Isolated traumatic retroclival hematoma: case report and review of literature

Background Retroclival hematomas are a rare entity. The pathology can be categorized into epidural hematoma or subdural hematoma based on the anatomy of the tectorial membrane. Frequently, the etiology is related to accidental trauma, though other mechanisms have been observed, including coagulopathy, non-accidental trauma, and pituitary apoplexy. There have been only 2 prior cases where both epidural and subdural hematoma co-present. Case presentation An 8-year-old male was involved in a high-speed motor vehicle accident. He presented with a Glasgow Coma Score (GCS) of 14 with bilateral abducens nerve palsies. Computed tomography (CT) revealed a hemorrhage along the dorsum sella, clivus, and dens. Magnetic resonance imaging (MRI) demonstrated the retroclival hematoma in both the subdural and epidural space. At discharge, 19 days after the accident, the abducens nerve palsies had resolved without medical or operative intervention. Conclusion Retroclival hematoma may present after trauma. Although most cases exhibit a benign clinical course with conservative management, significant and profound morbidity and mortality have been reported. Prompt diagnosis with close observation is prudent. Surgical management is indicated in the presence of hydrocephalus, symptomatic brainstem compression, and occipito-cervical instability.


Introduction
Retroclival hematomas are rare and only represent a small subset of posterior fossa extra-axial hematomas, which as a whole constitute approximately 0.3 % of acute extra-axial hematomas [1,2]. The pathology can be categorized into epidural hematoma (rcEDH) or subdural hematoma (rcSDH) based on the anatomy of the tectorial membrane. Most cases in the literature involve the pediatric population, though few cases have been reported in the adult population as well. Frequently, the etiology is related to accidental trauma, though other mechanisms have been observed, including coagulopathy, non-accidental trauma, pituitary apoplexy, and ruptured aneurysm. Still, some remain spontaneous without an identifiable cause [3][4][5][6][7][8]. We report a pediatric patient who sustained a retroclival hematoma (with both subdural and epidural components) after a motor vehicle crash and provide a review of the available English literature, emphasizing the pathophysiology of injury and the appropriate clinical management. There have been only 2 prior cases where both epidural and subdural hematoma co-present [9].

Case presentation
An 8-year-old male was involved in a motor vehicle crash. He was sitting on the back seat along the driver side; his seat belt status was unknown. The vehicle was BT-boned^by another vehicle traveling 60 miles per hour. At the scene, patient exhibited a GCS 14. On presentation, his eyes were crossed, but he did not complain of diplopia until the following day. Because he was lethargic and confused, he was admitted to the ICU for close monitoring. He denied significant headaches, blurred vision, eye pain, or light sensitivity. Physical examination was significant for bilateral 6th nerve palsies.
CT of the head revealed a hemorrhage along the dorsum sella, clivus, and dens (Fig. 1a, 1b). MRI brain and cervical spine were obtained to evaluate the hematoma and the craniocervical junction for signs of instability; the retroclival hematoma appeared in the subdural space and epidural space; there was T2 hyperintensity in atlanto-occipital joints and blood along the tectorial membrane (Fig. 2a, 2b). Subsequently, cervical spine flexion/extension x-rays were obtained, which demonstrated no instability and the cervical collar was discontinued. The patient had a prolonged hospitalization due to a duodenal hematoma and associated feeding issues. At discharge, 19 days after the accident, he exhibited intact eye movements.

Discussion
Retroclival subdural hematoma (rcSDH) has been reported less often than epidural hematoma (rcEDH). However, both can co-present, particularly in violent injuries [10]. Tables 1, 2, 3, and 4 summarize the available English literature. In the pediatric population, there have been 30 cases of rcEDH and 16 cases of rcSDH; in the adult population, there have been 8 cases of rcEDH and 21 cases of rcSDH. The tectorial membrane helps define the distinction between the epidural space and the subdural space, where the former is ventral to the membrane and the latter is dorsal to the membrane [11]. The tectorial membrane is the rostral continuation of the posterior longitudinal ligament, attached inferiorly to the posterior body of the axis and superiorly to the occipital bone along the clivus [11]. RcEDH are restricted by the boundaries of the membrane (that is, from the mid-portion of the clivus to the middle of the body of the axis); rcSDH are not restricted and can disseminate from the intracranial to the spinal subdural space [11]. The MRI (Fig. 2a, 2b) from our patient demonstrated stripping of the tectorial membrane, with focal areas of disruption; the ventral fluid collection tracking down to the mid body of the odontoid is consistent with an epidural hematoma; however, there is also a collection that exists posterior to the tectorial membrane and tracks more inferiorly to the posterior of the C3 body; this collection is consistent with a subdural collection.
The most common etiology is a traumatic event that induces hypermobility of the neck. Either hyperflexion or hyperextension can lead to soft tissue injury or fractures, causing a retroclival hematoma. The preponderance of reported pediatric cases relative to adult cases may be attributed to the anatomical differences at the craniocervical junction. Compared to adults, children possess certain features (large head-to-body proportion, small occipital condyles, shallow facet joints, and weak cervical muscles) that increase the mobility of the spine and augment the risk for injury [12,13]. Disruption of the tectorial membrane (i.e., from its insertion into the clivus) can cause venous bleeding from the surrounding basilar venous plexus and dorsal meningeal branch of the meningohypophyseal trunk, leading to an epidural collection [11]. In children, the dura can be more easily detached from the bone, which makes them more vulnerable to forceful traction [14]. Clival fractures have been associated with rcEDH, likely due to bone bleeding as well as injury to the tectorial membrane [15,16]. Similarly, odontoid fractures have been reported; dislocation of the dens can cause damage to the transverse ligament and traction to the tectorial membrane, prompting hemorrhage [17,18]. Shearing forces may lead to rcSDH via rupture of the bridging petrosal and small veins near the foramen magnum; the tectorial membrane is usually unharmed, remaining attached to the clivus; this feature is an important characteristic which differs from rcEDH [11]. Other traumatic injuries associated with retroclival hematoma include atlanto-occipital dislocation [19,20], atlanto-axial dislocation, rupture of the transverse ligament [17], fractures of the occipital condyles [21], spheno-occipital synchondrosis diastasis [22], brain stem contusion [17], and intraventricular hemorrhage [17].
These hematomas may be overlooked on axial CT due to beam hardening artifacts in the posterior fossa [16], requiring reformatted CT images or MRI to elucidate the diagnosis and assess for ligamentous damage. Common etiologies can typically be inferred based on clinical presentation (history of trauma or presence of pituitary adenoma). Work-up for concurrent blunt traumatic vascular injury may be warranted. With no obvious mechanism, work-up for vascular pathology or coagulopathy should ensue [28]. The presence of ligamentous instability and brain injury or spinal cord injury will determine the appropriate management [11]. The possibility of brainstem compression or instability mandates initial close observation, reasonably within an ICU setting [30]. Although rare, the extra-axial hematoma can cause mass effect on the brainstem and cranial nerves, necessitating surgical evacuation [19,35,37,38]. Of the 33 traumatic cases of rcEDH, twelve patients exhibited a cranial nerve palsy, five patients required surgical stabilization of the craniocervical junction [19,38,39], one patient required an external ventricular drain for progressive hydrocephalus [20], and six patients died. Of the 17 traumatic cases of rcSDH, no patient required surgical stabilization; one patient died. Of the 12 cases of pituitary apoplexy, all but 1 patient exhibited cranial nerve palsies; overall, surgical resection of the hemorrhagic pituitary adenoma has led to good outcomes [1,24].
Except for the rare cases that lead to death [17,18,20,28,29,37,39], the majority of patients exhibit good outcomes with minimal long-term neurological deficits with conservative management. Tubbs et al. [39] noted no relationship between hematoma size and presenting symptoms; moreover, initial GCS did not correlate with outcomes. Hematoma appears to resolve within 2-11 weeks [14,36,39]. On admission, our patient exhibited bilateral 6th nerve palsies, consistent with prior reports. At discharge, 19 days after the accident, he exhibited intact eye movements. Flexion and extension films demonstrated no cervical instability, and his cervical spine was cleared.

Conclusion
Retroclival hematoma may present after trauma. Most cases exhibit a benign clinical course with conservative management, but significant and profound morbidity and mortality have been reported. Prompt diagnosis with close observation is prudent. Surgical management is dictated based on the presence of hydrocephalus, brainstem compression, and occipitocervical instability.