traumatic brain injury are unable to carry out even simple, routine activities of daily living without becoming confused and making errors. The argument is developed that such a condition represents “frontal apraxia,” a disorder of executive function defined here as an impairment in the on-line activation of action plans. Two alternatives to this account are considered. One involves a disturbance of attentional control of action; the second involves loss or degradation of the conceptual knowledge base for action. The types of assessments required for differentiating between these alternatives are described and exemplified with reference to specific cases.

The Impact of Instrumented Gait Analysis on Surgical Planning: Treatment of Spastic Equinovarus Deformity of the Foot and Ankle

Background: Despite the logic behind instrumented gait analysis, its specific contribution to clinical and surgical decision making is not well known. Our purpose in this study was to determine the influence of gait analysis with dynamic electromyography upon surgical planning in patients with upper motor neuron syndrome and gait dysfunction. Methods: Two surgeons prospectively evaluated 36 consecutive adult patients with a spastic equinovarus deformity of the foot and ankle. After an initial history and physical exam, each surgeon independently formulated a surgical plan. Surgical treatment options for each individual muscle/tendon unit crossing the ankle included lengthening, transfer, release or no surgery. After the initial clinical evaluation and surgical planning, all patients then underwent instrumented gait analysis collecting kinetic, kinematic and poly-EMG data using a standard protocol by a single experienced physiatrist. Each surgeon reviewed the gait studies and patients independently and again formulated a surgical plan. The surgical plans were compared for each surgeon before and after gait study. The agreement between the two surgeons surgical plans was also compared before and after gait study. Each patient was evaluated for the clinical outcome of surgery. Results: Overall a change was made in 64% of the surgical plans after the gait study. The frequency of changing the surgical plan was not significantly different between the more and less experienced surgeons. The agreement between surgeons increased from 0.34 to 0.76 (p = 0.009) after the gait study. The number of surgical procedures planned by each surgeon converged after the gait studies. Correction of the varus deformity was seen in all patients that underwent surgical treatment. Conclusion: Instrumented gait analysis alters surgical planning for patients with equinovarus deformity of the foot and ankle and can produce higher agreement between surgeons in surgical planning. Clinical Relevance: The equinovarus deformity is due to a variety of deforming forces and a single, best operation does not exist to correct all equinovarus deformities. Rather, a muscle specific approach that identifies the deforming forces will produce the best outcomes when treating the spastic equinovarus deformity.

Comparative Impact of 2 Botulinum Toxin Injection Techniques for Elbow Flexor Hypertonia

OBJECTIVE To compare 2 techniques of botulinum toxin injection for elbow flexor hypertonia. DESIGN Parallel-group, randomized, controlled trial with blinded outcome assessment. SETTING Laboratory, tertiary rehabilitation hospital. PARTICIPANTS Adults (N=31) with acquired brain injury (21 with traumatic brain injury, 8 with stroke, 2 with hypoxic encephalopathy) provided 36 sets of elbow flexors with Ashworth Scale scores equal to 3. INTERVENTION Botulinum toxin type A (BTX-A) was injected with a motor point or a multisite injection technique after obtaining 2 baseline evaluations of the main outcome measures. Motor point technique involved decremental electric stimulation with delivery of 60U of BTX-A (Botox) in 2.4mL or 30U BTX-A in 1.2mL of preservative-free saline at single biceps and brachioradialis motor points, respectively. Distributed injection was performed using electromyographic feedback. Fifteen units in 0.6mL were delivered to each of 4 biceps sites and 2 brachioradialis sites. Total dose (90U) and total injection volume (3.6mL) were identical across groups. Only sites and injection techniques varied. The brachialis was not injected in either group. MAIN OUTCOME MEASURES Ashworth Scale, Tardieu catch angle, and root mean square surface electromyographic activity of the biceps, brachialis, and brachioradialis. RESULTS Postintervention testing at 3 weeks showed no significant differences between groups (P range, .31-.82 across 3 outcome measures). However, within each group, significant treatment effects were observed on all outcome measures (all P<.01). For the uninjected brachialis muscle, electromyographic reduction was greater for the distributed group. CONCLUSIONS In 31 adults with acquired brain injury, single motor point and multisite distributed injections of low-dose, high-volume BTX-A had similar impact. Findings suggest that low-dose, high-volume strategies may have a potential role in reducing drug cost and helping clinicians stay within accepted limits for total body dose in patients with upper motoneuron syndrome requiring many injections.

Instrumented assessment of muscle overactivity and spasticity with dynamic polyelectromyographic and motion analysis for treatment planning.

Esquenazi A, Mayer NH: Instrumented assessment of muscle overactivity and spasticity with dynamic polyelectromyographic and motion analysis for treatment planning. Am J Phys Med Rehabil 2004;83(suppl):S19–S29.

Buttering a Hot Cup of Coffee: An Approach to the Study of Errors of Action in Patients with Brain Damage

Imagine trying to describe the character and severity of an aphasic patient’s language disorder without being able to distinguish word from sentence-level processes, or without invoking grammatical categories (noun, verb, preposition), or without being able to differentiate errors in the grammatical organization of language, from those that arise at the semantic or phonological level of organization. When it comes to disorders of action, clinicians and researchers are handicapped in just this way. What is lacking is a descriptive theory that will do for action what grammatical theories do for language, that is, that will pick out units of action and define their configurational properties at different levels of organization.

Patient registry of outcomes in spasticity care.

ObjectiveThis study aimed to provide clinical injection data and real-world patient-reported and clinical outcomes for the chemodenervation and neurolytic treatment of muscle overactivity including spasticity in patients with traumatic brain injury and stroke. DesignThis study used a prospective multicenter observational design. The participants were 487 patients with stroke or traumatic brain injury. The interventions used were onabotulinumtoxin A or phenol. Nine subjects received both onabotulinumtoxin A and phenol. The main outcome measures were satisfaction and goal attainment, pain, and Ashworth Scale scores. ResultsThe most commonly treated pattern of dysfunction in the upper limb was the flexed wrist, with the flexor carpi radialis as the most frequently treated muscle. The mean total dose for the upper limb muscle was 57.7 ± 34.1 U, and phenol volume was 3.9 ± 0.7 ml. The most commonly treated pattern of dysfunction in the lower limb was the equinovarus/equinus foot, with the medial/lateral gastrocnemius as the most frequently treated muscles. The mean total dose for the lower limb muscle was 93.8 ± 63.5 U, and phenol volume was 4.1 ± 1.3 ml. There was a significant improvement in Ashworth Scale and pain scores. Generally, the patients reported that they were satisfied with their treatment and made progress toward their goals. No significant treatment-related adverse effects were reported. ConclusionsBased on 487 patients with stroke and traumatic brain injury who were selected by their physician and clinical presentation for treatment using chemodenervation and neurolysis, this report of injection data reflecting actual clinical practice may serve as a further clinical guide in the management of patients with muscle overactivity, including spasticity.

Choosing upper limb muscles for focal intervention after traumatic brain injury.

The upper motoneuron syndrome (UMNS) resulting from lesions of corticospinal pathways is an important source of disability after traumatic brain injury (TBI). Classic expressions of motor behavior in UMNS are of 2 kinds: (1) manifestation of muscle underactivity, termed negative signs, and (2) manifestation of a variety of forms of muscle overactivity, termed positive signs. Combinations of negative and positive signs give rise to clinical patterns of movement dysfunction such as the flexed elbow, the clenched fist, and the thumb-in-palm deformity. These clinical patterns can be viewed as reflecting a net balance of muscle forces acting across the joints of a limb. Individual muscles are amenable to a variety of focal interventions such as neurolysis, chemodenervation, or surgery. Since more than one muscle acts across most joints, choices among muscles for focal intervention are many. This article will focus on focal interventions of upper limb muscles of patients with TBI who have UMNS and will explore the theme of choosing upper limb muscles for focal interventions after TBI.