Petrous bone fractures

Symptom: Unilateral Hearing Loss

A 45-year-old man presented to the emergency department (ED) after falling down two flights of stairs. He had bilateral raccoon eyes, subconjunctival haemorrhages and CSF otorrhoea suggestive of skull base fracture (SBF). Although he had difficulty speaking and responded inappropriately, giving the impression of mixed dysphasia, written communication was normal, and he complained of deafness and dizziness. Facial motion was barely perceptible and complete eye closure was not possible, consistent with grade 5 facial palsies on the House-Brackmann facial nerve grading system. Bell’s phenomena (Fig. 1) and dysarthrophonia secondary to facial weakness were marked. He was also mildly ataxic. Computed tomography (CT) imaging confirmed extensive SBF and audiometric testing confirmed bilateral deafness. High-resolution axial petrous temporal bone CT (Fig. 2) demonstrated fractures involving the facial canals. The right-sided fracture traversed the fundus of the internal auditory canal, likely transecting the cochlear nerve, and the left-sided fracture involved the otic capsule, likely disrupting auditory and vestibular function. Fig. 1 a A 45-year-old man with facial diplegia. b Patient attempting to close both eyes producing bilateral Bell’s phenomenon. c Magnification of b demonstrating marked bilateral Bell’s phenomenon (more pronounced on the right side) Fig. 2 Right and left axial petrous temporal bone CT. Right axial CT shows a medial subtype of horizontal temporal bone fracture. There is a fracture of the posterior petrous surface (white arrow) extending anteriorly through the fundus of the internal auditory ... Post-traumatic facial nerve palsy complicates 1.5% of SBFs involving the temporal bones [1]. Petrous temporal bone fractures may disrupt the facial nerve, membranous labyrinth and inner ear. While cranial nerves seven and eight may be injured by petrous temporal bone fractures, concomitant bilateral facial weakness and deafness in this setting is extremely rare [2]. Most post-traumatic facial nerve injuries recover with conservative management and time [3, 4]. This case illustrates how bilateral facial weakness and deafness may be mistaken for mixed dysphasia and highlights the need to consider it in patients with apparent speech disturbances in the ED.

Introduction: Cholesteatoma of the petrous bone is a rare pathology that grows slowly and is often asymptomatic. Material and Methods: The clinical records of a patient with congenital petrous bone cholesteatome managed surgically in our department were reviewed retrospectively. Results: A 57-year-old man was referred to our department with a 1-month history of sudden left total facial nerve palsy. He has a 30 years history of left-sided hearing disturbance without otorrhea. On physical examination, he showed a normal tympanic membrane, vestibular function was normal, facial examination presented a facial nerve paralysis of grade VI. The audiogram revealed severe sensorineural hearing loss on one side. CT scans revealed a soft tissue density lesion that extended widely from the anterior tympanic cavity to the petrous bone. MRI revealed a lobulated mass with its center at the petrous temporal bone. The lesion had low signal intensity on T1WI images and high signal intensity on T2WI images. We diagnosed a congenital cholesteatoma of the left petrous bone origin and performed surgery. We performed a translabyrinthine approach. The patient's postoperative cochlear function was not preserved. Course was uncomplicated. Conclusion: Congenital cholesteatoma is suggested to arise from epithelial cell rest within the temporal bone. Its slow silent growth may remain asymptomatic for years and cause delay in treatment. It may also involve all the vital anatomical structures within the temporal bone.

ObjectivesChronic Nonbacterial Osteomyelitis (CNO) is an autoinflammatory disorder of bone typically beginning children between the ages of 7-12. Any bone can be affected, involvement of the skull is unusual and petrous bone involvement has not been reported. The objective of our study is to illustrate presenting features associated with CNO of the petrous temporal bone, its treatment, and response to therapy. The second is to increase awareness that CNO can involve the petrous temporal bone with the hope it will aid in diagnostic clarity for challenging cases.MethodsCases of patients diagnosed with CNO between June 2002-May 2022 at The Hospital for Sick Children were identified by searching Bialogics and the Electronic Medical Record Epic. Charts were searched for the term “skull” to identify cases affecting the skull. To obtain records prior to 2018 we ran a word search of pertinent synonyms to identify cases of CNO involving the temporal bone in the ISYS imagining system. Research Ethics Board approval was obtained.ResultsThree cases of CNO affecting the petrous temporal bone, were identified (Figure 1). All had known CNO peripheral lesions. They ranged in age from 2-10 years old and were female. Two patients had 7th cranial nerve involvement and hearing loss. All patients were treated with a non-steroidal anti-inflammatory drug (NSAID) and 2 patients with hearing loss received anti-TNF therapy (adalimumab) and responded well with resolution of hearing loss in 1 case and residual mild to moderate conductive hearing loss in another. These cases are unique as they involve the skull, a less affected CNO site.[1,2] It typically affects metaphysis and epiphyses of the long bones, vertebral bodies, and the clavicle. Axial skeletal involvement is less prevalent (61%) compared to appendicular skeleton involvement (75%).[2] With 1% of patients presenting with skull lesions.[1,2] It is unknown why CNO rarely affects the skull. Theories include CNO tends to affect the metaphysis and epiphyses of the long bones which the skull does not have. Another is there is increased metabolic activity at the epiphysis with chondrocyte maturation which could result in increased propensity of immune dysregulation and inflammatory lesions.[3]ConclusionCNO typically affects the metaphysis of the long bone but can affect any bone in the body, including the temporal petrous bone of the skull. It is important to consider CNO on the differential in patients who present with cranial nerve abnormalities, facial nerve palsy, hearing loss, and those with presumed infectious osteomyelitis. [1.] Ferrara G. Clin Exp Rheumatol 2020;38(2):366-9. [2.] Borzutzky A. Pediatrics 2012;130(5):e1190-7. [3.] Shapiro IM. 2007;40(3):561-7.Best Abstract on Pediatric Research by Early Career Faculty Award

Total external ophthalmoplegia and orbital apex syndrome as first presenting feature of Rhabdomyosarcoma involving petrous part of the temporal bone: A case report

Background: Arcuate eminence (AE) is an arc-like elevation seen on the anterior surface of petrous part of temporal bone in the middle cranial fossa (MCF). It has been believed and conventionally taught that AE is a protrusion caused because of the superior semicircular canal (SSC) present in the petrous bone. AE is an useful anatomical landmark in the MCF during surgical approaches to acoustic neuroma through suprapetrosal approach. However, the relevance of relation to AE and SSC has been questioned in recent times. Presence of AE of various shapes and dimensions supports this view. Aim: To study and to establish the relation between shape of AE and inferior surface of cerebral hemispheres. Classify various types and subtypes in case of variation in shape based on its appearance. AE could be a negative impression of either gyrus or a sulcus. Material and Methods: The study was conducted in two parts. In the first part, the shape of AE and the impression on cerebral surface were correlated while removing brain from cranial cavity in 8 cadavers (16 wet temporal bones). In second part of the study, 100 dry temporal bones were examined. Relevant photographs were taken. A total of 116 temporal bones were studied. AE was classified as linear, globular, generalized swelling, and flat based on the appearance. Results and Conclusion: 10 AE of 16 wet temporal bones were linear type and did correspond with a sulcus, whilein 1 cadaver no relation was seen. In dry bones, maximum linear variety was seen. There was no relation to shape of AE and cerebral surface in two cadavers. Diversity in shapes, (linear type 47%) and correlation with sulci on cerebral surface contests the earlier understanding that AE is due to SSC. Thickness of bone over SSC was not measured in this study. Having seen so many shapes of AE in this study, authors are of the opinion that there is a need to revisit this bony landmark in MCF and rethink if it can be used as a guide in middle canial fossa surgeries. This study, however, did not look into the bony thickness overlying SSC, which could have added the knowledge of depth of SSC from bony surface of petrous apex.

The extraction of the cochlea from a cadaver human temporal bone may be required for different studies of the inner ear. For histological evaluations, the inner ear must be extracted from the temporal bone to facilitate histologic processing; likewise, some micro-computed tomography devices are too small to accommodate the complete temporal bones; additionally, the image quality can be enhanced when the cochlea is isolated. The inner ear is located within the petrous part of the temporal bone. The inner ear can be divided into the osseous labyrinth or otic capsule and the membranous labyrinth inside the otic capsule. Furthermore, the inner ear can be divided into the vestibular system (the semicircular canals and the vestibule) and the cochlea. The appreciation of the location and orientation of the cochlea within the temporal bone is difficult, as it is embedded within bony structures and thus cannot be directly visualized. Nevertheless, there are distinct anatomical structures that can help guide the process to allow a reliable drill-out of the cochlea. The landmarks in the posterior parts of the cochlea are the facial nerve, semicircular canals, and the vestibule. In the middle, the inferior borders of the cochlea are identified by the round window and the basal turn of the cochlea. In the anterior border, one encounters the carotid artery; the landmark for the superior border is the genicular ganglion (GG) of the facial nerve. The medial structures are determined by the locations of the internal auditory canal, the superior semicircular canal, and the canal of the internal carotid artery. In this article, we present a method for extracting the cochlea reliably out of the temporal bone by drill-out while following several anatomical landmarks.

The temporal bone is one of the most difficult bones for students in head and neck courses to learn. These paired bones help form the base and lateral walls of the skull in addition to housing the auditory and vestibular apparatus. Each temporal bone has eight centers of ossification which give rise to the three major centers which are observed prior to birth. There are four major parts of the temporal bone: the squamous, petrous, tympanic, and styloid process. The squamous and tympanic portions develop from intramembranous bone formation whereas the petrous portion and styloid process develop from endochondral bone formation. The temporal bone is very complex, as it also houses the internal jugular vein, internal carotid artery, facial nerve and branches, and the vestibulocochlear nerve. However, these structures are lost in disarticulated bones. While the anatomy of the temporal bone can be appreciated from the disarticulated skull, the internal anatomy of the bone is difficulty to observe unless careful dissection is performed. The iCAT cone beam scans allow for 3 dimensional reconstruction of the skull. In our study, we performed iCAT cone beam scans on both disarticulated temporal bones and cadavers to reconstruct the anatomy of the temporal bone for instruction to dental students. This imaging technique allowed us to teach the clinical anatomy of the temporal bone including the auditory ossicles and semicircular canals in situ. Canals such as the internal acoustic meatus, external meatus, and facial canal were easily traced to explain the path of internal structures. This imaging modality serves as an excellent adjunct in learning the anatomy of the temporal bone.

Objective The purpose of this study was to dissect these structure existed in petrous portions of the temporal bones and the posterior fossa nearby,to measure the distence of those important stuctures around the superior petrosal venous (SPV), to propose the patterns of drainage of the SPV along the petrous ridge in relation to the Meckel cave and internal acoustic meatus (IAM) and to delineate its effect on the surgical exposures obtained in subtemporal transtentorial and retrosigmoid suprameatal approaches. Methods Ten adult cadaveric heads (20 hemispheres) were studied, and data of SPV and the structures around were measured. The patterns of drainage of the SPV along the petrous ridge were characterized according to their relation to the Meckel cave and the IAM based on an examination of 20 hemispheres. Subtemporal trans-tentorial and retrosigmoid suprameatal approaches were performed in two additional cadavers to demonstrate the effect of the drainage pattern on the surgical exposures. Result The SPV originated from the cerebellopontine angle cistern, and were multibranch. According to SPV relationship with the Meckel cave and internal acoustic meatus (IAM), the patterns of drainage of the SPV were classified into three groups. Type Ⅰ emptied into the SPS above or medial to the Meckel cave. The most common type-Type Ⅱ, emptied between the lateral limit of the trigeminal nerve at the Meckel cave and the medial limit of the facial nerve at the IAM. Type Ⅲ emptied into the SPS above and lateral to the boundaries of the IAM Conclusions The site which the SPV emptied into the superior petrosal sinus (SPS) was relationship tightly with the Meckel cave and IAM. According to SPV relationship with the Meckel cave and internal acoustic meatus (IAM). The proposed modified classification system and its effect on the surgical exposure may aid in planning the approach directed along the petrous apex and may reduce the probability of venous complications. Key words: Superior petrosal vein; Superior petrosal sinus; Retrosigmoid approach; Subtemporal approach

Analysis of temporal bone thickness outside of the petrous temporal bone between superior semicircular canal dehiscence and normal patients

Ramsay Hunt syndrome is defined as herpes zoster oticus associated with an acute peripheral facial nerve paresis and quite often with other cranial nerve lesions. The combination of motor, sensory and autonomic involvement leads to a variety of neurological damage patterns, i. e. facial muscle paresis, hearing and balance disorders, sensory problems and disturbances of taste as well as lacrimal and nasal secretion. Additional variability of the clinical picture of Ramsay Hunt syndrome is produced by varying patterns of skin involvement explained by individual anastomoses between cranial and cervical nerves. Knowledge of these findings and an early diagnosis of Ramsay Hunt syndrome are important as prognosis of cranial nerve damage depends on the time at which acyclovir-corticosteroid therapy is started.

Objective To establish standard sites for bur holes that maintain constant anatomical relationships with the skull base and neural structures and can serve as the basal aspect of supratentorial temporooceipital craniotomies such as subtemporal transpetrosalridge approach.Methods To determine cranial-cerebral relationships,the authors delimited 10 adult cadaveric skulls anteriorly and posteriorly the external projection of the petrous bone and the midbrain by CT and Titanium nail.Then bur holes in adult cadaveric skulls were created (kl,the first bur hole,located anterior to the auricle of the ear; k2,the second bur hole,whose base was located 1 cm above the interface of the parietomastoid and squamous sutures; k3,the third bur hole whose base was located 1cm above the asterion).Three bur holes were made on each of the skulls (20 cerebral hemispheres).The author then introduced plastic catheters through the bur holes to evaluate pertinent cranial and neural landmarks.Results The first bur hole appeared to have a particular anatomical relationship with the anterior aspect of the petrous portion of the temporal bone and the most anterior aspect of the midbrain.The second bur hole had a particular relationship with the posterior border of the petrous portion of the temporal bone and with the posterior aspect of the midbrain.The third bur hole was mostly supratentorial and particularly related to the preoccipital notch.Conclusions The middle fossa floor is located anterior to the site of the kl,and the superior surface of the tentorium is posterior to k2.Together with k3,these bur holes can be considered standards for temporooccipital craniotomies such as subtemporal transpetrosalridge approach. Key words: External projection; Skull base; Subtemporal transpetrosalridge approach; Anatomy

The purpose of this study was to establish guidelines that help radiation oncologists contour the inner and middle ear on treatment planning scans. The radiotherapy computed tomography (CT) scans of 15 previously treated patients were reviewed for the ability to identify 3 separate auditory structures. The middle ear, the cochlea, and the vestibular apparatus were identified and contoured on each scan using anatomic landmarks. The volume and maximum axial dimension of each contour were calculated. The middle ear, cochlea, and vestibular apparatus were identified on all scans. The middle ear was defined by the tympanic membrane laterally and by the interface between air and the temporal bone in all other directions. The plane of the internal auditory canal through the temporal bone was the landmark distinguishing the vestibular apparatus from the cochlea. The mean volume of the middle ear, vestibular apparatus, and cochlea were 0.58 cm3, 0.44 cm3, and 0.14 cm3, respectively. The maximum axial dimension across the contour averaged 1.57 cm for the middle ear, 1.10 cm for the vestibular apparatus, and 0.69 cm for the cochlea. A reference atlas was constructed that shows the contour of each structure on 5 consecutive CT images. Accurate identification of the middle ear and inner ear structures on radiotherapy planning scans is possible and is necessary if critical auditory organs are to be spared during radiotherapy of targets that are located near the base of the skull. The information generated in this study will help radiation oncologists contour auditory structures accurately.

The temporal bone consists of four components: the squamous, petromastoid and tympanic portions, and the styloid process. The petrous part houses the auditory apparatus1. This mass of bone is wedged between the sphenoid and occipital bones in the cranial base1. Complete agenesis of the petrous portion of the temporal bone occurs in Michel aplasia2, a congenital malformation associated with congenital hearing loss. Here we describe, for the first time, the sonographic appearance of the petrous part of the temporal bone in normal pregnancies, between 14 and 16 weeks of gestation, using transvaginal sonography (TVS). Approval for the study was given by the Institutional Review Board (Helsinki Committee Protocol). Thirty-four consecutive pregnant women, between 14 and 16 weeks of gestation, were examined after giving written informed consent to take part in the study. All patients were studied during a routine fetal anomaly scan using TVS, with an endocavitary 5–9-MHz transducer (Voluson 730 Expert; GE Medical Systems, Milwaukee, WI, USA). Patients were included in the study if there was a single fetus without evident or suspected fetal malformations and no family history of congenital hearing loss. The fetal head was assessed in transverse sections with the parotid gland first identified as an echoic structure located medial to the external ear; the petrous bone (an annular echogenic structure located medial and superior to the parotid gland) was then identified and measured in its largest anteroposterior diameter (Figure 1, Videoclip S1). The largest of three measurements was documented. The petrous bone was measured on at least one side of the head in each fetus. The examination time was not prolonged in order to permit measurement of the petrous bone (beyond the short time needed for the measurement itself) and no special attempt was made to measure the bone on both sides. However, bilateral measurements were obtained when both sides were visualized easily. Measurement of the petrous bone (calipers) at 15 weeks of gestation. Ant., anterior; Post., posterior; E, eye. In all 34 fetuses the petrous bone was visualized and measured on at least one side, and in eight patients the petrous bones were visualized and measured bilaterally. The median anteroposterior diameter of the petrous bone was 4.5 (range, 3.5–6.1) mm, and the mean ( ± SD) anteroposterior diameter was 4.59 ± 0.53 mm. This is the first report to describe the normal appearance of the fetal petrous bone. The ability to visualize the petrous bone raises the possibility of prenatal diagnosis of congenital malformations of the inner ear, such as Michel aplasia2. Congenital hearing loss owing to malformation of the inner ear is classified into several types3-5. Some of these malformations are associated with malformations of the temporal bone, specifically the petrous portion, which is reported to be malformed in about 20% of cases of congenital deafness4. We measured the petrous bone at 14–16 weeks of gestation because at later gestational ages measurement of the bone is more difficult and time-consuming. However, we now measure the normal petrous bone at up to 40 weeks of gestation. TVS was used because this is the standard technique used in our institution for a routine fetal anomaly scan at the gestational age considered. However, the petrous bone can also be visualized using transabdominal transducers at 14–16 weeks. SUPPORTING INFORMATION ON THE INTERNET The following supporting information may be found in the online version of this article: Videoclip S1 Videoclip showing measurement of the petrous bone in a 15-week fetus. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article. M. Odeh*, E. Ophir*, J. Bornstein*, * Department of Obstetrics and Gynecology, Western Galilee Hospital, Nahariya, Rappaport Faculty of Medicine, Technion, Haifa, Israel

The extradural anterior petrosectomy approach to the pons and midbasilar artery (mid-BA) has the main disadvantage that the extent of resection of the petrous apex cannot be as minimal as desired given that the surgical target field is not visible during bone removal. Unnecessary or excessive drilling poses the risk of injury to the internal carotid artery, vestibulocochlear organ, and seventh and eighth cranial nerves. The use of a custom-tailored transdural anterior transpetrosal approach can potentially avoid these pitfalls. A technique for a transdural anterior petrosectomy was developed in the operating theater and anatomy laboratory. Following a subtemporal craniotomy and basal opening of the dura mater, the vein of Labbé is first identified and protected. Cerebrospinal fluid ([CSF] 50-100 ml) is drained via a spinal catheter. The tent is incised behind the entrance of the trochlear nerve toward the superior petrosal sinus (SPS), which is coagulated and divided. The dura is stripped from the petrous pyramid. Drilling starts at the petrous ridge and proceeds laterally and ventrally. The trigeminal nerve is unroofed. The internal acoustic meatus is identified and drilling is continued laterally as needed. The bone of the Kawase triangle toward the clivus can be removed down to the inferior petrosal sinus if necessary. Anterior exposure can be extended to the carotid artery if required. It is only exceptionally necessary to follow the greater superior petrosal nerve toward the geniculate ganglion and to expose the length of the internal acoustic canal. The modified transdural anterior petrosectomy exposure has been used in nine patients-two with a mid-BA aneurysm, two with a dural arteriovenous fistula, one with a pontine glioma, three with a pontine cavernoma, and one with a pontine abscess. In one patient with a mid-BA aneurysm, subcutaneous CSF collection occurred during the postoperative period. No CSF fistula or approach-related cranial nerve deficit developed in any of these patients. There was no retraction injury or venous congestion of the temporal lobe nor any venous congestion due to the obliteration of the SPS or the petrosal vein. The custom-made transdural anterior petrosectomy appears to be a feasible alternative to the formal extradural approach.