-
Journal of Neurosurgery Nov 2022The petrosal process of the sphenoid bone (PPsb) is a relevant skull base osseous prominence present bilaterally that can be used as a key surgical landmark, especially...
OBJECTIVE
The petrosal process of the sphenoid bone (PPsb) is a relevant skull base osseous prominence present bilaterally that can be used as a key surgical landmark, especially for identifying the abducens nerve. The authors investigated the surgical anatomy of the PPsb, its relationship with adjacent neurovascular structures, and its practical application in endoscopic endonasal surgery.
METHODS
Twenty-one dried skulls were used to analyze the osseous anatomy of the PPsb. A total of 16 fixed silicone-injected postmortem heads were used to expose the PPsb through both endonasal and transcranial approaches. Dimensions and distances of the PPsb from the foramen lacerum (inferiorly) and top of the posterior clinoid process (PCP; superiorly) were measured. Moreover, anatomical variations and the relationship of the PPsb with the surrounding crucial structures were recorded. Three representative cases were selected to illustrate the clinical applications of the findings.
RESULTS
The PPsb presented as a triangular bony prominence, with its base medially adjacent to the dorsum sellae and its apex pointing posterolaterally toward the petrous apex. The mean width of the PPsb was 3.5 ± 1 mm, and the mean distances from the PPsb to the foramen lacerum and the PCP were 5 ± 1 and 11 ± 2.5 mm, respectively. The PPsb is anterior to the petroclival venous confluence, superomedial to the inferior petrosal sinus, and inferomedial to the superior petrosal sinus; constitutes the inferomedial limit of the cavernous sinus; and delimits the upper limit of the paraclival internal carotid artery (ICA) before the artery enters the cavernous sinus. The PPsb is anterior and medial to and below the sixth cranial nerve, forming the floor of Dorello's canal. During surgery, gentle mobilization of the paraclival ICA reveals the petrosal process, serving as an accurate landmark for the location of the abducens nerve.
CONCLUSIONS
This investigation revealed details of the microsurgical anatomy of the PPsb, its anatomical relationships, and its application as a surgical landmark for identifying the abducens nerve. This novel landmark may help in minimizing the risk of abducens nerve injury during transclival approaches, which extend laterally toward the petrous apex and cavernous sinus region.
PubMed: 35276642
DOI: 10.3171/2021.12.JNS212024 -
Graefe's Archive For Clinical and... Jan 2021To investigate the relationship between ocular motility and lateral rectus (LR) muscle volume according to the presence or absence of the abducens nerve in patients with...
PURPOSE
To investigate the relationship between ocular motility and lateral rectus (LR) muscle volume according to the presence or absence of the abducens nerve in patients with Duane's retraction syndrome (DRS) using high-resolution magnetic resonance imaging (MRI).
METHODS
A total of 54 unilateral DRS patients were divided into two groups according to high-resolution MRI findings: DRS without an abducens nerve on the affected side (absent CN6 group, n = 45) and DRS with symmetric abducens nerves on both sides (present CN6 group, n = 9). Ocular motility was measured by image analysis based on nine gaze photographs. LR volume was measured on T2-weighted coronal MRI of the orbit, and the ratio of paretic/normal side (P/N) LR volume was investigated. Association of the abducens nerve with various parameters including ocular motility, LR volume, and ratios of P/N LR volume were determined.
RESULTS
LR volume was smaller in the affected eye than the non-affected eye in both groups. In the present CN6 group, abducens nerve diameter and the ratio of P/N LR volume showed a positive correlation. A smaller LR volume and more limitation of abduction in the affected eye were predictive of an absent abducens nerve in DRS.
CONCLUSIONS
LR muscle hypoplasia was apparent in the affected eye of DRS patients. Abducens nerve diameter positively correlated with the ratio of P/N LR volume in the present CN6 group. Graphical abstract.
Topics: Abducens Nerve; Abducens Nerve Diseases; Duane Retraction Syndrome; Eye Movements; Humans; Oculomotor Muscles
PubMed: 32820345
DOI: 10.1007/s00417-020-04845-y -
World Neurosurgery Feb 2022Metastatic lesions of the clivus are extremely rare, having previously been estimated as representing 0.02% of all intracranial tumors. Owing to its close intracranial... (Review)
Review
BACKGROUND
Metastatic lesions of the clivus are extremely rare, having previously been estimated as representing 0.02% of all intracranial tumors. Owing to its close intracranial relationship with the clivus before entering the cavernous sinus, clinical palsies of the sixth cranial nerve have been classically associated with destructive lesions of this structure.
METHODS
A comprehensive search of PubMed was conducted for studies of patients with metastasis to the clivus from primary cancer at any site. Studies reported in English in the past 20 years from our last search on April 12, 2021 were included. The data collected included patient age, sex, symptoms at presentation, histopathology and treatment timeline of the primary tumor, treatment, follow-up, and mortality.
RESULTS
After the literature review, 46 studies reporting on 58 patients with clivus metastasis were included in the final analysis. The mean age of the patients was 57.5 years, and 39 were male (67.2%). The most common sites of the primary tumor were the prostate (22%), gastrointestinal tract (15%), lung (13%), and kidney (11%). In 43% of patients, symptoms of clivus metastasis had presented before the diagnosis of primary cancer was known, and 71% of the patients had presented with sixth nerve palsy. Of the 58 patients, 53% had undergone surgery, and 37% had received adjuvant radiotherapy. Of the 58 patients, 25% had received radiotherapy alone. The endoscopic transsphenoidal approach to the clivus was almost uniquely used for surgical management. Survival data were available for 31 patients. Death had occurred at a mean of 9.4 months after the presentation of clivus metastasis. A strong correlation was found between the interval from primary cancer to the presentation of clivus metastasis and mortality.
CONCLUSIONS
Although an extremely rare occurrence, clivus metastasis should be considered in patients with a history of malignancy, in particular, prostate malignancy, presenting with new-onset isolated sixth nerve palsy.
Topics: Abducens Nerve Diseases; Cavernous Sinus; Cranial Fossa, Posterior; Endoscopy; Female; Humans; Male; Middle Aged; Skull Base Neoplasms
PubMed: 34861450
DOI: 10.1016/j.wneu.2021.11.105 -
Romanian Journal of Ophthalmology 2022A 36-year-old female patient presented to our clinic with a two months history of diplopia and dizziness. The symptoms appeared gradually and increased in frequency and...
A 36-year-old female patient presented to our clinic with a two months history of diplopia and dizziness. The symptoms appeared gradually and increased in frequency and intensity. She had no significant medical history and she did not take any medication. A full ophthalmological consult was performed, which revealed restricted ocular motility in the left eye (LE), in left gaze. Otherwise, the examination showed no pathological findings: best corrected visual acuity (BCVA) both eyes (OU) 1 (Snellen chart), normal slit lamp examination and pupillary reflexes, normal intraocular pressure (IOP) and fundus aspect. Diplopia tests revealed a horizontal diplopia, exacerbated in left gaze. Sixth nerve palsy suspicion was raised and the patient was directed to the neurology department. Following magnetic resonance imaging, with angiographic sequence, a complex intracerebral vascular malformation that interacted with the cranial nerves and determined horizontal diplopia, was found. For a correct diagnosis, we needed a good collaboration between various medical specialties, especially ophthalmology and neurology, because patients with diplopia often present for the first time at the ophthalmologist. BCVA = best corrected visual acuity, IOP = intraocular pressure, LE = left eye, RE = right eye.
Topics: Abducens Nerve Diseases; Adult; Diplopia; Female; Humans; Intraocular Pressure; Tonometry, Ocular; Visual Acuity
PubMed: 35531446
DOI: 10.22336/rjo.2022.15 -
Journal of Pediatric Ophthalmology and... 2021
Topics: Abducens Nerve; Abducens Nerve Diseases; Cadaver; Humans
PubMed: 34038276
DOI: 10.3928/01913913-20210209-01 -
Journal of AAPOS : the Official... Apr 2024To investigate the prevalence and risk of new-onset abducens nerve palsy and acute-onset diplopia following mRNA COVID-19 vaccination.
PURPOSE
To investigate the prevalence and risk of new-onset abducens nerve palsy and acute-onset diplopia following mRNA COVID-19 vaccination.
METHODS
In this retrospective, population-based study, patient data from the COVID-19 Research Network of TriNetX was searched via the TriNetX Analytics platform for patients who received specific vaccinations based on Common Procedural Technology codes. We recorded instances of newly diagnosed abducens nerve palsy and diplopia within 21 days following each vaccination event.
RESULTS
Of the 3,545,224 patients (mean age at vaccination, 46.2 ± 21.3 years) who received the mRNA COVID-19 vaccine, 12 (<0.0001%) patients had a new diagnosis of abducens nerve palsy and 453 (0.013%) had acute-onset diplopia within 21 days of first dose of COVID-19 vaccination. After propensity score matching, the relative risk for new abducens nerve palsy diagnosis after the first dose of COVID-19 vaccination was not significantly different from that after influenza (RR, 0.77), Tdap (RR, 1.0), or the second dose of the COVID-19 vaccinations (RR, 1.00). Furthermore, there was a lower risk of abducens nerve palsy diagnosis after the first dose of the COVID-19 vaccination compared with the risk after COVID-19 infection (RR, 0.15).
CONCLUSIONS
The risk of a new abducens nerve palsy diagnosis following the first dose of the COVID-19 vaccine is lower than the risk associated with COVID-19 infection itself. There is no evidence to suggest a causal relationship between COVID-19 vaccination and the development of abducens nerve palsy.
Topics: Humans; Abducens Nerve Diseases; COVID-19; COVID-19 Vaccines; Diplopia; Retrospective Studies; Vaccination
PubMed: 38458601
DOI: 10.1016/j.jaapos.2024.103867 -
Clinical & Experimental Optometry May 2022
Topics: Abducens Nerve; Humans; Paresis; Pons
PubMed: 34151746
DOI: 10.1080/08164622.2021.1924630 -
Italian Journal of Pediatrics Jun 2022Coronavirus disease 2019 (COVID-19) is a disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. Although many reports have detailed a...
BACKGROUND
Coronavirus disease 2019 (COVID-19) is a disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. Although many reports have detailed a range of neurological symptoms in SARS-CoV-2-infected patients, studies of neuro-ophthalmological manifestations are still scarce.
CASE PRESENTATION
We report a 9-year-old girl with abducens nerve palsy after COVID-19 with no evidence of other neurological disease on neuroimaging. At 2-month follow-up clinical conditions were improved.
CONCLUSIONS
The palsy may have occurred due to a possible post-infectious immune-mediated mechanism underlying the neuropathy, as opposed to direct viral infiltration. Despite being rare, this complication must be taken into account.
Topics: Abducens Nerve Diseases; COVID-19; Child; Female; Humans; Nervous System Diseases; SARS-CoV-2
PubMed: 35717391
DOI: 10.1186/s13052-022-01298-3 -
Current Oncology (Toronto, Ont.) Jul 2022Abducens nerve palsy is a severe dysfunction after petroclival meningioma (PC MNG) surgery. The objective of this investigation was to analyze abducens nerve outcomes in...
Abducens nerve palsy is a severe dysfunction after petroclival meningioma (PC MNG) surgery. The objective of this investigation was to analyze abducens nerve outcomes in patients who underwent the retrosigmoid approach in relation to the MIB-1 index. Thirty-two patients with primary sporadic PC MNG were retrospectively analyzed. Mean follow-up was 28.0 months. Analysis of the MIB-1 index was performed to evaluate the abducens nerve outcome. An optimal MIB-1 index cut-off value (<4/≥4) in the association with postoperative CN VI palsy was determined by ROC analysis (AUC: 0.74, 95% CI: 0.57−0.92). A new-onset CN VI palsy was present in 7 cases (21.88%) and was significantly associated with an increased MIB-1 index (≥4%, p = 0.025) and a peritumoral edema in the brachium pontis (p = 0.047) which might be caused by the increased growth rate. Tumor volume, cavernous sinus infiltration, auditory canal invasion, and Simpson grading were not associated with new CN VI deficits. Six (85.7%) of the 7 patients with both an increased MIB-1 index (≥4%) and new abducens nerve palsy still had a CN VI deficit at the 12-month follow-up. A peritumoral edema caused by a highly proliferative PC MNG with an elevated MIB-1 index (≥4%) is associated with postoperative abducens nerve deficits.
Topics: Abducens Nerve; Abducens Nerve Diseases; Humans; Meningeal Neoplasms; Meningioma; Morbidity; Paralysis; Retrospective Studies
PubMed: 35877258
DOI: 10.3390/curroncol29070398 -
Journal of Neurosurgery. Case Lessons May 2024Unilateral cranial nerve (CN) VI, or abducens nerve, palsy is rare in children and has not been reported in association with Chiari malformation type 1 (CM1) in the...
BACKGROUND
Unilateral cranial nerve (CN) VI, or abducens nerve, palsy is rare in children and has not been reported in association with Chiari malformation type 1 (CM1) in the absence of other classic CM1 symptoms.
OBSERVATIONS
A 3-year-old male presented with acute incomitant esotropia consistent with a unilateral, left CN VI palsy and no additional neurological symptoms. Imaging demonstrated CM1 without hydrocephalus or papilledema, as well as an anterior inferior cerebellar artery (AICA) vessel loop in the immediate vicinity of the left abducens nerve. Given the high risk of a skull base approach for direct microvascular decompression of the abducens nerve and the absence of other classic Chiari symptoms, the patient was initially observed. However, as his palsy progressed, he underwent posterior fossa decompression with duraplasty (PFDD), with the aim of restoring global cerebrospinal fluid dynamics and decreasing possible AICA compression of the left abducens nerve. Postoperatively, his symptoms completely resolved.
LESSONS
In this first reported case of CM1 presenting as a unilateral abducens palsy in a young child, possibly caused by neurovascular compression, the patient's symptoms resolved after indirect surgical decompression via PFDD.
PubMed: 38710112
DOI: 10.3171/CASE23539