The Leg Drop Pendulum Test performed under general anesthesia in spastic cerebral palsy

Abstract

The general aim of this study was to examine the stiffness and damping characteristics (rate at which oscillations diminish) of limbs of a small population of patients with spastic cerebral palsy (CP) during the Leg Drop Pendulum Test while under general anesthesia and to compare them with patients without CP, both awake and under similar anesthetized conditions. To facilitate a quantitative comparison the authors defined a set of parameters that reflect the stiffness and damping of limbs with spasticity under general anesthesia. To give these parameters more meaning a similar set was constructed for children without disabilities under conditions of normal wakefulness and under anesthesia. The test population of 10 patients with spasticity ranged in age from 4 to 19 years and had a mean age of 10 years 9 months (SD 5 years 10 months); there were four females and six males. The control population consisted of eight patients without disabilities who ranged in age from 7 to 19 years with mean age of 13 years 9 months (SD 3 years 3 months); there were six females and two males. To even out the populations, two limbs from the non-affected sides of two patients with hemiplegic spasticity (both female) were used in the control group. The Leg Drop Pendulum Test was administered to 10 limbs with spastic CP and 10 control limbs under general anesthesia. The two test populations were chosen from patients who were previously scheduled to undergo surgery. Two measures compared limbs of those under anesthetic with those under alert conditions: the damped natural frequency and the damping ratio. The natural frequency is the frequency at which a pendulum oscillates as it comes to rest; the damping ratio is a measure of how quickly the oscillations diminish. In spasticity, active muscle tone disappeared under anesthesia. In both groups the underlying biomechanics of the limb varied considerably. In controls the variation seemed to be growth related.

An admittance shaping controller for exoskeleton assistance of the lower extremities

“…The passive stiffness of the hip joint can be estimated with reasonable accuracy under highly controlled conditions (Fee and Miller 2004). However, hip impedance also has reflexive components due to muscle activation (Schouten et al 2008).…”

Reliability of the three-dimensional pendulum test for able-bodied children and children diagnosed with cerebral palsy

“…Increased tone/ spasticity of the rectus femoris, hamstrings and gastrocsoleus muscle groups are often associated with causing impaired walking and transfer abilities for children diagnosed with CP [1][2][3]. Numerous potential interventions can be used to treat spasticity in children with CP.…”

“…Children with the primary diagnosis of cerebral palsy (CP) often present with gross motor limitations resulting in decreased ability to walk and transfer [1]. Increased tone/ spasticity of the rectus femoris, hamstrings and gastrocsoleus muscle groups are often associated with causing impaired walking and transfer abilities for children diagnosed with CP [1][2][3].…”

“…The knee motions occurring during the pendulum test have been quantitatively measured using electrogoniometers [9], onedimensional video analysis [10], magnetic tracking system [1], and three-dimensional motion analysis system [11]. The main focus of these three studies was to present the methodology of measuring the knee motions using each technology [9][10][11].…”

Quantifying the mechanical work of resting quadriceps muscle tone

“…Resting muscle MMG activity likewise decreases with neuromuscular blockade (McKay et al 1998). Muscle tone has been quantified by instrumented models of the Wartenberg test, a test of muscle tone that depends upon allowing the relaxed leg to drop freely from the horizontal position and studying the movement that results (Fee and Miller 2004;Wartenberg 1951). Because it is the most direct approach to measurement of muscle force, we used a modification of the instrumented Wartenberg test applied to the leg-quadriceps unit that studies only the time it takes for the foot to land on a pillow 16 cm below the horizontal.…”