Periodontoid Pseudotumor with Respiratory Arrest.

Sir, Periodontoid pseudotumor typically presents in elderly patients with a long-standing history of myelopathies, such as gait disturbance, fine motor skills disturbance, and numbness.[1,2] We present the first case of periodontoid pseudotumor with respiratory arrest. The patient was an 83-year-old man who experienced a sudden collapse. His daughter heard the sound of the collapse and found him lying at the front door. When the emergency medical technicians checked him, he was in a state of respiratory arrest, so he was transported to our hospital with instrumental airway and bag-valve ventilation. His relevant medical history included only hypertension and lumbar spinal stenosis at L4/5, and he was independent in his activities of daily living. On arrival, his vital signs were as follows: Glasgow Coma Scale, E1V1M1; blood pressure, 165/86 mmHg; heart rate, 77 beats per min; respiration rate, 0 breaths per min; body temperature, 36.1°C; percutaneous saturation of oxygen under bag-valve ventilation with oxygen, 99%. The main results of a biochemical blood analysis on arrival were mild inflammation (C-reactive protein, 0.82 mg/dL), anemia (hemoglobin, 8.4 g/dL), and elevated lactate dehydrogenase (283 U/L). Head computed tomography (CT) showed no intracranial hemorrhagic lesions; however, heterogeneous density was observed in the retro-odontoid process area [Figure 1]. Head magnetic resonance imaging (MRI) showed a calcified mass at the retro-odontoid process compressing the cervicomedullary junction, which was accompanied by ischemic change and hematoma in front of the upper cervical spine [Figure 1]. He was diagnosed with traumatic cervicomedullary injury due to compression by an antecedent periodontoid pseudotumor and traumatic insult. The patient had a poor prognosis and was therefore treated conservatively. He died on day 7. His family did not give him permission to perform an autopsy.Figure 1: CT and MRI on arrival. CT showed no intracranial hemorrhagic lesions; however, mild heterogeneous density was observed in the retro-odontoid process area (black triangle). On T1- and T2-weighted MRI of the head, a low-intensity mass was observed in the retro-odontoid process, suggesting calcification, and compression of the cervicomedullary junction (white triangle), which was accompanied by ischemic change (asterisk). On T1- and T2-weighted MRI, a high-intensity area was observed in front of the upper cervical spine, suggesting hematoma (white arrow). CT: Computed tomography, MRI: Magnetic resonance imagingTo the best of our knowledge, this is the first reported case in which periodontoid pseudotumor was found after the collapse with respiratory arrest. Respiratory arrest can be caused by airway obstruction, decreased respiratory effort, and/or respiratory muscle weakness.[3] The decreased respiratory effort reflects central nervous system (CNS) impairment due to one of the following conditions: CNS disorder, a drug-related adverse effect, or metabolic disorder. CNS disorders that affect the brainstem (stroke, infection, tumor, and/or trauma) can cause hypoventilation.[3] The present case involved antecedent cervicomedullary junction compression by a periodontoid pseudotumor in addition to trauma insult, which resulted in respiratory arrest. The present case was therefore considered to have decreased respiratory effort due to CNS disorder. In emergency cases of collapse with respiratory arrest, it is important to identify mass lesions, including periodontoid pseudotumors. Both CT and MRI were helpful in identifying the periodontoid pseudotumor. This unique case adds one more cause to the list of documented etiologies of sudden collapse with respiratory arrest. Declaration of patient consent The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient’s family has given his consent for his image and other clinical information to be reported in the journal. The patient’s family understands that his name and initial will not be published and due efforts will be made to conceal his identity, but anonymity cannot be guaranteed. Research quality and ethics statement The authors followed applicable EQUATOR Network (https://www.equator-network.org/) guidelines, notably the CARE guideline, during the conduct of this report. Financial support and sponsorship This work was supported in part by a Grant-in-Aid for Special Research in Subsidies for ordinary expenses of private schools from The Promotion and Mutual Aid Corporation for Private Schools of Japan. Conflicts of interest There are no conflicts of interest.