CMT 1A: Conduction velocity of the human phrenic nerve in the neck

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J Electromyogr Kinesiol. 2007 Sep 19

Conduction velocity of the human phrenic nerve in the neck.

Morélot-Panzini C, Fournier E, Donzel-Raynaud C, Dubourg O, Willer

JC, Similowski T.

Assistance Publique-Hôpitaux de Paris, Groupe Hospitalier Pitié-

Salpêtrière, Laboratoire de Physiopathologie Respiratoire du Service

de Pneumologie et Réanimation, Paris, France; UPRES EA2397,

Université Paris VI Pierre et Marie Curie, Paris, France; Assistance

Publique-Hôpitaux de Paris, Groupe Hospitalier Pitié-Salpêtrière,

Département de Neurophysiologie Clinique, Paris, France.

PURPOSE: To measure phrenic nerve conduction velocity in the neck in

humans.

SCOPE: We studied 15 healthy subjects (9 men, 32.4+/-6.7). We

performed bipolar electrical phrenic stimulation in the neck, from a

distal and a proximal stimulation site, and recorded diaphragm

electromyographic responses on the surface of the chest. The ratio

of the between-site distance to the latency difference provided

phrenic velocities. Ulnar motor velocity was assessed similarly. In

addition, five homogeneous patients with Charcot-Marie-Tooth disease

type 1A (CMT1A) were studied for validation purposes. We obtained

diaphragmatic responses from the two stimulation sites in all cases.

The distal latencies (anterior axillary line recording) were 6.51+/-

0.63ms (right) and 6.13+/-0.64ms (left). The minimal between site

distance was 39mm. Phrenic motor velocity was 55.2+/-6.3ms(-1)

(right) and 56.3+/-7.2ms(-1) (left). In CMT1A, phrenic velocities

were 17.1+/-8.1ms(-1) (from 7 to 32ms(-1)) and were similar to ulnar

and median velocities.

CONCLUSIONS: Phrenic nerve velocities can be estimated in humans and

compare with upper limb motor conduction velocities. This should

refine the investigation of phrenic function in peripheral

neuropathies.