R. Shane Tubbs, Marios Loukas, Mohammadali M. Shoja, Mohammad R. Ardalan, Nihal Apaydin, Candice Myers, Ghaffar Shokouhi and W. Jerry Oakes
The intradural contributions of the C-4 nerve rootlets have not been previously evaluated for their connections to the brachial plexus. The authors undertook a cadaveric study to evaluate the C-4 contributions to the upper trunk of the brachial plexus.
The posterior cervical triangles from 60 adult cadavers were dissected. All specimens that were found to have extradural C-4 contributions to the upper trunk of the brachial plexus were excluded from further study. In specimens found to have no extradural C-4 contributions to the brachial plexus a C1–T1 laminectomy was performed. Observations were made of any neural communications between adjacent spinal rootlets, specifically between C-4 and C-5.
Nine (15%) of the 60 sides were found to have extradural C-4 contributions to the upper trunk of the brachial plexus. These sides were excluded from further study. No specimen was found to have a postfixed brachial plexus. Of the remaining 51 sides, 11 (21.6%) were found to have intradural neural connections between C-4 and C-5 dorsal rootlets and 1 (1.96%) had a connection between the ventral roots of C-4 and C-5. Communications between these 2 adjacent dorsal cervical cord levels were of 3 types. Type I was a vertical communication between the more horizontally traveling dorsal roots. Type II was a forked communication between adjacent C-4 and C-5 dorsal rootlets. The Type III designation was applied to connections between ventral rootlets. Although communications were slightly more frequent on left sides, this did not reach statistical significance.
In ~ 20% of normally composed brachial plexuses (those with extradural contributions from only C5–T1) we found intradural C4–5 neural connections. Such variations may lead to misinterpretation of spinal levels in pathological conditions of the spinal axis and should be considered in surgical procedures of this region, such as rhizotomy.
R. Shane Tubbs, Marios Loukas, Mohammadali M. Shoja, Nihal Apaydin, Mohammad R. Ardalan and W. Jerry Oakes
There is scant and conflicting information in the literature regarding the lateral lacunae, or lateral lakes of Trolard. As these venous structures can be encountered surgically, this study aimed at further elucidating their anatomy, identifying surgical landmarks, and associated quantitation.
Thirty-five adult cadavers were dissected of lateral lacunae. Following quantitation of the lacunae, these structures were measured, as were the distances from them to the coronal and sagittal sutures.
A mean of 1.9 lacunae were identified on the right sides and 1.4 lacunae on the left sides. Although there tended to be slightly more lacunae on the right sides, this difference did not reach statistical significance (p > 0.05). The average lengths of the lacunae were 3.2 and 2.0 cm for the right and left sides, respectively. The mean widths of these venous lakes were 1.5 cm for the right sides and 0.8 cm for the left sides. Lacunae were variably positioned but tended to cluster near the vertex of the skull. None were identified posterior to the lambdoid sutures, and only 5 were found to lie anterior to the coronal suture, with 4 of these located on right sides (p < 0.05). When lacunae were identified anterior to the coronal suture, they were generally 5–6 cm from this structure. The majority of lacunae could be identified between the coronal and lambdoid sutures and within 3 cm of the midline.
Although the situation varies, lateral lacunae are concentrated posterior to the coronal suture and anterior to the lambdoid sutures. They are most often found within 3 cm of the sagittal suture. These previously unreported data could be useful to the neurosurgeon in planning surgical procedures that traverse the calvaria.