Browsing by Author "Comert, Ayhan"

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The Cervical Arteries: an Anatomical Study With Application To Avoid the Nerve Root and Spinal Cord Blood Supply
(Turkish Neurosurgical Soc, 2018) Arslan, Mehmet; Acar, Halil Ibrahim; Comert, Ayhan; Tubbs, R. Shane
AIM: Injury to the vascular supply to the cervical spinal cord can lead to the anterior spinal artery syndrome, which is often associated with transforaminal corticosteroid injections to the cervical foramina. The purpose of this cadaveric study was to examine the morphology of the cervical arteries and to emphasize their clinical importance. MATERIAL and METHODS: Five formalin-fixed human cadavers were used to determine the morphology of the radicular arteries from the vertebral, ascending and deep cervical arteries in the cervical foraminal region. RESULTS: The mean diameter of the vertebral arteries was 5.50 mm. The radicular arteries arose from the vertebral artery originating from its posterior aspect at each level and the C6 radicular artery was larger in diameter than others. Their diameters ranged from 0.75 mm to 1.02 mm. The mean diameter of the ascending cervical artery was 1.5 mm (range 1.21 to 1.80 mm). Its arising spinal branches were located at the C3-4 or C4-5 levels. The diameters of radicular branches arising from the ascending cervical artery ranged from 0.80 mm to 1.40 mm. The mean diameter of the deep cervical artery was 1.71 mm (range 1.3 to 2.1 mm) and was usually slightly larger than the ascending cervical arteries. These deep cervical radicular arteries always entered the C5-6, C6-7 and C7-T1 foramens and those of the radicular branches arising from the deep cervical artery ranged from 0.43 mm to 1.49 mm (mean, 1.08 mm). CONCLUSION: Understanding the vascular supply to the cervical spinal cord is important for preventing serious complications such as spinal cord ischemia.
Cervical Extraforaminal Ligaments: an Anatomical Study
(Springer France, 2017) Arslan, Mehmet; Acar, Halil Ibrahim; Comert, Ayhan
The purpose of this study was to elucidate the anatomy and clinical importance of extraforaminal ligaments in the cervical region. This study was performed on eight embalmed cadavers. The existence and types of extraforaminal ligaments were identified. The morphology, quantity, origin, insertion, and orientation of the extraforaminal ligaments in the cervical region were observed. Extraforaminal ligaments could be divided into two types: transforaminal ligaments and radiating ligaments. It was observed that during their course, transforaminal ligaments cross the intervertebral foramen ventrally. They usually originate from the anteroinferior margin of the anterior tubercle of the cranial transverse process and insert into the superior margin of the anterior tubercle of the caudal transverse process. The dorsal aspect of the transforaminal ligaments adhere loosely to the spinal nerve sheath. The length, width and thickness of these ligaments increased from the cranial to the caudal direction. A single intervertebral foramen contained at least one transforaminal ligament. A total of 98 ligaments in 96 intervertebral foramina were found. The spinal nerves were extraforaminally attached to neighboring anterior and posterior tubercle of the cervical transverse process by the radiating ligaments. The radiating ligaments consisted of the ventral superior, ventral, ventral inferior, dorsal superior and dorsal inferior radiating ligaments. Radiating ligaments originated from the adjacent transverse processes and inserted into the nerve root sheath. The spinal nerve was held like the hub of a wheel by a series of radiating ligaments. The dorsal ligaments were the thickest. From C2-3 to C6-7 at the cervical spine, radiating ligaments were observed. They developed particularly at the level of the C5-C6 intervertebral foramen. This anatomic study may provide a better understanding of the relationship of the extraforaminal ligaments to the cervical nerve root.
Lumbosacral Intrathecal Nerve Roots: an Anatomical Study
(Springer Wien, 2011) Arslan, Mehmet; Comert, Ayhan; Acar, Halil Ibrahim; Ozdemir, Mevci; Elhan, Alaittin; Tekdemir, Ibrahim; Ugur, Hasan Caglar
Background The lumbosacral intrathecal anatomy is complex because of the density of nerve roots in the cauda equina. Space-occupying lesions, including disc herniation, trauma and tumor, within the spinal canal may compromise the nerve roots, causing severe clinical syndromes. The goal of this study is to provide spinal surgeons with a detailed anatomical description of the intrathecal nerve roots and to emphasize their clinical importance. Method Ten formalin-fixed male cadavers were studied. They were dissected with the aid of a surgical microscope, and measurements were performed. Results The number of dorsal and ventral roots ranged from one to three. The average diameter of roots increased from L1 to S1 (0.80 mm for L1 and 4.16 for S1), respectively. Then their diameter decreased from S1 to S5 (4.16 mm for S1, 0.46 mm for S5). The largest diameter was found at S1 and the smallest at S5. The average number of rootlets per nerve root increased from L1 to S1, then decreased (3.25 for L1, 12.6 for S1, and 1.2 for S5), respectively. The greatest rootlet number was seen at S1, and the fewest were observed at S5. The average diameter of the lateral recess gradually decreased from L1 to L4 (9.1 mm for L1; 5.96 mm for L4) and then increased at L5 level (6.06 mm); however, the diameter of the nerve root increased from L1 to L5. The midpoint of distance between the superior and inferior edge of the intradural exit nerve root was 3.47 mm below the inferior edge of the superior articular process at the L1 level, while the origin of the L5 exit root was 5.75 mm above the inferior edge. The root origin gradually ascended from L1 to L5. Conclusions The findings of this study may be valuable for understanding lesions compressing intradural nerve roots and may be useful for intradural spinal procedures.
Lumbosacral Intrathecal Nerve Roots: an Anatomical Study
(Springer Wien, 2013) Arslan, Mehmet; Comert, Ayhan; Acar, Halil Ibrahim; Ozdemir, Mevci; Elhan, Alaittin; Tekdemir, Ibrahim; Ugur, Hasan Caglar
Nerve Root To Lumbar Disc Relationships at the Intervertebral Foramen From a Surgical Viewpoint: an Anatomical Study
(Wiley, 2012) Arslan, Mehmet; Comert, Ayhan; Acar, Halil Ibrahim; Ozdemir, Mevci; Elhan, Alaittin; Tekdemir, Ibrahim; Ugur, Hasan Caglar
The objective of this study was to analyze relationship of the intervertebral disc to the nerve root in the intervertebral foramen. Fourteen formalin-fixed cadavers were studied and measurements were performed. At the medial line of the neural foramen, the disc-root distance gradually increased from L1-L2 to L5-S1. The shortest distance between the disc to nerve root was L1-L2 (mean, 8.2 mm) and the greatest distance was found at L3-L4 (mean, 10.5 mm). In the mid-foramen, the disc-root distance decreased from L1-2 to L5-S1. The shortest distance from the disc to nerve root was found at L5-S1 (mean, 0.4 mm); and the greatest distance, at L1-L2 (mean, 3.8 mm). For the lateral line, the distance between an intersection point between the medial edge of the nerve root and the superior edge of the disc and lateral line of the foramen consistently increased from L1-L2 to L5-S1. The shortest distance from nerve root to the lateral border of the foramen, at the point where the nerve root crosses disc was at level L1-L2 (mean, 2.6 mm), the greatest distance, L5-S1 (mean, 8.8 mm). The width of the foramina progressively increased in a craniocaudal direction (mean, 8.317.8 mm from L1-2 to L5-S1, respectively). The mean height of the foramina was more or less the same for disc levels (range, 19.321.5). The results showed that nerve roots at lower levels traveled closer to the midline of the foramen. This morphometric information may be helpful in minimizing the incidence of injury to the lumbar nerve root during foraminal and extraforaminal approaches. Clin. Anat. 25:218223, 2012. (C) 2011 Wiley-Liss, Inc.
Neurovascular Structures Adjacent To the Lumbar Intervertebral Discs: an Anatomical Study of Their Morphometry and Relationships
(Amer Assoc Neurological Surgeons, 2011) Arslan, Mehmet; Comert, Ayhan; Acar, Halil Ibrahim; Ozdemir, Mevci; Elhan, Alaittin; Tekdemir, Ibrahim; Ugur, Hasan Caglar
Object. Although infrequent, injury to adjacent neurovascular structures during posterior approaches to lumbar intervertebral discs can occur. A detailed anatomical knowledge of relationships may decrease surgical complications. Methods. Ten formalin-fixed male cadavers were used for this study. Posterior exposure of the lumbar thecal sac, nerve roots, pedicles, and intervertebral discs was performed. To identify retroperitoneal structures at risk during posterior lumbar discectomy, a transabdominal retroperitoneal approach was performed, and observations were made. The distances between the posterior and anterior edges of the lumbar intervertebral discs were measured, and the relationships between the disc space, pedicle, and nerve root were evaluated. Results. For right and left sides, the mean distance from the inferior pedicle to the disc gradually increased from L1-2 to L4-5 (range 2.7-3.8 mm and 2.9-4.5 mm for right and left side, respectively) and slightly decreased at L5-S1. For right and left sides, the mean distance from the superior pedicle to the disc was more or less the same for all disc spaces (range 9.3-11.6 mm and 8.2-10.5 mm for right and left, respectively). The right and left mean disc-to-root distance for the L3-4 to L5-S1 levels ranged from 8.3 to 22.1 mm and 7.2 to 20.6 mm, respectively. The root origin gradually increased from L-1 to L-5. The right and left nerve root to-disc angle gradually decreased from L-3 to S-1 (range 105 degrees-110.6 degrees and 99 degrees-108 degrees). Disc heights gradually increased from L1-2 to L5-S1 (range 11.3-17.4 mm). The mean distance between the anterior and posterior borders of the intervertebral discs ranged from 39 to 46 mm for all levels. Conclusions. To avoid neighboring neurovascular structures, instrumentation should not be inserted into the lumbar disc spaces more than 3 cm from their posterior edge. Accurate anatomical knowledge of the relationships of intervertebral discs to nerve roots is needed for spine surgeons. (DOI: 10.3171/2010.11.SPINE09149)
Relationship of Dorsal Root Ganglion To Intervertebral Foramen in Lumbar Region: an Anatomical Study and Review of Literature
(Edizioni Minerva Medica, 2016) Silav, Gokalp; Arslan, Mehmet; Comert, Ayhan; Acar, Halil I.; Kahilogullari, Gokmen; Dolgun, Habibullah; Tekdemir, Ibrahim
BACKGROUND: The purpose of this study was to clarify the morphologic features, location and variations of the dorsal root ganglion (DRG). METHODS: Fifteen formalin fixed cadavers for the current study were included. Total of 150 DRGs were examined from L1 to L5. The relationships of the nerve root DRGs to the intervertebral foramen were noted. Position of the DRG was classified by the location of the ganglia in relation to the pedicle. The relationship of the DRG to the intervertebral foramen was evaluated. RESULTS: The distance between the midpoint of the DRG to the cross section of the root with the medial border of the pedicle gradually increased from L1 to L5. The medial border of the foramen distances along the nerve root were L1, 1.77 mm; L2, 2.79 mm; L3, 3.23 mm; L4, 7.28 mm and L5, 8.31 mm. The mean width of the lumbar DRGs were L1, 4.36 mm; L2, 4.56 mm; L3, 4.99 mm; L4, 5.22 mm and L5, 5.82 mm. The mean length of DRGs were as follows: L1, 5.39 mm; L2, 5.83 mm; L3, 7.24 mm; L4, 7.97 nun and L5, 10.83 mm. The mean width and length of DRGs gradually increased from Ll to L5. CONCLUSIONS: The DRG in the lumbar region play a key role in the occurence of low-back pain and sciatica; therefore, it is important to understand the anatomy of DRG. The accurate anatomic information about the position of DRGs would be useful to perform a safe surgical intervention in the lumbar foraminal region.
Surgical View of the Lumbar Arteries and Their Branches: an Anatomical Study
(Lippincott Williams & Wilkins, 2011) Arslan, Mehmet; Comert, Ayhan; Acar, Halil Ibrahim; Ozdemir, Mevci; Elhan, Alaittin; Tekdemir, Ibrahim; Ugur, Hasan Caglar
BACKGROUND: Although injury to the lumbar arteries during anterior spinal approaches is often encountered, there are few published articles regarding the relationship between the lumbar arteries and spinal cord ischemia. OBJECTIVE: To examine the morphology of the lumbar arteries and to emphasize their clinical importance. METHODS: With the aid of a surgical microscope, 80 lumbar arteries in 10 formalin-fixed male cadavers were studied. Measurements of these structures were made and relationships observed. RESULTS: The spinal artery was usually the first branch of the lumbar artery. The greatest lumbar artery diameter was at L4 and had a mean diameter of 3.25 mm; the smallest diameter was identified at L2 and had a mean diameter of 2.05 mm. The largest spinal artery diameter was at L3 (mean, 0.56 mm) and the smallest at L1 (mean, 0.42 mm). The largest anastomotic artery diameter was at L4 (mean, 0.42 mm) and the smallest at L1 (mean, 0.32 mm). For the right and left sides, the mean greatest distance between the origin of the lumbar artery and the tendinous arch was at L4 (mean, 40.9 and 31.8 mm, respectively) and the least at L1 (mean, 31.8 and 22.5 mm, respectively). The mean of the greatest distance between the anastomotic branch and the base of the transverse process of the lumbar vertebrae was at L4 (mean, 4.41 and 4.35 mm, respectively) and the smallest at L1 (mean, 4.04 and 4.08 mm, respectively). CONCLUSION: These anatomic findings of the lumbar segmental arteries would be useful for emphasizing their surgical importance.