Letter to the Editor
Cervical myelopathy as the initial manifestation of os odontoideum
Mielopatía cervical como forma de presentación de un os odontoideo
H. Tejada Meza
, P. Modrego Pardo, J. Gazulla Abio
Corresponding author
Departamento de Neurología, Hospital Universitario Miguel Servet, Zaragoza, Spain
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Tejada Meza, P. Modrego Pardo, J. Gazulla Abio" "autores" => array:3 [ 0 => array:4 [ "nombre" => "H." "apellidos" => "Tejada Meza" "email" => array:1 [ 0 => "htmeza@gmail.com" ] "referencia" => array:1 [ 0 => array:2 [ "etiqueta" => "<span class="elsevierStyleSup">*</span>" "identificador" => "cor0005" ] ] ] 1 => array:2 [ "nombre" => "P." "apellidos" => "Modrego Pardo" ] 2 => array:2 [ "nombre" => "J." "apellidos" => "Gazulla Abio" ] ] "afiliaciones" => array:1 [ 0 => array:2 [ "entidad" => "Departamento de Neurología, Hospital Universitario Miguel Servet, Zaragoza, Spain" "identificador" => "aff0005" ] ] "correspondencia" => array:1 [ 0 => array:3 [ "identificador" => "cor0005" "etiqueta" => "⁎" "correspondencia" => "Corresponding author." ] ] ] ] "titulosAlternativos" => array:1 [ "es" => array:1 [ "titulo" => "Mielopatía cervical como forma de presentación de un <span class="elsevierStyleItalic">os</span> odontoideo" ] ] "resumenGrafico" => array:2 [ "original" => 0 "multimedia" => array:7 [ "identificador" => "fig0005" "etiqueta" => "Figure 1" "tipo" => "MULTIMEDIAFIGURA" "mostrarFloat" => true "mostrarDisplay" => false "figura" => array:1 [ 0 => array:4 [ "imagen" => "gr1.jpeg" "Alto" => 844 "Ancho" => 900 "Tamanyo" => 109352 ] ] "descripcion" => array:1 [ "en" => "<p id="spar0005" class="elsevierStyleSimplePara elsevierViewall">Cervical MR image showing compression of the spinal cord at the cervicomedullary junction.</p>" ] ] ] "textoCompleto" => "<span class="elsevierStyleSections"><p id="par0005" class="elsevierStylePara elsevierViewall">Os odontoideum is a bone malformation in which there is a separation between the odontoid process and the body of the axis (C2). It may cause atlantoaxial dislocation, presenting with severe clinical symptoms, including cervical pain, torticollis, headache, neurological symptoms secondary to spinal cord or vertebral artery compression, and even sudden death.</p><p id="par0010" class="elsevierStylePara elsevierViewall">Further research is necessary to accurately determine the aetiology and treatment of this disorder. Likewise, population studies should be conducted to estimate its prevalence.</p><p id="par0015" class="elsevierStylePara elsevierViewall">We present the case of a patient with cervical compressive myelopathy secondary to atlantoaxial dislocation in the context of os odontoideum.</p><span id="sec0005" class="elsevierStyleSection elsevierViewall"><span class="elsevierStyleSectionTitle" id="sect0005">Clinical case</span><p id="par0020" class="elsevierStylePara elsevierViewall">Our patient was a 25-year-old woman with no relevant medical history, including no history of head or neck trauma, and a low-risk job. She had a 3-year history of progressive difficulty walking due to subjective left-sided weakness but showed no dysphagia or other symptoms. The physical examination revealed deep tendon reflexes, ankle clonus, and Babinski sign present on the left side of her body. We found no skin hyperlaxity, joint hypermobility, or alterations in temperature and pain sensitivity.</p><p id="par0025" class="elsevierStylePara elsevierViewall">The complementary tests found no signs of either rheumatic disease or disorders of calcium and phosphate metabolism. A neck MRI scan displayed previous atlantoaxial dislocation, which compressed the spinal cord at the cervicomedullary junction (<a class="elsevierStyleCrossRef" href="#fig0005">Fig. 1</a>). A complementary CT scan of the cervical spine revealed os odontoideum (<a class="elsevierStyleCrossRef" href="#fig0010">Fig. 2</a>). The figures show the os odontoideum protruding above the Chamberlain line, an imaginary line joining the back of the hard palate with the opisthion on a lateral view of the cervical spine. As no other bone lesions can be seen, this finding indicates basilar invagination.</p><elsevierMultimedia ident="fig0005"></elsevierMultimedia><elsevierMultimedia ident="fig0010"></elsevierMultimedia><p id="par0030" class="elsevierStylePara elsevierViewall">The patient underwent occipitocervical arthrodesis and a bilateral C1 laminectomy; as a result of the intervention, left-sided weakness subsided.</p></span><span id="sec0010" class="elsevierStyleSection elsevierViewall"><span class="elsevierStyleSectionTitle" id="sect0010">Discussion</span><p id="par0035" class="elsevierStylePara elsevierViewall">There are 2 widely accepted hypotheses about the aetiology of os odontoideum. The first suggests that the anomaly is secondary to an odontoid synchondrosis fracture before the synchondrosis fuses (by the age of 5 or 6)<a class="elsevierStyleCrossRef" href="#bib0070"><span class="elsevierStyleSup">1</span></a>; during growth, the alar ligaments progressively pull the odontoid process fragment, which detaches from the base of the axis but keeps receiving nutrients via the blood supply from the apical arcade (in some series, trauma was the aetiology in up to 56% of the patients).<a class="elsevierStyleCrossRef" href="#bib0075"><span class="elsevierStyleSup">2</span></a> The second hypothesis proposes that os odontoideum has a congenital origin, as may be the case in our patient, since the CT scan of the cervical spine revealed the presence of basilar invagination. The presence of os odontoideum has been described in identical twins<a class="elsevierStyleCrossRef" href="#bib0080"><span class="elsevierStyleSup">3</span></a> as well as in families, suggesting an autosomal dominant pattern.<a class="elsevierStyleCrossRefs" href="#bib0085"><span class="elsevierStyleSup">4,5</span></a> Some researchers have found genes associated with the disease, a few of which are linked to morphogenesis and bone maintenance. Between twins with os odontoideum and a control group, Straus et al.<a class="elsevierStyleCrossRef" href="#bib0095"><span class="elsevierStyleSup">6</span></a> identified differences in the expression of 213 genes, and also found increased expression of the genes <span class="elsevierStyleItalic">MMP8</span>, <span class="elsevierStyleItalic">KIT</span>, <span class="elsevierStyleItalic">HIF1A</span>, <span class="elsevierStyleItalic">CREB3</span>, <span class="elsevierStyleItalic">PWHAZ</span>, <span class="elsevierStyleItalic">TGFBR1</span>, <span class="elsevierStyleItalic">NFKB2</span>, <span class="elsevierStyleItalic">FGFR1</span>, <span class="elsevierStyleItalic">IPO8</span>, <span class="elsevierStyleItalic">STAT1</span>, COL1<span class="elsevierStyleItalic">A1</span>, and <span class="elsevierStyleItalic">BMP3</span> in a group of patients with os odontoideum.</p><p id="par0040" class="elsevierStylePara elsevierViewall">Depending on the position of the odontoid process fragment, os odontoideum may be classified as orthotopic, when the fragment is in its anatomical position, or dystopic, when it is displaced (as in our case). Dystopic os odontoideum usually presents with a narrowing of the craniocervical junction and is the type most frequently associated with atlantoaxial dislocation.</p><p id="par0045" class="elsevierStylePara elsevierViewall">Clinical expression of os odontoideum is variable and may be divided into 4 categories: 1) asymptomatic (even in cases of atlantoaxial dislocation demonstrated by imaging techniques), 2) local symptoms (cervical pain, torticollis, headache), 3) other symptoms associated with cervical compressive myelopathy (which may be transient, static, or progressive),<a class="elsevierStyleCrossRef" href="#bib0100"><span class="elsevierStyleSup">7</span></a> and 4) symptoms secondary to vertebrobasilar ischaemia.<a class="elsevierStyleCrossRefs" href="#bib0105"><span class="elsevierStyleSup">8,9</span></a> Cases of sudden death have also been reported.</p><p id="par0050" class="elsevierStylePara elsevierViewall">Diagnosis is based on imaging findings and cervical radiographs usually suffice.<a class="elsevierStyleCrossRef" href="#bib0110"><span class="elsevierStyleSup">9</span></a> However, CT and MR images are more precise and also show spinal cord involvement. In the case presented here, and despite their diagnostic capacity, no cervical flexion-extension images were taken as performing them could have been perjudicial to our patient's clinical state.</p><p id="par0055" class="elsevierStylePara elsevierViewall">Currently recommended treatments for os odontoideum are supported by class III medical evidence only.<a class="elsevierStyleCrossRef" href="#bib0110"><span class="elsevierStyleSup">9</span></a> Asymptomatic patients with no atlantoaxial dislocation may be treated conservatively with clinical and radiological follow-up: although most series describe no progression, some patients may present atlantoaxial dislocation at later stages.<a class="elsevierStyleCrossRefs" href="#bib0115"><span class="elsevierStyleSup">10,11</span></a> Surgery, especially posterior C1-C2 fixation and arthrodesis, is recommended for patients with neurological symptoms and atlantoaxial dislocation.<a class="elsevierStyleCrossRefs" href="#bib0110"><span class="elsevierStyleSup">9,12</span></a> Surgery is also recommended for asymptomatic patients with atlantoaxial dislocation since minor cervical trauma may result in spinal cord damage,<a class="elsevierStyleCrossRefs" href="#bib0075"><span class="elsevierStyleSup">2,9,10</span></a> although in some studies, patients who did not undergo surgery displayed no symptoms during follow-up.<a class="elsevierStyleCrossRefs" href="#bib0070"><span class="elsevierStyleSup">1,13</span></a></p><p id="par0060" class="elsevierStylePara elsevierViewall">In our case, congenital os odontoideum, as indicated by the presence of basilar invagination, manifested as left-sided weakness and pyramidal signs which were secondary to spinal cord compression following anterior atlantoaxial dislocation.</p></span><span id="sec0015" class="elsevierStyleSection elsevierViewall"><span class="elsevierStyleSectionTitle" id="sect0015">Conflicts of interest</span><p id="par0065" class="elsevierStylePara elsevierViewall">The authors have no conflicts of interest to declare.</p></span></span>" "textoCompletoSecciones" => array:1 [ "secciones" => array:4 [ 0 => array:2 [ "identificador" => "sec0005" "titulo" => "Clinical case" ] 1 => array:2 [ "identificador" => "sec0010" "titulo" => "Discussion" ] 2 => array:2 [ "identificador" => "sec0015" "titulo" => "Conflicts of interest" ] 3 => array:1 [ "titulo" => "References" ] ] ] "pdfFichero" => "main.pdf" "tienePdf" => true "NotaPie" => array:1 [ 0 => array:2 [ "etiqueta" => "☆" "nota" => "<p class="elsevierStyleNotepara" id="npar0005">Please cite this article as: Tejada Meza H, Modrego Pardo P, Gazulla Abio J. Mielopatía cervical como forma de presentación de un <span class="elsevierStyleItalic">os</span> odontoideo. Neurología. 2016;31:278–279.</p>" ] ] "multimedia" => array:2 [ 0 => array:7 [ "identificador" => "fig0005" "etiqueta" => "Figure 1" "tipo" => "MULTIMEDIAFIGURA" "mostrarFloat" => true "mostrarDisplay" => false "figura" => array:1 [ 0 => array:4 [ "imagen" => "gr1.jpeg" "Alto" => 844 "Ancho" => 900 "Tamanyo" => 109352 ] ] "descripcion" => array:1 [ "en" => "<p id="spar0005" class="elsevierStyleSimplePara elsevierViewall">Cervical MR image showing compression of the spinal cord at the cervicomedullary junction.</p>" ] ] 1 => array:7 [ "identificador" => "fig0010" "etiqueta" => "Figure 2" "tipo" => "MULTIMEDIAFIGURA" "mostrarFloat" => true "mostrarDisplay" => false "figura" => array:1 [ 0 => array:4 [ "imagen" => "gr2.jpeg" "Alto" => 455 "Ancho" => 1901 "Tamanyo" => 90168 ] ] "descripcion" => array:1 [ "en" => "<p id="spar0010" class="elsevierStyleSimplePara elsevierViewall">Cervical CT image revealing the presence of os odontoideum and anterior atlantoaxial dislocation. The upper part of the os odontoideum protrudes above the Chamberlain line (line joining the back of the hard palate with the opisthion), indicating basilar invagination.</p>" ] ] ] "bibliografia" => array:2 [ "titulo" => "References" "seccion" => array:1 [ 0 => array:2 [ "identificador" => "bibs0005" "bibliografiaReferencia" => array:13 [ 0 => array:3 [ "identificador" => "bib0070" "etiqueta" => "1" "referencia" => array:1 [ 0 => array:2 [ "contribucion" => array:1 [ 0 => array:2 [ "titulo" => "<span class="elsevierStyleItalic">Os odontoideum</span>" "autores" => array:1 [ 0 => array:2 [ "etal" => false "autores" => array:3 [ 0 => "J.W. Fielding" 1 => "R.N. Hensinger" 2 => "R.J. 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| Year/Month | Html | Total | |
|---|---|---|---|
| 2024 October | 32 | 3 | 35 |
| 2024 September | 69 | 17 | 86 |
| 2024 August | 43 | 7 | 50 |
| 2024 July | 63 | 6 | 69 |
| 2024 June | 37 | 4 | 41 |
| 2024 May | 42 | 6 | 48 |
| 2024 April | 37 | 10 | 47 |
| 2024 March | 40 | 9 | 49 |
| 2024 February | 75 | 5 | 80 |
| 2024 January | 82 | 8 | 90 |
| 2023 December | 59 | 10 | 69 |
| 2023 November | 91 | 6 | 97 |
| 2023 October | 95 | 7 | 102 |
| 2023 September | 70 | 3 | 73 |
| 2023 August | 61 | 5 | 66 |
| 2023 July | 72 | 7 | 79 |
| 2023 June | 72 | 2 | 74 |
| 2023 May | 103 | 16 | 119 |
| 2023 April | 88 | 4 | 92 |
| 2023 March | 84 | 4 | 88 |
| 2023 February | 74 | 4 | 78 |
| 2023 January | 81 | 18 | 99 |
| 2022 December | 74 | 14 | 88 |
| 2022 November | 117 | 8 | 125 |
| 2022 October | 82 | 14 | 96 |
| 2022 September | 67 | 12 | 79 |
| 2022 August | 77 | 11 | 88 |
| 2022 July | 65 | 10 | 75 |
| 2022 June | 49 | 5 | 54 |
| 2022 May | 68 | 12 | 80 |
| 2022 April | 60 | 11 | 71 |
| 2022 March | 86 | 21 | 107 |
| 2022 February | 76 | 13 | 89 |
| 2022 January | 91 | 9 | 100 |
| 2021 December | 70 | 18 | 88 |
| 2021 November | 63 | 8 | 71 |
| 2021 October | 60 | 19 | 79 |
| 2021 September | 74 | 13 | 87 |
| 2021 August | 62 | 10 | 72 |
| 2021 July | 41 | 5 | 46 |
| 2021 June | 43 | 11 | 54 |
| 2021 May | 45 | 14 | 59 |
| 2021 April | 148 | 23 | 171 |
| 2021 March | 87 | 9 | 96 |
| 2021 February | 58 | 10 | 68 |
| 2021 January | 59 | 10 | 69 |
| 2020 December | 55 | 11 | 66 |
| 2020 November | 58 | 8 | 66 |
| 2020 October | 55 | 13 | 68 |
| 2020 September | 54 | 7 | 61 |
| 2020 August | 58 | 8 | 66 |
| 2020 July | 50 | 14 | 64 |
| 2020 June | 45 | 7 | 52 |
| 2020 May | 34 | 16 | 50 |
| 2020 April | 27 | 3 | 30 |
| 2020 March | 47 | 4 | 51 |
| 2020 February | 43 | 8 | 51 |
| 2020 January | 49 | 12 | 61 |
| 2019 December | 41 | 9 | 50 |
| 2019 November | 31 | 12 | 43 |
| 2019 October | 32 | 4 | 36 |
| 2019 September | 48 | 7 | 55 |
| 2019 August | 16 | 2 | 18 |
| 2019 July | 19 | 8 | 27 |
| 2019 June | 31 | 27 | 58 |
| 2019 May | 41 | 27 | 68 |
| 2019 April | 104 | 17 | 121 |
| 2019 March | 35 | 8 | 43 |
| 2019 February | 21 | 6 | 27 |
| 2019 January | 6 | 7 | 13 |
| 2018 December | 13 | 8 | 21 |
| 2018 November | 11 | 5 | 16 |
| 2018 October | 21 | 6 | 27 |
| 2018 September | 18 | 3 | 21 |
| 2018 August | 12 | 0 | 12 |
| 2018 July | 14 | 0 | 14 |
| 2018 June | 6 | 1 | 7 |
| 2018 May | 12 | 1 | 13 |
| 2018 April | 10 | 1 | 11 |
| 2018 March | 11 | 0 | 11 |
| 2018 February | 20 | 3 | 23 |
| 2018 January | 7 | 0 | 7 |
| 2017 December | 25 | 1 | 26 |
| 2017 November | 13 | 0 | 13 |
| 2017 October | 13 | 2 | 15 |
| 2017 September | 13 | 0 | 13 |
| 2017 August | 16 | 1 | 17 |
| 2017 July | 14 | 1 | 15 |
| 2017 June | 17 | 6 | 23 |
| 2017 May | 22 | 4 | 26 |
| 2017 April | 13 | 3 | 16 |
| 2017 March | 19 | 26 | 45 |
| 2017 February | 14 | 1 | 15 |
| 2017 January | 22 | 1 | 23 |
| 2016 December | 11 | 2 | 13 |
| 2016 November | 26 | 6 | 32 |
| 2016 October | 26 | 8 | 34 |
| 2016 September | 24 | 2 | 26 |
| 2016 August | 15 | 3 | 18 |
| 2016 July | 26 | 3 | 29 |
| 2016 June | 42 | 13 | 55 |
| 2016 May | 47 | 16 | 63 |
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