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Estudo anatômico do trajeto da artéria vertebral na coluna cervical inferior humana

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Abstract

SUMMARY The increasing use of new techniques and materials for surgical treatment of lower cervical spine conditions has come along with an increasing concern regarding potential complications that might occur. The transpedicular fixation technique, frequently used in other spine levels, is used on the cervical spine, while providing more stability than other techniques, it may cause serious complications such as vertebral artery injury, nervous root injury, or facet joint in- juries. However, the C7 vertebra is considered safer for performing this procedure, since, in the vast majority of people, according to available anatomical studies, does not have a vertebral artery passing through its cross-sectional foramen, because that vessel is inserted into such structure only on C6 vertebra. As there are only imaging studies available today for assessing the path of this artery and its anatomical variables, we conducted this anatomical study by dissecting 40 cadaver's vertebral arteries in order to assess the incidence of anatomical variations. We found 3 cases where the vertebral artery penetrated into cross-sectional foramen at C7 (7.5%), a fact that enhances the risk of an undesired injury with a transpedicular technique at this level. The other remaining specimens showed a usual anatomy.
84 ACTA ORTOP BRAS 15(2: 84-86, 2007)
Trabalho recebido em 15/09/06 aprovado em 20/09/06
ARTIGO ORIGINAL
RESUMO
O aumento da utilização de novas técnicas e materiais de síntese
para o tratamento cirúrgico de afecções da coluna cervical baixa foi
acompanhado da crescente preocupação em relação às complica-
ções que podem ocorrer. A técnica de fixação transpedicular, am-
plamente utilizada para os outros níveis da coluna vertebral, quando
realizada na coluna cervical, apesar de conferir maior estabilidade
quando comparada a outras técnicas, pode cursar com complica-
ções graves como lesão da artéria vertebral, lesão de raiz nervosa,
além de lesão da articulação facetária. A vértebra C7, no entanto, é
considerada mais segura para a realização de tal procedimento, já
que, na grande maioria das pessoas, segundo os estudos anatô-
micos disponíveis, esta não possui a artéria vertebral dentro de seu
forame transverso, pois este vaso irá penetrar tal estrutura apenas
na vértebra C6. Como hoje existem apenas estudos de imagem
para avaliação do trajeto desta artéria e suas variações anatômicas,
realizamos este estudo anatômico dissecando 40 artérias vertebrais
de cadáveres para avaliar a incidência das variações anatômicas.
Encontramos 3 casos onde a artéria vertebral penetrou o forame
transverso já em C7 (7,5%), o que aumentaria o risco de uma téc-
nica transpedicular neste nível. O restante das peças anatômicas
possuíam anatomia habitual.
Descritores: Artéria vertebral; Coluna vertebral/anatomia &
histologia; Cadáver.
ESTUDO ANATÔMICO DO TRAJETO DA ARTÉRIA
VERTEBRAL NA COLUNA CERVICAL INFERIOR HUMANA
Ben Hur Junitiro Kajimoto1, Renato Luis Dainesi Addeo1, Gustavo Constantino de Campos1, Douglas Kenji Narazaki2,
Leonardo dos Santos Correia2, Marcelo Poderoso de Araújo3, Alexandre Fogaça Cristante4, Alexandre Sadao Iutaka4,
Raphael Martus Marcon5, Reginaldo Perilo Oliveira6, Tarcísio Eloy Pessoa de Barros Filho7
INTRODUÇÃO
A estabilização posterior da coluna cervical é comumente utilizada
para o tratamento de uma coluna cervical instável resultante de trau-
ma, neoplasia, condições degenerativas ou falha de uma artrodese
anterior. Tal procedimento é freqüentemente realizado com o uso
de parafusos de massas laterais ou amarrilhos interespinhosos ou
sublaminares. Estas técnicas nem sempre fornecem estabilidade
suficiente, sendo algumas vezes necessário acrescentar secunda-
riamente procedimentos de estabilização anterior(1).
Recentemente, a técnica de fixação transpedicular tem sido intro-
duzida como alternativa de se obter fixação estável por via posterior
sem a necessidade de uma eventual abordagem por via anterior(1-4).
Panjabi et al publicou o primeiro estudo anatômico tridimensional no
qual demonstrou a capacidade dos pedículos das vértebras cervi-
cais humanas em permitirem a fixação transpedicular(5,6). Kotani et
al demonstrou, em estudos com cadáveres humanos, que a fixação
transpedicular oferece maior estabilidade, comparado a métodos
tradicionais de fixação, tanto anterior quanto posterior, em lesões
cervicais acometendo duas ou três colunas e em instabilidades
cervicais de múltiplos níveis(5,7).
Com a popularização desta técnica houve um aumento na incidên-
cia de complicações tais como lesão da artéria vertebral, lesão de
raiz nervosa e da articulação facetária(1,8).
Para a colocação bem sucedida do parafuso pedicular na coluna
cervical é necessário conhecimento da anatomia do pedículo para
determinar o eixo de introdução do parafuso(5,9-11). Desvios mínimos
neste eixo acarretam em violação da parede do pedículo, o que
pode resultar em significante lesão neurológica ou vascular(5,11).
Estudos recentes mostram que a violação da parede lateral do
ANATOMICAL STUDY OF THE VERTEBRAL ARTERY PATH IN HUMAN LOWER CERVICAL SPINE
SUMMARY
The increasing use of new techniques and materials for surgical
treatment of lower cervical spine conditions has come along with
an increasing concern regarding potential complications that might
occur. The transpedicular fixation technique, frequently used in other
spine levels, is used on the cervical spine, while providing more
stability than other techniques, it may cause serious complications
such as vertebral artery injury, nervous root injury, or facet joint in-
juries. However, the C7 vertebra is considered safer for performing
this procedure, since, in the vast majority of people, according
to available anatomical studies, does not have a vertebral artery
passing through its cross-sectional foramen, because that vessel
is inserted into such structure only on C6 vertebra. As there are
only imaging studies available today for assessing the path of this
artery and its anatomical variables, we conducted this anatomical
study by dissecting 40 cadaver’s vertebral arteries in order to
assess the incidence of anatomical variations. We found 3 cases
where the vertebral artery penetrated into cross-sectional foramen
at C7 (7.5%), a fact that enhances the risk of an undesired injury
with a transpedicular technique at this level. The other remaining
specimens showed a usual anatomy.
Keywords: Vertebral artery; Spine/anatomy & histology;
Cadaver.
Citação: Kajimoto BHJ, Addeo RLD, Campos GC, Narazaki DK, Correia LS, Araújo
MP, et al. Estudo anatômico do trajeto da artéria vertebral na coluna cervical inferior
humana. Acta Ortop Bras. [periódico na Internet]. 2007; 15(2):84-86. Disponível
em URL: http://www.scielo.br/aob.
Citation: Kajimoto BHJ, Addeo RLD, Campos GC, Narazaki DK, Correia LS, Araújo
MP, et al. Anatomical study of the vertebral artery path in human lower cervical spine.
Acta Ortop Bras. [serial on the Internet]. 2007; 15(2): 84-86 . Available from URL:
http://www.scielo.br/aob.
Trabalho realizado no Departamento de Coluna do Instituto de Ortopedia e Traumatologia
Endereço para correspondência: Gustavo Constantino de Campos, Rua Arruda Alvin, apto.33 – Pinheiros - São Paulo – SP - Brasil - CEP: 05410-020 - Email: gustavoccampos@terra.com.br
1. Residente em Ortopedia e Traumatologia da FMUSP
2. Estagiário do Serviço de Coluna do Instituto de Ortopedia e Traumatologia da FMUSP
3. Médico Preceptor do Instituto de Ortopedia e Traumatologia da FMUSP
4. Médico Assistente do Instituto de Ortopedia e Traumatologia da FMUSP
5. Mestre em Ortopedia e Traumatologia pela FMUSP
6. Doutor em Ortopedia e Traumatologia pela FMUSP e Chefe do Grupo de Coluna do IOT HCFMUSP
7. Professor Titular da Disciplina de Ortopedia e Traumatologia da Faculdade de Medicina da USP
85
ACTA ORTOP BRAS 15 (2: 84-86, 2007)
pedículo é o acidente mais freqüente na introdução do parafuso
pedicular, colocando em risco a artéria vertebral(1). Com a lesão
da artéria vertebral na região cervical, o paciente que apresenta
débito sanguíneo inadequado pela artéria contralateral (por oclusão
arterosclerótica, p ex), poderá sofrer infarto medular lateral, situação
esta referida como síndrome de Wallenberg, que se caracteriza por
déficit sensitivo à dor na face ipsolateral e membros contralaterais,
nistagmo, ataxia, dismetria no membro ipsolateral, miose e ptose
ipsolaterais(9).
De acordo com descrições clássicas anatômicas, a artéria vertebral
origina-se na artéria subclávia, e sobe anteriormente ao processo
transverso da sétima vértebra cervical, portanto lateral ao forame
transverso neste nível, penetrando o forame transverso da sexta
vértebra cervical e fazendo trajeto ascendente sempre através dos
forames transversos até a primeira vértebra cervical. Em seguida,
corre póstero-lateralmente à primeira vértebra e entra no forame
magno. O forame transverso das vértebras cervicais situa-se la-
teralmente ao corpo da vértebra, à frente da massa lateral e logo
anterior a raiz nervosa(12-14). Variações anatômicas no percurso da
artéria no seguimento entre a segunda e sexta vértebras são raras.
Frente a tal anatomia, é considerado seguro o uso de parafusos
pediculares apenas na sétima vértebra cervical(5), na qual, normal-
mente, a artéria vertebral não está presente no forame transverso.
Porém, em uma pequena parte da população, a artéria vertebral
é encontrada dentro do forame transverso da sétima vértebra
cervical. De acordo com levantamentos bibliográficos, trabalhos
anatômicos que definam a incidência em que a artéria vertebral
está presente no interior do forame transverso de C7 na nossa
população são inexistentes.
Nosso estudo tem o objetivo de investigar a relação da artéria ver-
tebral e o forame transverso da sétima vértebra cervical em nosso
meio, com a finalidade de colaborar para a avaliação do risco do
uso do parafuso pedicular na coluna cervical.
MATERIAL E MÉTODO
Para a realização deste estudo foram estudadas 40 artérias ver-
tebrais cervicais em 20 cadáveres provenientes do Serviço de
Verificação de Óbitos da Universidade de São Paulo, escolhidos
aleatoriamente. Neles, expôs-se o trajeto da artéria vertebral a
partir da primeira vértebra torácica até a sexta vértebra cervical,
observando o ponto em que ela assume posição dentro do forame
transverso.
O Critério de inclusão utilizado foi a maturidade esquelética do
espécime, considerada atingida para os cadáveres com idade
superior a 18 anos. Os critérios de exclusão foram:
a- deformidades ósseas no segmento cervical, visíveis após o
posicionamento do cadáver em decúbito ventral;
b- cicatrizes de pele na região cervical dorsal sugestivas de cirurgia
prévia de coluna;
c- mal-formações vertebrais visualizadas durante a dissecção;
d- fraturas dos processos transversos ou outras proeminências
ósseas relevantes durante a dissecção;
Cada cadáver foi posicionado em decúbito ventral. A via de acesso
foi realizada através de incisão da pele em região cervical posterior
mediana, de 12 cm, seguida de dissecção dos planos musculares
junto às estruturas ósseas, com a exposição da coluna vertebral
de T1 a C2.
A sétima (C7) e sexta (C6) vértebras cervicais foram identificadas
por contagem a partir da primeira vértebra torácica (T1), identifi-
cada pela localização do primeiro arco costal. Com o objetivo de
evitar falha na identificação de C7 e C6 a partir de T1, decorrente
da possível existência de costela cervical, a contagem também foi
feita a partir da segunda vértebra cervical (Figura 1).
Realizada a remoção dos elementos posteriores de C7 (processo
espinhoso e lâminas), foram identificadas as massas laterais e fora-
mes C7-T1 bilateralmente. Por dissecção paravertebral localizou-se
a raiz nervosa C8 de ambos os lados que são seccionadas para
permitir a visualização da artéria vertebral. As massas laterais de
C7 são então cuidadosamente abertas até o forame transverso,
onde era averiguada a passagem ou não da artéria vertebral. Caso
a artéria não fosse vista passando pelo forame transverso de C7 o
mesmo procedimento é realizado em C6 para constatar a entrada
desta neste nível (Figura 2).
RESULTADOS
Como resultado deste estudo anatômico, nossa casuística foi de
16 corpos do sexo masculino (80%) e 4 do sexo feminino (20%),
18 da raça branca (90%) e 2 da raça negra (10%), altura variando
de 165 a 185cm para os homens (média de 173,75 cm) e todas
as mulheres com 170cm. A média de idade foi de 57,5 anos (32
Figura 1- Identificação das vértebras através da primeira costela torácica
Figura 2 - Entrada da artéria vertebral no forame transverso de C6
86 ACTA ORTOP BRAS 15(2: 84-86, 2007)
– 83) e de peso foi de 61,15Kg (36 – 96).
De todas as 40 artérias vertebrais dissecadas, encontramos
37 delas entrando no forame transverso da sexta vértebra
cervical C6 (92,5%), e 3 delas através do forame transverso
de C7 (7,5%).
Nenhum parâmetro antropométrico mostrou-se estatisticamen-
te significante como preditor dessa variação anatômica.
Não foram encontradas variações anatômicas consistindo
da entrada da artéria vertebral em outras vértebras cervicais.
A anormalidade foi unilateral em 1 cadáver (5%), no qual a
artéria penetrava no forame esquerdo de C7 e no forame
direito de C6, e bilateral em outro (5%), penetrando ambos
os processos transversos de C7 (Tabela 1).
DISCUSSÃO
Na literatura internacional é constatada a incidência de pas-
sagem da artéria vertebral intraforaminal transverso de C7 de
aproximadamente 6 a 7 % da população estudada(9,12). Em
recente trabalho realizado na França(15), foram estudados os
trajetos de 500 artérias vertebrais, através de 200 ressonâncias
magnéticas e 50 tomografias computadorizadas com contraste
angiográfico. Com esta grande casuística, os autores encontra-
ram variação anatômica em 7 % dos casos estudados, seme-
lhante ao observado no presente trabalho anatômico. Entre os
trajetos não habituais, a entrada da artéria vertebral no forame
ocorreu em C3, C4, C5 ou C7, com incidências, respectivamente,
de 0,2%, 1%, 5% e 0,8%. Nota-se, portanto, a entrada em C5
como variação anatômica mais freqüente do que a entrada em
C7, fato que não foi confirmado pelo nosso estudo. Outro dado
interessante também observado neste estudo francês foi a maior
incidência de anormalidade unilateral (12,4%) em comparação com
a bilateral (0,8%), sendo a maioria do lado esquerdo. Este estudo,
porém, assim como outros, não consegue correlacionar a alteração
anatômica com algum dado que permitisse ao cirurgião atuar com
mais cautela.
Há, na literatura, correlação entre entrada da artéria em forame de
nível não habitual e uma variação em sua origem da subclávia, o que
também não tem valor clínico(16).
A incidência de pessoas com trajeto não habitual da artéria vertebral
em sua passagem pela coluna cervical baixa não é desprezível,
e deve ser levada em conta quando optar-se por uma técnica de
fixação transpedicular nesta região. A violação da parede lateral
do pedículo nestas pessoas, acidente possível na introdução do
parafuso pedicular, coloca em risco a artéria vertebral, também em
C7. Tal lesão pode gerar conseqüências catastróficas, sobretudo
naqueles pacientes que apresentam débito sanguíneo inadequado
pela artéria contralateral.
O presente trabalho conta com casuística somente de 20 cadáveres.
Apesar disto, confirma de uma maneira consistente a informação
que existe hoje na literatura, através de estudo anatômico e por
imagem.
CONCLUSÕES
A artéria vertebral em seu trajeto ascendente, a partir da região
superior do tórax, penetra os forames transversos das vértebras
cervicais inicialmente em C6 (não passando por dentro do forame
de C7) 92,5% das vezes. Em 7,5% das vezes a artéria passa dentro
do forame de C7. Encontramos anormalidade unilateral em 5% dos
cadáveres, no qual a artéria penetrava no forame esquerdo de C7
e no forame direito de C6, e bilateral em outros 5%, penetrando
ambos os processos transversos de C7. Nenhum parâmetro antro-
pométrico mostrou-se estatisticamente significante como preditor
dessa variação anatômica.
REFERÊNCIAS BIBLIOGRÁFICAS
1. Kast E, Mohr K, Richter HP, Borm W. Complications of transpedicular screw
fixation in the cervical spine. Eur SpineJ. 2006; 15:327-34.
2. Abumi K, Itoh H, Taneichi H, Kaneda K. Transpedicular screw fixation for trauma-
tic lesions of middle and lower cervical spine. J Spinal Disord. 1994; 7:19-28.
3. Abumi K, Kaneda K. Pedicular screw fixation for nontraumatic lesions of the cre-
vical spine. Spine. 1997; 22:1853-63.
4. Albert TJ, Klein GR, Joffe D. Use of cervical pedicle screws for complex cervico-
thoracic spine pathology. Spine. 1998; 23:1596-9.
5. Ludwig SC, Kramer DL, Balderston RA, Vaccaro AR, Foley KF, Albert TJ. Pla-
cement of pedicle screws in the human cadaveric cervical spine: comparative
accuracy of three techniques. Spine. 2000; 25:1655-67.
6. Panjabi MM, Duranceau J, Goel V, Oxland T, Takata K . Cervical human verte-
brae. Quantitative three-dimensional anatomy of the middle and lower regions.
Spine. 1991; 16:861-9.
7. Kotani Y, Cunningham BW, Abumi K, McAfee PC. Biomechanical analysis of
cervical stabilization systems. An assessment of transpedicular screw fixation in
the cervical spine. Spine. 1994; 19:2529-39.
8. Barrey C, Mertens P, Jund J, Cotton F, Perrin G. Quantitative anatomic evaluation
of cervical lateral mass fixation with a comparison of the Roy-Camille and the
Magerl screw techniques. Spine. 2005; 30:E140-7.
9. Heary RF, Albert TJ, Ludwig SC, Vaccaro AR, Wolansky LJ, Leddy TP, et al.
Surgical anatomy of the vertebral arteries. Spine. 1996; 21:2074-80.
10. Xu R, Ebraheim NA, Yeasting R, Wong F, Jackson W T. Anatomy of C7 lateral
mass and projection of pedicle axis on its posterior aspect. J Spinal Disord.
1995; 8:116-20.
11. Abumi K, Shono Y, Ito M, Taneichi H, Kotani Y, Kaneda K. Complications of pe-
dicle screw fixation in reconstructive surgery of the cervical spine. Spine 2000;
25:962-9.
12. Ebraheim NA, Reader D, Xu R, Yeasting RA. Location of the vertebral artery fora-
men on the anterior aspect of the lower cervical spine by computed tomography.
J Spinal Disord. 1997; 10:304-7.
13. Ebraheim NA, Xu R, Yeasting RA. The location of the vertebral artery foramen
and its relation to posterior lateral mass screw fixation. Spine. 1996; 21:1291-
95.
14. Ebraheim NA, Lu J, Brown JA, Biyani A, Yeasting RA. Vulnerability of vertebral
artery in anterolateral decompression for cervical spondylosis. Clinical Orthop
Relat Res 1996; (322):146-51.
15. Bruneau M, Cornelius JF, Marneffe V, Triffaux M, George B. Anatomical variations
of the V2 segment of the vertebral artery. Neurosurgery. 2006; 59(1 Suppl 1):
ONS20-4.
16. Yamaki K, Saga T, Hirata T, Sakaino M, Nohno M, Kobayashi S, et al. Anatomical
study of the ver tebral artery in Japanese adults. Anat Sci Int. 2006; 81:100-6.
TABELA 1 - Características dos cadáveres
Raça Sexo Idade Altura Peso Nível de entrada da
(anos) (cm) (Kg) a. vertebral
1 Br M 34 185 62 C7
2 Br M 51 170 60 C6
3 Br M 65 180 96 C6
4 Br M 83 165 60 C6
5 Br F 39 170 60 C6
6 Br M 62 180 68 C6
7 Br F 41 170 60 C6
8 Br F 80 170 36 C6
9 Br F 61 170 60 C6
10 Ng M 56 170 60 C6
11 Ng M 50 170 43 C6
12 Br M 32 180 65 C6
13 Br M 60 180 40 C6
14 Br M 47 170 60 C6
15 Br M 78 170 80 C6
16 Br M 66 180 80 C6
17 Br M 72 170 56 C6 D/ C7 E
18 Br M 71 170 57 C6
19 Br M 60 170 60 C6
20 Br M 42 170 60 C6
Br= branco, Ng= negro, M=masculino, F=feminino, a.=artéria, trans.=transversal,
col.=coluna
... Portanto, a artéria vertebral, ramo da artéria subclávia, penetra no forame transverso da sexta vértebra cervical, ascendendo até o forame da vértebra atlas, onde insere no crânio, através do forame magno. Por fim, as artérias vertebrais direita e esquerda se unem, formando a artéria basilar que, por sua vez, contribui para a formação do Polígono de Willis (MOORE et al., 2019;AKAR et al., 2015;KAJIMOTO et al., 2007;ZIBIS et al., 2017). ...
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The biomechanical stability of seven cervical reconstruction methods including the transpedicular screw fixation was evaluated under four instability patterns. These four modalities, based on the range and grade of instability, allowed a reproducible biomechanical assessment to establish the in vitro role of internal fixation in the cervical spine. This study biomechanically investigated the stability of seven reconstruction methods in the cervical spine as influenced by four instability patterns and assessed whether three-column fixation for the cervical spine using transpedicular screw fixation would provide increased stability over that of conventional cervical fixation systems. A total of 24 calf cervical spine specimens were divided into four experimental groups. The spinal constructs including seven reconstruction techniques--the posterior AO titanium reconstruction plate, Bohlman's posterior triple-wiring, transpedicular screw fixation, anterior iliac bone graft, anterior AcroMed plate, anterior AO titanium locking plate, and combined fixation with the AO anterior plate and posterior triple-wiring--were tested under four loading modes. Anterior plating methods provided less stability than that of posterior constructs under axial, torsional, and flexural loading conditions. Exclusive posterior procedures provided increased stability compared with the intact spine in one level fixation, however, did not sustain the torsional stability when the anterior and middle column was eliminated in two-level fixation. The stabilizing capabilities of both the combined fixation and transpedicular screw fixation were clearly demonstrated in all loading modes, however, those of the latter were superior in multilevel fixation. Front and back approaches, employing the anterior plate and posterior triple-wiring, and transpedicular screw fixation demonstrated clear biomechanical advantages when the extent of instability increased to three-column or multilevel. Three-column fixation for the cervical spine using transpedicular screw fixation offers increased stability over that of conventional cervical fixation systems, particularly in multiple level constructs.
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Thirteen patients with fractures and/or dislocations of the middle and lower cervical spine were treated by transpedicular screw fixation using the Steffee variable screw placement system. Postoperative immobilization was either not used or simplified to short-term use of a soft neck collar. Recovery of nerve function and correction of kyphotic and/or translational deformities were satisfactory. All patients had solid fusion without loss of correction at the latest follow-up. There were no neurovascular complications. It was concluded that transpedicular screw fixation is as strong a fixation procedure for the cervical spine as it is for the thoracic and lumbar spine. This surgical procedure is associated with some risks of major neurovascular injuries; however, safety is adequate if the procedure is performed by experienced surgeons using meticulous surgical techniques.
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This retrospective study was conducted to analyze the clinical results in 45 patients with nontraumatic lesions of the cervical spine treated by pedicle screw fixation. To evaluate the effectiveness of pedicle screw fixation in reconstructive surgery for nontraumatic cervical spinal disorders. Pedicle screw fixation for hangman's fracture of the axis and traumatic lesions of the middle and lower cervical spine has been reported; however, there have been no reports on pedicle screw fixation for nontraumatic lesions of the cervical spine. Forty-five patients with nontraumatic lesions of the cervical spine underwent reconstructive surgery including pedicle screw fixation and fusion. Five patients underwent occipitocervical fixation for the lesion of the upper cervical spine, and one patient underwent separate occipitocervical fixation and cervicothoracic fixation. Cervical or cervicothoracic fixation was performed in 39 patients. Twenty-six of these patients underwent simultaneous laminectomy or laminoplasty. Supplemental anterior surgery was conducted for 15 patients. Solid fusion was obtained in all patients except eight with metastatic vertebral tumors who did not receive bone graft. Correction of kyphosis was adequate. There were no neurovascular complications, except one case of transient radiculopathy caused by screw threads. Pedicle screw fixation is a useful procedure for posterior reconstruction of the cervical spine. This procedure does not require the lamina for stabilization, and should be especially valuable for simultaneous posterior decompression and fusion. The risk to neurovascular structures, however, cannot be completely eliminated.
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In this study, the three-dimensional quantitative anatomy of middle and lower cervical vertebrae was determined. The three-dimensional coordinates of various marked points on the surface of the vertebra were measured with a specially designed morphometer instrument. From these coordinates, linear dimensions, angulations, and areas of surfaces and cross-sections of most vertebral components were calculated. The results showed two distinct transition regions: 1) toward the thoracic spine by the wider C7 vertebra but narrower spinal canal; and 2) toward the upper cervical region with the larger pedicle and spinous process of C2. Based on the study of 72 human cervical vertebrae, mean and standard error of the mean values of some clinically important dimensions of vertebral body, spinal canal, pedicles, transverse processes, spinous process, and uncovertebral joints are given for C2-C7 vertebrae. The areas of the end plates, spinal canal, and pedicles were modeled by elliptical and triangular shapes, and results were compared with the actual measurements.
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A specimen study focused on the measurements of C7 lateral mass and pedicle as well as the projection of pedicle axis on the posterior aspect of the lateral mass was done, based on 56 whole clean, dry, well-preserved spines of skeletally mature adults, 32 males and 24 females. Lateral mass widths averaged 11.7 mm. Lateral mass heights averaged 14.8 mm. The average thickness of the lateral mass was 6.8 mm. The average pedicle widths were 6.2 mm, and the average heights were 7.0 mm. Small, but statistically significant differences were found between the averages of the aforementioned dimensions in the male and female groups. The angulation between pedicle axis and the posterior aspect of the lateral mass averaged 107.0 degrees in the transverse plane and 76.2 degrees in the sagittal plane, respectively. Differences in angulations were not significant when compared according to side or sex of group. Distances from the projection point of pedicle axis to a line passing through the mid-line of the transverse process ranged from 2 mm superior to the line to 4.5 mm inferior, with an average 1.2 mm inferior on right side and 0.3 mm inferior on the left. Distances from the pedicular axial projection point to the outer margin of the lateral mass ranged from 0.0 mm to 5.4 mm, with an average 2.4 mm on the right side and 2.9 mm on the left side. Differences of distance related to left or right side were statistically significant, whereas the distances when related to the sex of the group were not.(ABSTRACT TRUNCATED AT 250 WORDS)
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This study aimed to provide anatomic data for the location of the vertebral artery and offer an optimal approach for lateral cervical decompression that minimizes the risk of injury to the vertebral artery. Anatomically, there has been little study documenting the safe zone to prevent vertebral artery injury during the resection of the uncinate process or uncovertebral joint during the lateral decompression of the nerve root. The transverse foramen and its related parameters were measured on dry cervical spines from C3 to C7. The cadaveric cervical spines were dissected to determine a method for resection of the uncovertebral joint with decreased risk of vertebral artery laceration. The anteroposterior diameters of the transverse foramina gradually decreased from C6 to C3. The transverse diameters of the transverse foramina were smaller at C5. The interforaminal distance, width of the vertebrae, interuncinate distance, and the distance from the lateral tip of the uncinate process to the medial border of the transverse foramen became smaller in more cephalad vertebrae. After subtotal vertebrectomy and opening of the anterior walls of the transverse foramina, the resection of the uncovertebral joint and lateral decompression became easier and safer. Anatomic measurements obtained in this study indicate the vertebral artery to be at risk during decompression of the more cephalad vertebrae. The lateral decompression can be completed under direct vision with smaller rongeurs and curettes, rather than with high speed burr after deroofing the anterior walls of transverse foramina and retracting the vertebral artery laterally.
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This study evaluated the anatomic relationship between the vertebral artery foramen and the posterior midpoint of the cervical lateral mass using cervical spine specimens. To determine quantitatively the location of the vertebral artery foramens from C3 to C6 and their relationship to the posterior midpoints of the lateral masses. Anatomic studies of the cervical nerve root and facet relative to lateral mass screw placement have been addressed. It is necessary to know the correct location of the vertebral artery foramen during lateral mass screw placement to minimize the risk of injury to the vertebral artery. Forty-three cervical spines from C3 to C6 were directly evaluated for this study. Anatomic evaluation included the dimension of the vertebral artery foramen and its projection on the posterior aspect of the lateral mass. The vertical distance from the posterior midpoint of the lateral mass to the posterior border of the vertebral artery foramen, and the angle between the parasagittal plane and the line connecting the posterior midpoint of the lateral mass with the lateral limit of the vertebral artery foramen, were also measured. The vertical distances from the posterior midpoint of the lateral mass to the vertebral artery foramens at C3-C6 averaged from 9.3 to 12.2 mm for male and female specimens. The average angles medial to the sagittal plane, between the parasagittal plane and the line connecting the posterior midpoint of the lateral mass with the lateral limit of the vertebral artery foramen, from C3 to C5, were found to range from 6.0 degrees to 6.3 degrees for male specimens and from 5.3 degrees to 5.5 degrees for female specimens. At C6, the average angles lateral to the sagittal plane, between the parasagittal plane and the line connecting the posterior midpoint of the lateral mass with the lateral limit of the vertebral artery foramen, were 6.4 degrees for male specimens and 5.4 degrees for female specimens. The present study indicated that there is no risk of damaging the vertebral artery if a screw is directed perpendicular to the posterior aspect of the lateral mass at C3-C5 and 10 degrees lateral to the sagittal plane at C6 starting at the midpoint of the lateral mass.
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This study compared direct measurements of the distances between the vertebral arteries in the cervical spines of human cadaver specimens with data obtained from axial computed tomography images of these specimens. To determine whether the information obtained from a computed tomography scan can be used reliably to predict the true anatomic location of the vertebral arteries and, in so doing, provide accurate guidelines for the lateral extent of anterior cervical decompressive procedures. Iatrogenic vertebral artery injury during anterior cervical surgery is uncommon, potentially catastrophic, and avoidable. The means and standard deviation of measurements of the location of the cervical segment of the vertebral arteries obtained with high-precision, digital calipers by direct gross anatomic dissection of 16 adult (eight male, eight female) cadaver specimens were recorded. These measurements were compared with computed tomography scan data obtained on the same specimens. The mean distances between the vertebral arteries progressively increased from C3 to C6. Computed tomography scan measurements of the distance between the cervical foramina transversaria were consistently smaller than direct measurements of the gross specimens. At C6, the computed tomography scan data were significantly less than the gross anatomic data. According to these data, computed tomography scan measurements may be used safely and accurately to plan the lateral extent of anterior cervical decompressive surgical procedures. Although the data obtained from the gross anatomic dissections may serve as guidelines to assist the surgeon, the authors recommend a careful review of the preoperative computed tomography scan on an individual case-by-case basis as the safest method to plan for anterior cervical surgery.
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Axial computed tomography scans were performed on 14 cadaveric cervical spines to determine the location of the vertebral artery foramen on the anterior aspect of the lower cervical spine. The best scan through the vertebral artery foramen from each level at C3-C6 was selected. Measurements of the vertebral artery foramen included the foramen depth, foramen width, interforaminal distance, the distance from the anterior border of the transverse foramen to the anterior border of the transverse process, the distance from the posterior border of the transverse foramen to the posterior border of the lateral mass, and the distance from the medial border of the vertebral artery foramen to the lateral border of the vertebral body. The results show that the average transverse foramen width was 5.5 +/- 0.4 mm at C3, 5.7 +/- 1.0 mm at C4, 5.9 +/- 0.7 mm at C5, and 5.7 +/- 0.7 mm at C6. The average transverse foramen depth and average interforaminal distance gradually increased from C3 to C6. The distance from the anterior border of the vertebral artery foramen to the anterior border of the transverse process gradually increased from C3 (1.2 +/- 0.4 mm) to C6 (2.7 +/- 0.8 mm) as well. The average distance between the medial border of the transverse foramina and the lateral border of the vertebral body for C3-C6 ranged from 1.8 to 2.2 mm. The average distance between the anterior borders of the vertebral artery foramina and the anterior border of the vertebral body gradually decreased from C3 (8.4 +/- 1.4 mm) to C6 (7.0 +/- 1.6 mm). This study suggested that the lateral border of the vertebral body may be a reliable landmark during anterior cervical decompression. The vertebral artery foramen should be free of violation if vertebrectomy or subtotal vertebrectomy is performed medial to the lateral border of the vertebral body.
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A retrospective review of 21 patients in which cervical pedicle screw fixation was used at C7 with or without upper thoracic pedicle screw fixation. To evaluate the use of pedicle screw placement in the lower cervical spine. The use of posterior cervical spine fixation, including lateral mass fixation, has become increasingly popular in recent years. However, lateral mass fixation at C7 is often hindered by lack of substantial high quality bone. The end level of long cervical spine constructs is frequently C7 or T1. Dissatisfaction with lateral mass fixation at C7 and T1 led the authors to use lower cervical pedicle screw fixation for several cervical spine disorders. Twenty-one patients who had undergone cervical pedicle screw fixation at C7 were reviewed retrospectively. There were 12 males and 9 females, with an average age of 52 years. All pedicle screws were placed, after direct palpation of the pedicle, with a right angle nerve hook after laminoforaminotomy at C7. There were no neurologic complications related to pedicle screw placement, and no patient was symptomatically worse after the operation. Six patients with root pathology improved. Of 14 patients with cervical myelopathy, 12 improved at least one Nurick grade, and 2 had no improvement. There were no failures of fixation or complications related to pedicle fixation at a minimum of 1 year follow-up. Pedicle screws in C7 placed with laminoforaminotomy and palpation technique appears to be safe and efficacious. Excellent fixation can be achieved.