Spasticity, etiology, evaluation, management, and the role of botulinum toxin type A

M. F. Brin, K. Albany, D. Alexander, T. Cava, H. G. Chambers, M. K. Childers, C. Comella, E. Elovic, A. Esquenazi, Jr Gormley, J. M. Gracies, C. Ivanhoe, J. Jankovic, J. Leach, J. McGuire, N. H. Mayer, C. F. O'Brien, S. H. Pierson, B. S. Russman, D. M. SimpsonA. Tilton, S. A. Yablon

Research output: Contribution to journalReview articlepeer-review

10 Scopus citations


Spasticity is a disorder of the sensorimotor system characterized by a velocity-dependent increase in muscle tone with exaggerated tendon jerks, resulting from hyperexcitability of the stretch reflex. It is one component of the upper motoneuron 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.

Original languageEnglish
Pages (from-to)S1-S223
JournalMuscle and Nerve
Issue numberSUPPL. 6
StatePublished - 1997


  • Diagnostic nerve blocks
  • Dynamic EMG
  • Rheologic properties of muscle
  • Spasticity
  • Spasticity pathophysiology
  • Stretch reflex
  • Upper motoneuron syndrome (UMN syndrome)


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