The suboccipital ligament

Kelsey Alabaster, M. Fred Bugg, Bruno Splavski, Frederick Boop, Kenan I. Arnautovic

Research output: Contribution to journalArticle

2 Citations (Scopus)

Abstract

OBJECTIVE A fbrous structure located dorsal to the dura at the posterior craniocervical junction stretches horizontally between the bilateral occipital condyles and the upper borders of the C-1 laminae. Partially covered by the occipital bone, this structure is always encountered when the bone is removed from the foramen magnum rim during approaches to the posterior cranial fossa. Although known to surgeons, this structure has not been defned, studied, or named. The most appropriate name for this structure is "the suboccipital ligament," and a detailed rationale for this name is provided. METHODS This 3-year-long study included 10 cadaveric specimens and 39 clinical patients: 31 consecutive surgically treated patients with Chiari Type I malformations (CM-I subgroup) and 8 other patients with posterior fossa pathologies (non-CM-I subgroup). The dimensions were defned, the function of this ligament was hypothesized, size and histological composition were compared between patient subgroups, and its origin and relationship to the surrounding structures were analyzed. Possible statistical differences in the parameters between the 2 groups were also evaluated. RESULTS The suboccipital ligament consists of horizontally oriented hyaline fbers and has a median length of 35 mm, height of 10 mm, and thickness of 0.5 mm. These dimensions are not signifcantly different between the CM-I and non-CM-I patients. The median age of the patients was 43 years, with CM-I patients being signifcantly younger (median 35 years) than non-CM-I patients (median 57 years). There was no statistically signifcant difference in weight, height, and body mass index between patient subgroups. There was no signifcant correlation between the body mass index or height of the patients and the dimensions of the ligament. No statistically signifcant differences existed between the subgroups in terms of smoking history, alcohol consumption, and the presence of diabetes mellitus, hypertension, hydrocephalus, or headaches. The ligament tissue in the CM-I patients was disorganized with poorly arranged collagen bands and interspersed adipose tissue. These patients also had more hyalinized fbrosis and showed changes in the direction of fbers, with hyaline nodules ranging from 0 to 2+. The result of the histological evaluation of the suboccipital ligament for hyaline nodules, calcifcation, and ossifcation was graded as 2+ if present in 3 or more medium-power magnifcation felds (MPFs)∗1+ if present in 1-2 MPFs∗and 0, if present in less than 1 MPF. Histological examination of the ligaments showed structural differences between CM-I and non-CM-I patients, most notably the presence of hyaline nodules and an altered fber orientation in CM-I patients. CONCLUSIONS The suboccipital ligament extends between the occipital condyle and the superior edge of the C-1 lamina, connecting the contralateral sides, and appears to function as a real ligament. It is ventral to the occipital bone, which covers approximately two-thirds of the height of the ligament and is loosely attached to the dura medially and more frmly laterally. Because of its distinctive anatomy, characteristics, and function, the suboccipital ligament deserves its own uniform designation and name.

Original languageEnglish (US)
Pages (from-to)165-173
Number of pages9
JournalJournal of neurosurgery
Volume128
Issue number1
DOIs
StatePublished - Jan 1 2018

Fingerprint

Ligaments
Hyalin
Occipital Bone
Names
Bone and Bones
Body Mass Index
Arnold-Chiari Malformation
Foramen Magnum
Posterior Cranial Fossa
Hydrocephalus
Alcohol Drinking
Headache
Adipose Tissue
Anatomy
Diabetes Mellitus
Collagen
Smoking
History
Pathology

All Science Journal Classification (ASJC) codes

  • Surgery
  • Clinical Neurology

Cite this

Alabaster, K., Fred Bugg, M., Splavski, B., Boop, F., & Arnautovic, K. I. (2018). The suboccipital ligament. Journal of neurosurgery, 128(1), 165-173. https://doi.org/10.3171/2016.10.JNS162161

The suboccipital ligament. / Alabaster, Kelsey; Fred Bugg, M.; Splavski, Bruno; Boop, Frederick; Arnautovic, Kenan I.

In: Journal of neurosurgery, Vol. 128, No. 1, 01.01.2018, p. 165-173.

Research output: Contribution to journalArticle

Alabaster, K, Fred Bugg, M, Splavski, B, Boop, F & Arnautovic, KI 2018, 'The suboccipital ligament', Journal of neurosurgery, vol. 128, no. 1, pp. 165-173. https://doi.org/10.3171/2016.10.JNS162161
Alabaster K, Fred Bugg M, Splavski B, Boop F, Arnautovic KI. The suboccipital ligament. Journal of neurosurgery. 2018 Jan 1;128(1):165-173. https://doi.org/10.3171/2016.10.JNS162161
Alabaster, Kelsey ; Fred Bugg, M. ; Splavski, Bruno ; Boop, Frederick ; Arnautovic, Kenan I. / The suboccipital ligament. In: Journal of neurosurgery. 2018 ; Vol. 128, No. 1. pp. 165-173.
@article{63ba9849281841648bb0800981a8b0f1,
title = "The suboccipital ligament",
abstract = "OBJECTIVE A fbrous structure located dorsal to the dura at the posterior craniocervical junction stretches horizontally between the bilateral occipital condyles and the upper borders of the C-1 laminae. Partially covered by the occipital bone, this structure is always encountered when the bone is removed from the foramen magnum rim during approaches to the posterior cranial fossa. Although known to surgeons, this structure has not been defned, studied, or named. The most appropriate name for this structure is {"}the suboccipital ligament,{"} and a detailed rationale for this name is provided. METHODS This 3-year-long study included 10 cadaveric specimens and 39 clinical patients: 31 consecutive surgically treated patients with Chiari Type I malformations (CM-I subgroup) and 8 other patients with posterior fossa pathologies (non-CM-I subgroup). The dimensions were defned, the function of this ligament was hypothesized, size and histological composition were compared between patient subgroups, and its origin and relationship to the surrounding structures were analyzed. Possible statistical differences in the parameters between the 2 groups were also evaluated. RESULTS The suboccipital ligament consists of horizontally oriented hyaline fbers and has a median length of 35 mm, height of 10 mm, and thickness of 0.5 mm. These dimensions are not signifcantly different between the CM-I and non-CM-I patients. The median age of the patients was 43 years, with CM-I patients being signifcantly younger (median 35 years) than non-CM-I patients (median 57 years). There was no statistically signifcant difference in weight, height, and body mass index between patient subgroups. There was no signifcant correlation between the body mass index or height of the patients and the dimensions of the ligament. No statistically signifcant differences existed between the subgroups in terms of smoking history, alcohol consumption, and the presence of diabetes mellitus, hypertension, hydrocephalus, or headaches. The ligament tissue in the CM-I patients was disorganized with poorly arranged collagen bands and interspersed adipose tissue. These patients also had more hyalinized fbrosis and showed changes in the direction of fbers, with hyaline nodules ranging from 0 to 2+. The result of the histological evaluation of the suboccipital ligament for hyaline nodules, calcifcation, and ossifcation was graded as 2+ if present in 3 or more medium-power magnifcation felds (MPFs)∗1+ if present in 1-2 MPFs∗and 0, if present in less than 1 MPF. Histological examination of the ligaments showed structural differences between CM-I and non-CM-I patients, most notably the presence of hyaline nodules and an altered fber orientation in CM-I patients. CONCLUSIONS The suboccipital ligament extends between the occipital condyle and the superior edge of the C-1 lamina, connecting the contralateral sides, and appears to function as a real ligament. It is ventral to the occipital bone, which covers approximately two-thirds of the height of the ligament and is loosely attached to the dura medially and more frmly laterally. Because of its distinctive anatomy, characteristics, and function, the suboccipital ligament deserves its own uniform designation and name.",
author = "Kelsey Alabaster and {Fred Bugg}, M. and Bruno Splavski and Frederick Boop and Arnautovic, {Kenan I.}",
year = "2018",
month = "1",
day = "1",
doi = "10.3171/2016.10.JNS162161",
language = "English (US)",
volume = "128",
pages = "165--173",
journal = "Journal of Neurosurgery",
issn = "0022-3085",
publisher = "American Association of Neurological Surgeons",
number = "1",

}

TY - JOUR

T1 - The suboccipital ligament

AU - Alabaster, Kelsey

AU - Fred Bugg, M.

AU - Splavski, Bruno

AU - Boop, Frederick

AU - Arnautovic, Kenan I.

PY - 2018/1/1

Y1 - 2018/1/1

N2 - OBJECTIVE A fbrous structure located dorsal to the dura at the posterior craniocervical junction stretches horizontally between the bilateral occipital condyles and the upper borders of the C-1 laminae. Partially covered by the occipital bone, this structure is always encountered when the bone is removed from the foramen magnum rim during approaches to the posterior cranial fossa. Although known to surgeons, this structure has not been defned, studied, or named. The most appropriate name for this structure is "the suboccipital ligament," and a detailed rationale for this name is provided. METHODS This 3-year-long study included 10 cadaveric specimens and 39 clinical patients: 31 consecutive surgically treated patients with Chiari Type I malformations (CM-I subgroup) and 8 other patients with posterior fossa pathologies (non-CM-I subgroup). The dimensions were defned, the function of this ligament was hypothesized, size and histological composition were compared between patient subgroups, and its origin and relationship to the surrounding structures were analyzed. Possible statistical differences in the parameters between the 2 groups were also evaluated. RESULTS The suboccipital ligament consists of horizontally oriented hyaline fbers and has a median length of 35 mm, height of 10 mm, and thickness of 0.5 mm. These dimensions are not signifcantly different between the CM-I and non-CM-I patients. The median age of the patients was 43 years, with CM-I patients being signifcantly younger (median 35 years) than non-CM-I patients (median 57 years). There was no statistically signifcant difference in weight, height, and body mass index between patient subgroups. There was no signifcant correlation between the body mass index or height of the patients and the dimensions of the ligament. No statistically signifcant differences existed between the subgroups in terms of smoking history, alcohol consumption, and the presence of diabetes mellitus, hypertension, hydrocephalus, or headaches. The ligament tissue in the CM-I patients was disorganized with poorly arranged collagen bands and interspersed adipose tissue. These patients also had more hyalinized fbrosis and showed changes in the direction of fbers, with hyaline nodules ranging from 0 to 2+. The result of the histological evaluation of the suboccipital ligament for hyaline nodules, calcifcation, and ossifcation was graded as 2+ if present in 3 or more medium-power magnifcation felds (MPFs)∗1+ if present in 1-2 MPFs∗and 0, if present in less than 1 MPF. Histological examination of the ligaments showed structural differences between CM-I and non-CM-I patients, most notably the presence of hyaline nodules and an altered fber orientation in CM-I patients. CONCLUSIONS The suboccipital ligament extends between the occipital condyle and the superior edge of the C-1 lamina, connecting the contralateral sides, and appears to function as a real ligament. It is ventral to the occipital bone, which covers approximately two-thirds of the height of the ligament and is loosely attached to the dura medially and more frmly laterally. Because of its distinctive anatomy, characteristics, and function, the suboccipital ligament deserves its own uniform designation and name.

AB - OBJECTIVE A fbrous structure located dorsal to the dura at the posterior craniocervical junction stretches horizontally between the bilateral occipital condyles and the upper borders of the C-1 laminae. Partially covered by the occipital bone, this structure is always encountered when the bone is removed from the foramen magnum rim during approaches to the posterior cranial fossa. Although known to surgeons, this structure has not been defned, studied, or named. The most appropriate name for this structure is "the suboccipital ligament," and a detailed rationale for this name is provided. METHODS This 3-year-long study included 10 cadaveric specimens and 39 clinical patients: 31 consecutive surgically treated patients with Chiari Type I malformations (CM-I subgroup) and 8 other patients with posterior fossa pathologies (non-CM-I subgroup). The dimensions were defned, the function of this ligament was hypothesized, size and histological composition were compared between patient subgroups, and its origin and relationship to the surrounding structures were analyzed. Possible statistical differences in the parameters between the 2 groups were also evaluated. RESULTS The suboccipital ligament consists of horizontally oriented hyaline fbers and has a median length of 35 mm, height of 10 mm, and thickness of 0.5 mm. These dimensions are not signifcantly different between the CM-I and non-CM-I patients. The median age of the patients was 43 years, with CM-I patients being signifcantly younger (median 35 years) than non-CM-I patients (median 57 years). There was no statistically signifcant difference in weight, height, and body mass index between patient subgroups. There was no signifcant correlation between the body mass index or height of the patients and the dimensions of the ligament. No statistically signifcant differences existed between the subgroups in terms of smoking history, alcohol consumption, and the presence of diabetes mellitus, hypertension, hydrocephalus, or headaches. The ligament tissue in the CM-I patients was disorganized with poorly arranged collagen bands and interspersed adipose tissue. These patients also had more hyalinized fbrosis and showed changes in the direction of fbers, with hyaline nodules ranging from 0 to 2+. The result of the histological evaluation of the suboccipital ligament for hyaline nodules, calcifcation, and ossifcation was graded as 2+ if present in 3 or more medium-power magnifcation felds (MPFs)∗1+ if present in 1-2 MPFs∗and 0, if present in less than 1 MPF. Histological examination of the ligaments showed structural differences between CM-I and non-CM-I patients, most notably the presence of hyaline nodules and an altered fber orientation in CM-I patients. CONCLUSIONS The suboccipital ligament extends between the occipital condyle and the superior edge of the C-1 lamina, connecting the contralateral sides, and appears to function as a real ligament. It is ventral to the occipital bone, which covers approximately two-thirds of the height of the ligament and is loosely attached to the dura medially and more frmly laterally. Because of its distinctive anatomy, characteristics, and function, the suboccipital ligament deserves its own uniform designation and name.

UR - http://www.scopus.com/inward/record.url?scp=85039991930&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=85039991930&partnerID=8YFLogxK

U2 - 10.3171/2016.10.JNS162161

DO - 10.3171/2016.10.JNS162161

M3 - Article

VL - 128

SP - 165

EP - 173

JO - Journal of Neurosurgery

JF - Journal of Neurosurgery

SN - 0022-3085

IS - 1

ER -