Facial Canal Research Articles

High-Resolution Computed Tomography and Intraoperative Correlation in Cholesteatoma: Enhancing Preoperative Evaluation and Surgical Management.

Cholesteatoma, a hazardous non-neoplastic lesion of the temporal bone, is prevalent in socio-economically disadvantaged groups in developing nations like India. Timely detection and surgical intervention are essential for effective management. High-resolution computed tomography (HRCT) has revolutionized the assessment of temporal bone pathology, though its role in preoperative evaluation remains debated. This study aimed to validate HRCT's utility in diagnosing cholesteatoma, compare its findings with intraoperative observations, and assess sensitivity and specificity. This diagnostic accuracy study was conducted at a tertiary care center in Western India, from March 2021 to November 2022. HRCT findings of 54 cholesteatoma patients were evaluated and compared with intraoperative findings. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), accuracy, and Cohen's kappa coefficient were calculated. HRCT demonstrated a sensitivity exceeding 90% in identifying scutum erosion, mastoid sclerosis, and abnormalities in the tympanic membrane, along with a specificity surpassing 90% in detecting various conditions, including facial canal erosion, sinus plate erosion, lateral semicircular canal erosion, erosion of the posterior wall of the external auditory canal, and abnormalities in the tympanic membrane. Furthermore, HRCT exhibited an accuracy of over 90% in detecting most pathologies. There was a perfect or near-perfect agreement observed for abnormal tympanic membrane, sinus plate erosion, mastoid sclerosis, and erosion of the posterior wall of the external auditory canal (with kappa values > 0.8). Moderate to fair agreement was noted for other pathologies. HRCT offered precise detection of the majority of pathologies, thereby facilitating surgical planning. However, the presence of limitations in distinguishing specific abnormalities highlights the significance of utilizing HRCT in tandem with other diagnostic modalities to ensure meticulous diagnosis and effective treatment planning.

A Case of Giant Petrous Apex Cholesteatoma With Pseudomonas Aeruginosa Infection.

Petrous apex cholesteatoma is a relatively rare and chronic aggressive disease that occurs in the petrous part of the temporal bone and can be classified as congenital or acquired. Due to the tendency of petrous cholesteatomas to cause bone destruction and invade important structures such as the facial nerve, cochlea, and semicircular canal, patients present mainly with severe hearing loss, progressive peripheral facial palsy, vertigo, etc. When the lesion invades the intracranial region or is infected, intracranial symptoms such as meningitis, lateral sinus thrombosis, and brain abscess may be present. We report a case of giant petrous cholesteatoma with Pseudomonas aeruginosa infection, with the aim of exploring the corresponding clinical treatment and surgical modalities to provide a reference for the clinical management of this type of disease.

Transmastoid Facial Nerve Decompression for Craniometaphyseal Dysplasia.

We document the first successful transmastoid surgical treatment of facial nerve palsy for a patient with craniometaphyseal dysplasia (CMD), a rare genetic disease. A 9-month-old girl with bilateral facial nerve palsies and conductive hearing loss. Genetic testing made a diagnosis of CMD, and imaging showed narrowing of the facial nerve canals and ossicular fixation. Right transmastoid facial nerve decompression and ossicular chain reconstruction. Facial nerve function (House-Brackmann grade). Facial nerve function initially worsened, then improved within 12 months from House-Brackmann grade IV-V to grade III. Surgical cranial nerve decompression of and ossicular chain reconstruction may be effective treatments for patients with CMD.

Managing cholesteatomas with labyrinthine fistula.

A retrospective study (2011 to 2018) was conducted to evaluate the management of cholesteatomas with labyrinthine fistulae (LFs), clinical characteristics and postoperative hearing outcomes in a hospital. Demographic data of patients with primary middle ear mastoidectomies for cholesteatoma were extracted. Preoperative high-resolution computed tomography (HRCT) temporal bone and intraoperative findings, and hearing levels preoperatively and postoperatively were evaluated. Of the middle ear cholesteatomas, 15.6% (n = 14) of ears were complicated by LF. HRCT scans showed 92.9% sensitivity and 94.7% specificity in the identification of LFs. Intraoperative findings of LFs include stapes erosion (78.6%), malleus erosion (78.6%), incus erosion (92.9%), dehiscence of tegmen tympani (28.6%) and tympanic facial canal (64.3%). Compared to the non-LF group, the LF group showed significantly higher incidence of stapes erosion (P < 0.001), tegmen tympani dehiscence (P = 0.016) and semicircular canal dehiscence (P < 0.001). Matrix was removed completely in 85.7% (n = 12) and was left behind in 14.3% (n = 2) of ears. Also, 21.5% (n = 3) had preoperative dead ears. Postoperative hearing results had a mean follow-up time of 2.1 (standard deviation 1.5, range 0.14-4.84) years. In the matrix removal group (n = 9), 77.9% had unchanged hearing levels, 11.1% showed improvement and 11.1% showed decrease in hearing levels. The matrix preservation group (n = 2) had deteriorated hearing levels. Preservation of hearing in LFs is possible with cautious matrix removal. Despite matrix preservation to preserve hearing in large LFs, our patients' hearing deteriorated postoperatively. Longer follow-up of hearing with matrix preservation may show poorer hearing outcomes.

Total Transcanal Endoscopic Ear Surgery for Cholesteatoma.

This study aimed to evaluate the outcomes of total transcanal endoscopic cholesteatoma surgery. Twenty-seven cholesteatoma patients that had undergone transcanal endoscopic ear surgery (TEES) were included in the study. Age, sex, operation date of patients, operated side, need for ossiculoplasty, graft material, and surgical technique were recorded. All patients were evaluated through otoscopic, endoscopic, and audiological examinations and followed up for at least five months after surgery. All patients were staged using the European Academy of Otology and Neurotology/Japan Otological Society (EAONO/JOS) Staging System on Middle Ear Cholesteatoma. Mean age of the patients was 36.4 years (range, 4-67 years). According to the EAONO/JOS Staging System, 11 patients were stage 1, while 11 were stage 2, and five were stage 3. Two had lateral semicircular canal defect, one had facial canal dehiscence, and one had oval window defect. The average follow-up period was 19 months (range, 5-41 months), during which two patients experienced retraction pocket and hearing loss and one patient had perforation. One patient underwent revision surgery during follow-up and no recurrence or residual cholesteatoma was observed. The preoperative and postoperative air-bone gaps were 25.14±13.93 dB and 22.22±12.64 dB with no significant difference. TEES is a minimally invasive and safe procedure with low complication and recurrence rates. As with all surgical procedures, experience is essential, and as experience increases, the capability to perform endoscopic otologic surgery on more complex cases may become possible.

Variation of the stapes and its surrounding anatomical structures based on micro-computed tomography.

Stapedotomy is the most efficient treatment for otosclerosis. The anatomical structure of the operation area is complex, but it has a great impact on the postoperative effect. We measure the anatomical parameters of the stapes and its surrounding structures to provide an anatomical reference for stapes surgery in otosclerosis. Fifteen adult cadaver heads (30 samples) were scanned using micro-CT. The stapes, facial nerve and external auditory canal were reconstructed by image processing. The stapes parameters and relationships between the stapes and surrounding structures were measured using a three-dimensional reconstruction model. The length, width and thickness of the stapes footplate were 2.93 ± 0.17 mm, 1.46 ± 0.08 mm and 0.30 ± 0.11 mm, respectively. The distance between the stapes footplate and long process of the incus was 3.79±0.39 mm. The angle of the incudostapedial joint was 88.29 ± 11.58°. The distance from the center of the stapes footplate to the facial canal was 1.60 ± 0.34 mm. In simulated stapes surgery, the minimum depth of the external auditory canal to be removed was 2.17 ± 0.91 mm, and no significant difference was found between the left and right sides and between men and women (P > 0.05). A three-dimensional model of the stapes bone and its surrounding anatomical structures was established based on Micro-CT imaging. Anatomical parameters of the stapes bone and its surrounding structures were measured using the model. In stapedotomy, the implanted piston diameter should be around 0.6mm, with a length of approximately 4.6mm. Care should be taken to protect the facial nerve canal during the surgery. These data provide reference for otologists.

High-Resolution Computed Tomography of the Temporal Bone in Chronic Otitis Media: An Observational Study at a Tertiary Care Center in Jharkhand, India.

Chronic otitis media refers to middle ear inflammation. A radiological exam is a crucial step in this diagnostic process, in addition to a clinical evaluation and an evaluation by an audiologist. For the development of innovative surgical treatment plans for middle ear otitis media with the aim of minimally invasive surgery, accurate information regarding the extent of lesions is required. This is made possible by a temporal bone imaging test. The study was conducted at the Rajendra Institute of Medical Sciences (RIMS), a tertiary care facility in Ranchi, Jharkhand, India. The research was conducted between June 1, 2021, and October 31, 2022. In this prospective observational study, 50 patients who visited the otorhinolaryngology clinic at RIMS Ranchi were the participants. The median age was 26 years, there was a male-to-female ratio of 1.63 to 1, and the vast majority (84%) were from lower socioeconomic classes. High-resolution computed tomography has been shown to be highlysensitive and specific in identifying conditions including scutum erosion, malleus erosion, pneumatization type, mastoiditis, mastoid abscess, and morphological abnormalities such as low-lying dura. The semicircular canal, fallopian canal, dural plate, and sigmoid sinus may all be clearly defined by non-contrast computed tomography of the temporal bone in erosion in cases of otitis media.

Comparison of Endoplasmic Reticulum Stress Messenger Ribonucleic Acid Expression Between Chronic Otitis Media With and Without Cholesteatoma.

We evaluated and compared the role of endoplasmic reticulum stress in chronic otitis media with cholesteatoma and chronic otitis media without cholesteatoma. The messenger ribonucleic acid expression of endoplasmic reticulum stress was measured and compared between chronic otitis media with cholesteatoma and chronic otitis media without cholesteatoma according to the presence or absence of bacteria, type of hearing loss, ossicle destruction, and facial canal dehiscence. The expression of immunoglobulin heavy chain-binding protein messenger ribonucleic acid was higher in the chronic otitis media without cholesteatoma group than in the chronic otitis media with cholesteatoma group, and Protein kinase RNA (PKR)-like endoplasmic reticulum kinase and activating transcription factor 6 messenger ribonucleic acid expression were higher in the chronic otitis media with cholesteatoma group than in the chronic otitis media without cholesteatoma group. Endoplasmic reticulum stress messenger ribonucleic acids were expressed in both chronic otitis media with cholesteatoma and chronic otitis media without cholesteatoma. The levels of expression of endoplasmic reticulum stress messenger ribonucleic acids differed according to clinical features, suggesting that different endoplasmic reticulum stress pathways are involved in the pathophysiology of different types of chronic otitis media.

Accuracy of High-Resolution Computed Tomography Compared to High-Definition Ear Endoscopy to Assess Cholesteatoma Extension.

To correlate radiographic evidence of cholesteatoma in the retrotympanum with intraoperative endoscopic findings in cholesteatoma patients and to evaluate the clinical relevance of radiographic evidence of cholesteatoma in the retrotympanum. Case series with chart review. Tertiary referral center. Seventy-six consecutive cases undergoing surgical cholesteatoma removal with preoperative high-resolution computed tomography (HRCT) were enrolled in this study. A retrospective analysis of the medical records was conducted. The extension of cholesteatoma regarding different middle ear subspaces, into the antrum and mastoid were reviewed radiologically in preoperative HRCT and endoscopically from surgical videos. Additionally, facial nerve canal dehiscence, infiltration of the middle cranial fossa, and inner ear involvement were documented. Comparison of radiological and endoscopic cholesteatoma extension revealed statistically highly significant overestimation of radiological cholesteatoma extension for all retrotympanic regions (sinus tympani 61.8% vs19.7%, facial recess 69.7% vs43.4%, subtympanic sinus 59.2% vs7.9%, and posterior sinus 72.4% vs4.0%) and statistically significant overestimation for mesotympanum (82.9% vs56.6%), hypotympanum (39.5% vs9.2%), and protympanum (23.7% vs6.6%). No statistically significant differences were found for epitympanum (98.7% vs90.8%), antrum (64.5% vs52.6%), and mastoid (26.3% vs32.9%). Statistically significant radiological overestimation of facial nerve canal dehiscence (54.0% vs25.0%) and invasion of tegmen tympani (39.5% vs19.7%) is reported. Radiologic cholesteatoma extension in different middle ear subspaces is overestimated compared to the intraoperative extension. The preoperative relevance of radiological retrotympanic extension might be limited in the choice of approach and transcanal endoscopic approach is always recommended first.

The Compatibility of Preoperative Temporal Bone CT Scan Interpretation and Intraoperative Findings in Chronic Suppurative Otitis Media at Dr. Zainoel Abidin Hospital Banda Aceh

Introduction: Chronic suppurative otitis media (CSOM) is middle ear and mastoid infection that causes hearing loss globally. Computed Tomography (CT)-Scan of the temporal bone is useful for assessing the pathogenesis of the disease and estimating the prognosis. In addition, evaluation of CT-Scan in patients with CSOM is useful for selecting the appropriate surgical procedure to minimize post-surgical complications. This study aims to assess the suitability of temporal CT-Scan interpretation to intraoperatif findings in CSOM patients. Methods: This is an observational study with cross-sectional design conducted at the dr. Zainoel Abidin General Hospital, Banda Aceh. The components of suitability evaluation include cholesteatoma, scutum erosion, ossicles, tegmen tympani, facial canal, posterior wall and sigmoid sinus wall. The interpretation suitability of temporal CT-Scan and intraoperatif findings was performed using the Kappa test. Results: A total of 18 CSOM patients were involved in this study with a mean age of 32.44 years and dominated by the safe type with a percentage of 55.6%. Interpretation of ossicular erosion based on temporal CT scan has very strong suitability with the intraoperatif findings with k=0.88 followed by posterior wall erosion (k=0.684), scutum erosion (k=0.679), tympanic tegmen erosion (k=0.455) and facial canal erosion (k=0.341). The findings of cholesteatoma and erosion of the sigmoid sinus wall had a very low suitability (k&lt;0.001). Conclusion: Temporal CT scan in CSOM patients has relatively good suitability with intraoperatif findings in evaluating erosion of the ossicles, posterior wall, and scutum. Another examination modality is necessary to assess and improve the accuracy of disease pathogenesis.

Transmastoid/Infralabyrinthine Approach to the Jugular Foramen: 2-Dimensional Operative Video.

This approach is intended for tumors centered in the jugular foramen with extensions between intracranial and extracranial spaces, possible spread to the middle ear, and variable bony destruction. 1,2. Jugular foramen paragangliomas are complex lesions that usually invade and fill related venous structures. They present complex relationships with skull base neurovascular structures as internal carotid artery, lower cranial nerves (CNs), middle ear, and mastoid segment of facial nerve. In this way, it is essential to perform an adequate preoperative vascular study to evaluate sinus patency and the tumor blood supply, besides a computed tomography scan to depict bone erosion. Mastoidectomy through an infralabyrinthine route up to open the lateral border of jugular foramen, allowing exposure from the sigmoid sinus to internal jugular vein. Skeletonization of facial canal without exposure of facial nerve is performed and opening of facial recess to give access to the middle ear in way of a fallopian bridge technique. 2-10. If there is preoperative preservation of lower CN function, it is important to not remove the anteromedial wall of the internal jugular vein and jugular bulb. In addition, facial nerve should be exposed just in case of preoperative facial palsy to decompress or reconstruct the nerve. Variations are related mainly with temporal bone drilling depending on the extensions of the lesion, its source of blood supply, and preoperative preservation of CN function.Informed consent was obtained from the patient for the procedure and publication of his image.Anatomy images were used with permission from:• Ceccato GHW, Candido DNC, and Borba LAB. Infratemporal fossa approach to the jugular foramen. In: Borba LAB and de Oliveira JG. Microsurgical and Endoscopic Approaches to the Skull Base. Thieme Medical Publishers. 2021.• Ceccato GHW, Candido DNC, de Oliveira JG, and Borba LAB. Microsurgical Anatomy of the Jugular Foramen. In: Borba LAB and de Oliveira JG. Microsurgical and Endoscopic Approaches to the Skull Base. Thieme Medical Publishers. 2021.

Fallopian Canal Meningocele Causing Cerebrospinal Fluid Rhinorrhoea

Fallopian canal meningocele is an extremely rare cause of cerebrospinal fluid rhinorrhoea. Also, due to complex anatomical relations and a lack of experience, its management remains a challenge. Here we report a case focusing on its clinical course, radiological features, and management.

Simplified Easy-Accessible Smartphone-Based Photogrammetry for 3-Dimensional Anatomy Presentation Exemplified With a Photorealistic Cadaver-Based Model of the Intracranial and Extracranial Course of the Facial Nerve.

Smartphone-based photogrammetry (SMPhP) was recently presented as a practical and simple algorithm to create photorealistic 3-dimensional (3D) models that benefit from volumetric presentation of real anatomic dissections. Subsequently, there is a need to adapt the techniques for realistic depiction of layered anatomic structures, such as the course of cranial nerves and deep intracranial structures; the feasibility must be tested empirically. This study sought to adapt and test the technique for visualization of the combined intracranial and extracranial course of the facial nerve's complex anatomy and analyze feasibility and limitations. We dissected 1 latex-injected cadaver head to depict the facial nerve from the meatal to the extracranial portion. A smartphone camera alone was used to photograph the specimen, and dynamic lighting was applied to improve presentation of deep anatomic structures. Three-dimensional models were created with a cloud-based photogrammetry application. Four 3D models were generated. Two models showed the extracranial portions of the facial nerve before and after removal of the parotid gland; 1 model showed the facial nerve in the fallopian canal after mastoidectomy, and 1 model showed the intratemporal segments. Relevant anatomic structures were annotated through a web-viewer platform. The photographic quality of the 3D models provided sufficient resolution for imaging of the extracranial and mastoid portions of the facial nerve, whereas imaging of the meatal segment only lacked sufficient precision and resolution. A simple and accessible SMPhP algorithm allows 3D visualization of complex intracranial and extracranial neuroanatomy with sufficient detail to realistically depict superficial and deeper anatomic structures.

Facial canal dehiscence in cholesteatoma and co-existing surgical findings: a systematic review and meta-analysis

Facial canal dehiscence in cholesteatoma and co-existing surgical findings: a systematic review and meta-analysis

Clinical and Surgical Features of Acquired Middle Ear Cholesteatoma: A 10 Years Population-Based Study

Background: Cholesteatomas are benign destructive lesions of the temporal bone that may lead to life-threatening complications. Objectives: This study described the clinical and surgical characteristics of chronic otitis media patients with acquired middle ear cholesteatoma. Methods: Among 1790 patients with chronic otitis media detected during almost 10 years, 449 suffered from cholesteatoma. The clinical features and surgical data were investigated. Results: Among the chronic otitis media patients, 449 (25.0%) cases had cholesteatoma with a mean age of 32.2 ± 16.1 SD years, and 62.8% were male. The most common symptom was otorrhea (53%), followed by hearing impairment (37.9%). Erosion of the facial nerve canal was observed in 33.1% of patients, dural plate erosion in 4.8% of cases, and labyrinthine fistula in 10.3% of patients. Moreover, ossicular chain erosion was observed with the highest frequency in incus (40%), followed by malleus (33%) and stapes (26%). Amongst the surgically treated patients, 59.3% underwent mastoidectomy with canal wall preservation, 29.7% underwent modified radical mastoidectomy, and radical mastoidectomy was performed in 11% of patients. Conclusions: Cholesteatoma was seen in about a quarter of patients with chronic otitis media. Based on our findings, cholesteatoma can be associated with serious complications such as facial nerve canal erosion (33.1%), dural plate erosion (4.8%), and labyrinthine fistula (10.3%). Regarding the functional importance of the hearing system and the high prevalence of disease complications, middle ear cholesteatoma needs long-term follow-up.

Comparison of Preop High Resolution CT Temporal Bone Findings with Intraoperative Findings in Cholesteatoma

Background: Since many years, CT-scan of the temporal bone is a widely accepted investigation in preoperative evaluation of patients with cholesteatoma in the middle ear. Aim: To compare the preoperative HRCT findings with intraoperative findings in the patients with atticoantral CSOM Study design: Comparative cross-sectional study Setting: Department of ENT Sir Ganga Ram Hospital Lahore Duration: February 1st 2022 to January 31st 2023 Methods: After taking approval from board of studies, IRB &amp; ASRB of FJMU, 50 patients fulfilling inclusion criteria were admitted in Department of ENT, Sir Ganga Ram Hospital Lahore. Firstly patients were seen in outdoor, history and otoscopy followed by examination under microscope was done, then the diagnosis of atticoantral CSOM was established. HRCT temporal bone of the cases diagnosed as atticoantral type CSOM was done. The patients were then admitted for mastoid exploration. Informed consent was obtained. Demographic information was recorded. HRCT temporal bone was reported by consultant radiologist from Department of Radiology, Sir Ganga Ram Hospital in all cases. Intraoperative findings like soft tissue mass, dural&amp; sinus plate, ossicular status, status of semicircular canal, facial canal and scutum was noted and compared with the preoperative HRCT findings. Then the data was collected in accordance to patients Proforma. Results: The mean age of patients was 22.32±10.42 years. Among patients 56% were male and 44% were female. HRCT was closely in agreement with intraoperative findings for detection of soft tissues mass in middle ear [HRCT:92% &amp; IOF: 100%], dural plates [HRCT:98% &amp; IOF: 98%], Sigmoid sinus plates [HRCT:92% &amp; IOF: 92%], erosion of malleus [HRCT:56% &amp; IOF: 62%], Incus [HRCT:56% &amp; IOF: 26%], stapes [HRCT:60% &amp; IOF: 66%], ;lateral semicircular canal [HRCT:96% &amp; IOF:96%], facial canal nerve [HRCT:96% &amp; IOF: 94%] and scutum [HRCT:70% &amp; IOF: 74%] respectively. This would be of great help to the otologists in anticipating the possible complications, developing treatment strategy, counseling the patient regarding the procedure and in taking consent about expected complications. Conclusion: In patients of atticoantral CSOM HRCT effectively helps in preoperative assessment of the site &amp; extent of the disease process, Ossicular erosion and status of various important anatomical structure. Keywords: Preoperative, HRCT, Intraoperative, Atticoantral, CSOM, Mastoidectomy, Ossicular necrosis.

Intratemporal facial nerve neurofibroma: a case report and review of literature

Facial nerve neurofibromas (FNN) are a rare benign tumor of facial nerve can arise from anywhere along the course of the facial nerve from the cerebellopontine angle (CPA) to the extracranial branches within the parotid. They are most commonly located in the parotid gland, and FNN in temporal bone are rarely reported. Intratemporal facial neurofibroma arise from facial nerve in internal auditory canal or in Fallopian canal. It usually manifests as progressive facial palsy, but also can present as sudden or repetitive facial palsy mimicking Bell’s palsy. We reported a case of intratemporal facial neurofibroma arising mainly from mastoid segment in 17-year-old female who presented with progressive facial palsy for 3 years. We briefly reviewed previous cases of intratemporal facial neurofibroma reported in the literature to provide a comprehensive understanding of this rare entity.

Diagnosis and treatment of the otitis externa and media

Diagnosis and treatment of the otitis externa and media

Transcranial Magnetic Stimulation in the Differential Diagnosis of Unilateral Peripheral Facial Nerve Palsy

(1) Background: This study aims to assess the diagnostic accuracy of parameters based on a combination of transcranial magnetic stimulation (TMS) and electrical stimulation (ES) in the differentiation between idiopathic and secondary facial palsy in a large cohort of patients. (2) Methods: Patients with unilateral facial palsy ≤7 days after symptom onset were included. Compound muscle action potential (CMAP) amplitudes were measured after stimulation of both facial nerves at (A) the internal acoustic meatus using TMS, CMAP-TMS, and (B) at the stylomastoid foramen using electrical stimulation, CMAP-ES. To express the degree of nerve dysfunction in the facial canal specifically, the amplitude reduction of the CMAP-TMS in relation to CMAP-ES was calculated and expressed as a percentage (amplitude reduction over the facial canal, ARFC). Receiver Operating Characteristic (ROC) curves were constructed to assess the diagnostic accuracy of ARFC as a marker to discriminate between patients with idiopathic and secondary facial palsy. (3) Results: Data from 498 patient records were analyzed. Idiopathic facial palsy was diagnosed in 424 patients, and secondary facial palsy in 74 patients. The area under the ROC curve for ARFC was 0.398. (4) Conclusions: The overall diagnostic accuracy of this method to differentiate secondary from idiopathic facial palsy is low.

A New Specimen of cf. Isanacetus laticephalus (Baleen Whale) from the Oi Formation, Ichishi Group (Late Early Miocene) in Japan

In the history of baleen whales, the early Miocene is one of not a well-known time. Many baleen whales from the Miocene are known as “cetotheres”. The “cetothere” Isanacetus laticephalus was a baleen whale from the early to middle Miocene that is only known from Japan. The holotype and paratype of I. laticephalus are well-preserved, and the age of the species I. laticephalus makes it one of the earlier basal plicogulans; however, its phylogenetic position is unclear. Here, a new cranium including the periotic from an early Miocene deposit (about 18.5 to 17.0 Ma) of the Oi Formation, Ichishi Group in Mie, Japan is reported as cf. I. laticephalus. The specimen displays a combination of four periotic features: (i) a large lateral tuberosity; (ii) a rectangular pars cochlearis; (iii) a robust neck of the posterior process, and (iv) a cerebral aperture of the facial canal that is smaller than that of the dorsal vestibular area. This combination of features could be diagnostic for I. laticephalus, among basal plicogulans from the early and middle Miocene. Adding more referred specimens will expand the diagnoses of I. laticephalus, and firmly support phylogenetic trees with this species.