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J Neurol (2014) 261:13401343 DOI 10.1007/s00415-014-7329-4
ORIGINAL COMMUNICATION
The tibialis anterior response revisited
Alexander C. Lehn Sasha Dionisio
Caroline A. Airey Helen Brown Stefan Blum
Robert Henderson
Received: 28 February 2014 / Revised: 23 March 2014 / Accepted: 24 March 2014 / Published online: 24 April 2014 Springer-Verlag Berlin Heidelberg 2014
Abstract The idiomuscular response to direct percussion is rarely tested nowadays because of its uncertain mechanism and signicance. While performing neurological examination, we observed a brisk ankle dorsiexion response on direct muscle percussion of m. tibialis anterior in patients with acute inammatory demyelinating polyradiculoneuropathy (AIDP). In contrast, in patients with upper motor neuron lesions, an ankle inversion response was seen. In this article we describe our ndings in patients with bilateral lower limb weakness. We assessed 73 consecutive patients with bilateral lower limb weakness. A strong dorsiexion response to percussion of m. tibialis anterior was seen in 11 out of 14 patients with AIDP (sensitivity 78.6 %). None of the other patients showed a strong dorsiexion response (specicity 100 %). An inversion response was seen in 11 out of 13 patients with UMN involvement (sensitivity 92.3 %). It was also noted in two of 46 patients without proven UMN involvement (specicity 96.7 %). The idiomuscular response to percussion of m. tibialis anterior can be useful in the assessment of patients with lower limb weakness of unclear cause.
Keywords Percussion GuillainBarr syndrome
Spasticity Clinical examination
Introduction
In 1858 the German physiologist Moritz Schiff described what he called idiomuskulare contraction (idiomuscular contraction), the activation of skeletal muscle after direct percussion [1]. Twenty-three years later in his monograph, The diagnosis of diseases of the spinal cord, Gowers described a phenomenon he named front-tap contraction seen in patients with spasticity where percussion of the muscles on the front of the leg causes ankle dorsiexion [2]. This response has been described as diminished in myopathies, but increased in neuropathies [3]. More recently, it has been linked to conduction block [4, 5]. Today, the idiomuscular response to percussion is rarely tested because of its uncertain mechanism and signicance.
Whilst performing neurological examination, we observed a brisk ankle dorsiexion response on direct muscle percussion of m. tibialis anterior in patients with acute inammatory demyelinating polyradiculoneuropathy (AIDP). In contrast, in patients with...