The arcuate eminence (AE) is an anatomically consistent bony protrusion located on the upper surface of the petrous bone that has been previously studied as a reference for lateral skull base approaches. There is a paucity of information in the neurosurgical literature seeking to improve the safety of the extended middle cranial fossa (MCF) approach using detailed morphometric analysis of the AE.
To evaluate the use of the AE as an anatomical landmark to help with early identification of the internal acoustic canal (IAC) in MCF approaches by means of a cadaveric study, using a new morphometric reference termed the \"M-point.\"
A total of 40 dry temporal bones and 2 formalin-preserved, latex-injected cadaveric heads were used. The M-point was established as a new anatomic reference by identifying the intersection of a line perpendicular to the alignment of the petrous ridge (PR), originating from the midpoint of the AE, with the PR itself. Subsequent anatomical measurements were performed to measure the distance between M-point and IAC. Additional distances, including PR length and the anteroposterior and lateral AE surfaces, were also measured.
The mean distance between the M-point and the center of the IAC was 14.9 mm (SD ± 2.09), offering a safe drilling area during an MCF approach.
This study provides novel information on identification of a new anatomic reference point known as the M-point that that can be used to improve early surgical identification of the IAC.

To determine the anatomical characteristics of the petrous ridge and trigeminal nerve in trigeminal neuralgia (TN) without neurovascular compression (NVC).
From May 2017 to March 2021, 66 patients (49 female and 17 male; mean age ± standard deviation [SD], 56.8 ± 13.3 years) with TN without NVC and 57 controls (46 female and 11 male; 52.0 ± 15.6 years) were enrolled. The angle of the petrous ridge (APR) and angle of the trigeminal nerve (ATN) were measured using magnetic resonance imaging with a high-resolution three-dimensional T2 sequence. Data on the symptomatic side were compared with those on the asymptomatic side in patients and with the mean measurements of the bilateral sides in controls. Receiver operating characteristic (ROC) analysis was conducted to evaluate the performance of APR and ATN in distinguishing TN patients from controls.
In TN patients without NVC, the mean ± standard deviation (SD) of APR on the symptomatic side (98.40° ± 19.75°) was significantly smaller than that of the asymptomatic side (105.59° ± 22.45°, p = 0.019) and controls (108.44° ± 15.98°, p = 0.003). The mean ATN ± SD on the symptomatic side (144.41° ± 8.92°) was significantly smaller than that of the asymptomatic side (149.67° ± 8.09°, p = 0.003) and controls (150.45° ± 8.48°, p = 0.001). The area under the ROC curve for distinguishing TN patients from controls was 0.673 (95% confidence interval [CI]: 0.579-0.758) for APR and 0.700 (CI: 0.607-0.782) for ATN. The sensitivity and specificity using the diagnostic cutoff yielding the highest Youden index were 81.8% (54/66) and 49.1% (28/57), respectively, for APR (with a cutoff score of 94.30°) and 65.2% (43/66) and 66.7% (38/57), respectively, for ATN (cutoff score, 148.25°).
In patients with TN without NVC, APR and ATN were smaller than those in controls, which may explain the potential cause of TN and provide additional information for diagnosis.

Dyke-Davidoff-Masson syndrome (DDMS) refers to atrophy or hypoplasia of one cerebral hemisphere, due to an insult to the developing brain in fetal or early childhood period. Age of presentation depends on the time of neurologic insult, and characteristic changes may be seen only in adolescence. Male gender and left hemisphere are more frequently involved. A 17-year-old female adolescent with a history of recurrent refractory seizures, hemiplegia and mental retardation reported to Department of Radiology for computed tomography (CT) assessment of brain. On examination, she had facial asymmetry, delayed milestones, and spastic hemiplegia. The CT brain showed right cortical atrophy with ventricular dilatation, prominent sulci, and shifting of falx to the right side. Bone window image showed asymmetry in skull vault thickness, the width of diploic space, the size of paranasal air sinuses and inclination of the petrous ridge between the affected and normal sides. As the above case deviates from the usual presentation of male left sided DDMS, hence the report.