Study Design. A prospective study.
Objective. To examine the diameter (mm), transverse diameter (mm), and cross-sectional area (mm2) of the C5, C6, and C7 nerve roots using ultrasonography.
Summary of Background Data. Each of the cervical nerve roots affected a different motor or sensory area. Although there were several studies that performed a detailed assessment of cervical nerve root anatomy in cadavers, only a few studies on the thickness of cervical nerve roots in living specimens have been performed. We examined whether the thickness of the C5, C6, and C7 nerve roots, as well as the area supplied by each of the roots, varied.
Methods. All 219 subjects (99 males and 120 females; mean age, 47 ± 15 yr) were healthy volunteers. The diameter and the transverse diameter were measured via ultrasonography, and the cross-sectional area was calculated for each of the C5–C7 nerve roots.
Results. The following diameter measurements (right and left, respectively) were obtained: C5, 2.8 and 2.9 mm; C6, 3.6 and 3.8 mm; and C7, 3.3 and 3.4 mm. The following transverse diameter measurements were obtained (right and left, respectively): C5, 2.8 and 3.0 mm; C6, 3.7 and 3.8 mm; and C7, 3.5 and 3.4 mm. The following cross-sectional area measurements (right and left, respectively) were obtained: C5, 6.3 and 6.4 mm2; C6, 10.7 and 11.0 mm2; and C7, 8.8 and 8.8 mm2. Based on the 3 measurement methods, the C5 nerve root was significantly thinner than the other 2 nerve roots (P < 0.001), and the C7 nerve root was smaller than the C6 nerve root (P = 0.001).
Conclusion. The C5 nerve root was significantly thinner than the C6 and C7 cervical nerve roots. The fact that the C5 nerve is thinner may render it more susceptible to damage during cervical surgery.
Level of Evidence: 2
The diameter and the transverse diameter at the C5, C6, and C7 cervical nerve roots were measured in 219 healthy subjects using ultrasonography. The C5 nerve root was significantly thinner than the other 2 nerve roots, which may be one reason why only C5 nerve damage occurs after cervical surgery.
From the Departments of *Spine Center
‡Orthopedic Surgery, Aichi Medical University, Nagakute, Aichi, Japan
§Department of General Surgery, Shirayama Surgical Clinic, Kasugai, Aichi, Japan; and
¶Department of Internal Medicine, Asai Hospital, Seto, Aichi, Japan.
Address correspondence and reprint requests to Mikinobu Takeuchi, MD, PhD, Department of Neurological Surgery, Aichi Medical University, Karimata 1-1 Yazako, Nagakute, Aichi Prefecture, 480-1195 Japan; E-mail: firstname.lastname@example.org
Acknowledgment date: December 12, 2013. First revision date: March 21, 2014. Second revision date: April 15, 2014. Acceptance date: April 20 2014.
The manuscript submitted does not contain information about medical device(s)/drug(s).
No funds were received in support of this work.
No relevant financial activities outside the submitted work.