American Journal of Roentgenology, Vol 163, 1079-1082, Copyright © 1994 by American Roentgen Ray Society
Unilateral hyperlucent thorax on plain chest radiographs after neck dissection: importance of atrophy of the trapezius muscle
H Sugimoto and T Ohsawa
Department of Radiology, Jichi Medical School, Tochigi-ken, Japan.
OBJECTIVE. A hyperlucent thorax on plain chest radiography indicates a
decrease in the radiographic density of the thorax, which can be caused by
intra- or extrapulmonary diseases. The purpose of this study was to assess
the prevalence and mechanisms that may be responsible for unilateral
hyperlucency of the thorax after neck dissection and to determine if
atrophy of the trapezius due to the transection of the accessory nerve is a
cause of hyperlucent thorax. MATERIALS AND METHODS. Differences in the
radiographic density between the right and left lung were evaluated and
correlated with transection of the accessory nerve in 21 patients who had
had a radical or a modified neck dissection for a malignant tumor of the
head and neck. Twenty-eight neck dissections were performed on these 21
patients (seven had a simultaneous bilateral neck dissection). In 14 of the
21 patients, the accessory nerve had been severed during the neck surgery.
In six patients, mechanisms responsible for a hyperlucent thorax were
investigated with follow-up thoracic CT scans. RESULTS. In the radiographs,
eight patients had a hyperlucent thorax on the side of the neck dissection.
In all of these cases, the accessory nerve on the side of this neck
dissection had been severed during a radical or a modified neck dissection.
Prior to surgery, no such hyperlucency was noted. CT scans showed atrophy
of the denervated trapezius muscle. CONCLUSION. Our findings show that
atrophy of the denervated trapezius muscle after neck dissection is a cause
of unilateral hyperlucent thorax on plain chest radiographs. Therefore,
this finding should be anticipated as a postoperative change in patients
who have had this surgery.