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CASE REPORT
Year : 2023 | Volume
: 14
| Issue : 1 | Page : 103-107
Our experiences in patients with atlanto-occipital dislocation: A case series with literature review
Abdoulhadi Daneshi1, Abolfazl Rahimizadeh2, Arash Fattahi1, Saina Darvishnia3, Omid Masoudi1, Seyed Mohammad Reza Mohajeri1
1 Department of Neurosurgery, School of Medicine, Iran University of Medical Sciences, Tehran, Iran
2 Pars Advanced and Minimally Invasive Medical Manners Research Center, Affiliated to Iran University of Medical Sciences, Tehran, Iran
3 Departments of Anesthesiology, School of Medicine, Iran University of Medical Sciences, Tehran, Iran
Correspondence Address:
Seyed Mohammad Reza Mohajeri
Department of Neurosurgery, School of Medicine, Iran University of Medical Sciences, Tehran
Iran
Source of Support: None, Conflict of Interest: None
CheckDOI: 10.4103/jcvjs.jcvjs_152_22
Abstract
Atlanto-occipital dislocation (AOD) is an injury to the upper cervical spine that occurs after trauma. This injury is associated with a high mortality rate. According to studies, 8%–31% of deaths caused by accidents are due to AOD. Due to the improvement in medical care and diagnosis, the rate of related mortality has decreased. Five patients with AOD were evaluated. Two cases had type 1, one case had type 2, and two other patients had type 3 AOD. All patients had weakness in the upper and lower limbs and underwent surgery to fix the occipitocervical junction. Other complications in patients were hydrocephalus, 6 nerve palsy, and cerebellar infarction. All patients improved in follow-up examinations. AOD damage is divided into four groups: anterior, vertical, posterior, and lateral. The most common type of AOD is type 1 and the most instability is type 2. There are neurological and vascular injuries due to pressure on regional components; vascular injuries are associated with high mortality rate. In most patients, their symptoms improved after surgery. AOD requires early diagnosis and immobilization of the cervical spine along with maintaining the airway to save the patient's life. It is necessary to consider AOD in cases with neurological deficits or loss of consciousness in the emergency unit because earlier diagnosis could cause a wonderful improvement of the patient's prognosis.
Keywords: Atlanto-occipital dislocation, cranial nerve palsy, craniocervical fixation, hydrocephalus
Introduction 
Atlanto-occipital dislocation (AOD) is an injury to the upper cervical spine that occurs after trauma. This injury is usually fatal and is associated with a high mortality rate, but due to the improvement in caring for patients injured during the postaccidental period, as well as more diagnostic modalities and more experienced surgeons, the rate of related mortality has decreased. However, according to studies, 8%–31% of deaths caused by accidents are due to AOD.[1]
AOD was first described in 1908.[2] In the initial classification, AOD was divided into three categories, which included anterior (type 1), vertical (type 2), and posterior (type 3).[3] In the new classification, the lateral type was also added to it.[4] Various criteria have been created to diagnose AOD, one of which includes the following criteria; basion-dens index of more than 8.5 mm, basion-axial interval of more than 12 mm, and occipital condyle to C1 interval of more than 1.4 mm. In the presence of any of the above criteria, the patient can be diagnosed with AOD and treatment can be done.[5] Herein, we report our experience in this field with five illustrative cases concomitant with a brief literature review and explain our difficulties in management and approach to them.
Cases Report Case 1
The patient was a 46-year-old woman injured in a motor vehicle accident that was transported to the emergency room by Glasgow Coma Scale (GCS) 8 and was admitted to the intensive care unit after the condition stabilized. On the neurological examination, the paralysis of the lower limbs and right upper limb was detected. Five days later, when she had a stable clinical condition, the patient underwent craniocervical fixation surgery, and occipital plate and lateral mass screws from C2 to C4 were placed [Figure 1]. Consciousness of the patient improved after surgery. Hence, in further, neurological assessment, bilateral six nerve palsy, left facial nerve palsy, and absent of gag reflex (lower cranial nerve deficit) were observed.
The patient underwent a tracheostomy after 10 days and was then weaned. After a month, the patient was transferred to the ward. Six months later, on the assessment of the patient, she was wheelchair bound and the patient's neurological status improved. One year after the surgery, she developed an infection in the surgical site with an exposed displaced occipital plate, which was treated with replacing the one plate to the bilateral occipital-condylar screw-plate as the rostral part of fixation. Unfortunately, she died because of an unrelated cause (COVID-19 infection), 2 years later.
Figure 1: Imaging of Case 1 with type 2 AOD. The preoperative CT scans (a and b) and T2 MRI (c) in sagittal view with postoperative radiography (d). AOD: Atlanto-occipital dislocation, CT: Computed tomography, MRI: Magnetic resonance imagingCase 2
The patient is a 63-year-old man who was admitted after experiencing a car accident. In the initial evaluation, C1 Jefferson fracture (fx) was diagnosed concomitant with cerebellar. Therefore, cervical and cerebral angiography is performed for the patient, and basilar compression was observed. Two months later, due to the delayed paralysis of the upper limbs and the presence of upper motor neuron signs, cervical magnetic resonance imaging (MRI) was performed. According to MRI images, AOD type 3 was diagnosed [Figure 2]. In the cranial nerves examination, he also had a weak gag reflex (lower cranial nerves deficit).
Figure 2: Case 2 with type 3 AOD. We can see the sagittal view of MRI in STIR (a) and T2 (b) sequences. We can see the final alignment in the postoperative sagittal view of the CT scan (c). In preoperative imaging, Jefferson fracture in axial CT scan (d) and multiple cerebellar hypodensities (e) could be seen. AOD: Atlanto-occipital dislocation, CT: Computed tomography, MRI: Magnetic resonance imagingThe patient underwent surgery to fix the craniocervical junction, and the occipital plate was placed with C1 and C2 screws. He detached from the ventilator after 42 days and was transferred to the ward after 2 months. At 6 months, he was able to walk without help and his neurological symptoms improved.
Case 3
The patient was a 14-year-old man who had a car accident while cycling and had a loss of consciousness (LOC). After improving consciousness around 3 weeks after the trauma, the patient's neck was deviated and he revealed quadriparesis. Imaging study revealed a type 1 AOD [Figure 3]. The patient underwent surgery to fix the occiput-C2 by wiring concomitant with rib graft. One month after surgery, he was diagnosed with hydrocephalus, so he underwent ventriculoperitoneal (VP) shunt surgery. The syrinx in the spinal area was also diagnosed and treated with a syringe-peritoneal shunt. At 6 months later, he was able to walk without a cane and his neurological symptoms improved.
Figure 3: This figure illustrates Case 3 with type 1 AOD in preoperative reconstructed sagittal CT scan (a) concomitant with hydrocephalus (b) and final postoperation radiograph (c). Syrinx in cervicothoracic spinal cord treated with syringoperitoneal shunt (d is MRI before and e and f after shunt placement). AOD: Atlanto-occipital dislocation, CT: Computed tomography, MRI: Magnetic resonance imagingCase 4
The patient was a 34-year-old man who was admitted with GCS 6. At the time of admission, he had right hemiplegia. Computed tomographic angiography was performed with a suspicion of a stroke to evaluate vascular disorders. The patient had a negative CT angiography result. Re-evaluation of the patient's spine was performed 3 weeks later, which type 1 AOD was diagnosed [Figure 4]. The patient underwent surgery to fix the occiput to C3 through wiring and bone graft. One month after surgery, the patient developed hydrocephalus, so a VP shunt was implanted. The patient was transferred to the ward after 3 months. At 6-month follow-up, he was able to walk without help, and his neurological symptoms improved.
Figure 4: Case 4 with delayed diagnosis of type 1 AOD on axial CT scan (a). The patient underwent craniocervical fixation could be seen in lateral radiograph (b) with delayed hydrocephalus in a follow-up brain CT scan (c). AOD: Atlanto-occipital dislocation, CT: Computed tomographyCase 5
The patient was a 58-year-old man who was taken to the hospital with LOC. One month after admission, when his consciousness was improved, we re-evaluated him based on evidence of quadriparesis. Computed tomography (CT) scan showed evidence of craniocervical disorders (AOD type 3). Therefore, the patient underwent surgery to fix the neck through the occiput plate and lateral mass screws from C2 to C4 [Figure 5]. He was transferred to the ward 3 months later. At the re-evaluation of the patient, 6 months later, the patient was able to walk without help, and his neurological disorders were improved.
Figure 5: We can see Case 5 with type 3 AOD on sagittal view T2 sequence MRI (a) with acceptable reduction on the postoperation lateral radiograph (b). AOD: Atlanto-occipital dislocation, MRI: Magnetic resonance imaging Discussion AOD is associated with high mortality and majority of them are just occurred during the event. There are several reports about the survival of the patient after this fatal injury. The symptom range of patients following this injury can vary from being asymptomatic to hemiplegia in 34% and quadriplegia in 38%.[6] On the other hand, cranial nerve deficits and LOC as a sign of the severity of the injury could be accompanied with.
In our case series, all patients have paresis or plegia after trauma. Of course, the notable point in patients with AOD is late diagnosis. The AOD of 4 patients in our study was diagnosed late. Furthermore, in one case, the patient's symptoms appeared 2 months later after the injury. In the other three cases with delayed diagnosis of AOD, due to LOC, it was not possible to fully evaluate the symptoms, so after increasing consciousness and observing the long tract neurological deficits, re-evaluation revealed a craniocervical injury. In another study in 2015, five patients with AOD were examined, three patients were diagnosed on arrival, and the other two patients were diagnosed late.[5] However, according to the 2010 study, earlier diagnosis of the injury improves the prognosis of the patient.[7]
AOD damage is divided into four groups: anterior, vertical, posterior, and lateral. According to a 2004 study, the most common type of AOD is type 1.[8] Type 2 had the most instability and type 3 was the rarest type of AOD.[3] One of our patients was type 2 who had more symptoms than other patients and her symptoms improved with a longer delay. Two cases had type 1, one case had type 2, and two other patients had type 3 AOD.
This injury can be associated with other injuries throughout the spine. Jefferson fracture and syrinx of the cervical cord were among the injuries associated with in the patients of this study. In AOD, there are neurological injuries due to pressure on the brain stem and spinal cord, as well as vascular injuries, including injuries to the carotid and vertebral arteries; vascular injuries are associated with high mortality rate.[8] Furthermore, brain damage can also be seen in these patients. Two patients from our series had delayed hydrocephalus and one of them had cerebellar infractions due to basilar compression. In another study, a 6-year-old boy diagnosed with AOD developed hydrocephalus 3 months after treatment, for which a peritoneal shunt was implanted.[9] 6th cranial nerve damage is also a rare complication that has been reported in three previously reported cases.[8],[10],[11] Furthermore, in our study, one patient had bilateral sixth nerve palsy and damage to the left trigeminal nerve concomitant with gag reflex disturbance. Another patient also suffered from weak gag reflex and his symptoms improved during the treatment.
All patients of the present case series underwent occiput to cervical fixation surgery. In other studies, the treatment was divided into two categories: nonsurgical treatment and surgical treatment. Patients with lesser instability underwent nonsurgical treatment (10.8%) and more unstable patients underwent surgical treatment (56.5%);[12] in these studies, the occiput was fixed to the neck and the caudal end of fixation placed in a range from C2 to C7.
In most patients, their symptoms improved after surgery. On follow-up, four patients of this study were able to walk without using cane. One patient was wheelchair bound after surgery and discharge from the hospital. In other studies, we can see the improvement of symptoms after treatment.
Considering the radiography and MRI examination of reported patients in the literature, the paravertebral soft-tissue swelling observed that its amount was 17.88 mm as the mean value.[5] In one of our patients, this tissue became swollen and its thickness was 14.98 mm. In another study, preservation of the tectorial membrane was considered a positive prognostic factor for patients with AOD;[13] case 1 in our report who had AOD type 2 with most symptoms, it seems that the tectorial membrane was healthy on the MRI examination, and her symptoms improved significantly during the treatment process. All patients in this study survived after treatment. Our case 1 died during the follow-up around 2 years after surgery due to the COVID-19 virus pandemic.
In general, AOD is the lethal event just at the time of injury. The number of reported posttraumatic alive patients with AOD is low. Knowing how faced with this injury at the occurrence and during the transferring the patient and informing the emergency personnel about this possible disaster could increase the chance of the survival with least disabilities after precise treatment planning.
Conclusion AOD is considered a potentially fatal disease, which requires early diagnosis and immobilization of the cervical spine along with maintaining the airway to save the patient's life. Due to the possibility of delayed diagnosis, it is necessary to consider AOD in cases with neurological deficits or LOC in the emergency unit. As an accepted matter, AOD type 2 is considered the most unstable type and it shows more severe symptoms but earlier diagnosis same our case 2 could cause wonderful improvement of the patient's prognosis.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.
Financial support and sponsorship
Nil.
Conflicts of interest
There are no conflicts of interest.
References 
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