Hyperactive tendon reflexes in spastic multiple sclerosis: Measures and mechanisms of action

Li-Qun Zhang*, Guangzhi Wang, Takashi Nishida, Xu Dali, James A Sliwa, William Z Rymer

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

47 Scopus citations


Objective: To develop new measures of tendon reflexes and evaluate hyperactive reflexes in patients with spastic multiple sclerosis (MS). Design: With the subject relaxed, a hand-held instrumented hammer was used to tap the patellar tendon and record the tapping force, while knee extension torque and quadriceps EMG were recorded isometrically as measures of the reflex response. Setting: Research laboratory in a rehabilitation hospital. Subjects: Ten spastic MS and 14 healthy subjects. Main Outcome Measures: Tendon tapping force (designated as system input), reflex torque (as output), their dynamic relationship (characterized as system parameters tendon reflex gain, contraction rate, and reflex loop delay), Ashworth scale, and tendon reflex scale. Results: The system parameters provide more repeatable measures than do input or output parameters alone because they quantify the input and output simultaneously and dynamically. Compared with control subjects, MS patients had a significantly lower threshold in tapping force (p = .026), yet their evoked reflex torque was significantly higher (p = .033). Despite significant quadriceps weakness (p < .0001), MS patients had a significantly higher reflex gain (p = .0002) and contraction rate (p = .0002), and shorter reflex loop delay (p = .0046), indicating hyperexcitability of motoneurons and peripheral receptors, and indicating that relatively more of the muscle was activated reflexively, with greater recruitment of larger fast-twitch fibers. Both the reflex gain and rate measures correlated more closely with the Ashworth scale and tendon reflex scale than did the output measures, indicating their potential clinical value. Conclusions: With appropriate simplification, the method may be used in clinical practice to quantify more precisely the tendon jerk than is currently feasible with standard clinical tests. (C) 2000 by the American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation.

Original languageEnglish (US)
Pages (from-to)901-909
Number of pages9
JournalArchives of Physical Medicine and Rehabilitation
Issue number7
StatePublished - Jan 1 2000


  • Multiple sclerosis
  • Reflex tendon
  • Rehabilitation

ASJC Scopus subject areas

  • Physical Therapy, Sports Therapy and Rehabilitation
  • Rehabilitation

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