Comments on the pelvic girdle anatomy of Lagerpeton chanarensis Romer, 1971 (Archosauria) and its implications on the posture and gait of early pterosauromorphs

Lagerpeton chanarensis is an early avemetatarsalian from the lower Carnian (lowermost Upper Triassic) levels of the Chañares Formation, La Rioja Province, Argentina. Lagerpeton and its kin were traditionally interpreted as dinosaur precursors of cursorial habits, with a bipedal posture and parasagittal gait. Some authors also speculated saltatorial capabilities for this genus. Recent analyses indicate that lagerpetids are early-diverging pterosauromorphs, a hypothesis that invites a review of most aspects of their anatomy and function. A revision of available specimens and additional preparation of previously known individuals indicate that Lagerpeton lacked a parasagittal gait and was probably a sprawling archosaur. This latter inference is based on the femoral head articulation with the acetabulum. The acetabular rim has a strongly laterally projected posteroventral antitrochanteric corner, which results in a position of the legs that recalls that of sprawling living reptiles, such as lizards, and departs from the parasagittally positioned limbs of dinosaurs. This may indicate that early pterosauromorphs had a sprawling posture of their hindlegs, casting doubts on the significance of bipedal posture and parasagittal gait for the radiation of early ornithodirans, given that both traits have been regarded as key features that triggered the ecological and evolutionary success of the clade. Our results bolster recent claims of a high ecomorphological diversity among early avemetatarsalians.

[Comparison of methods of treatment of meningiomas invading the superior sagittal sinus]

There are various approaches to the treatment of patients with parasagittal meningiomas.

OBJECTIVE

To optimize treatment strategy for meningiomas invading the superior sagittal sinus.

MATERIAL AND METHODS

The study included 87 patients with benign parasagittal meningiomas between 2010 and 2012. Of these, 34 patients underwent surgery alone, 27 - radiotherapy, 26 - surgery and subsequent radiotherapy. Both groups were comparable in male-to-female ratio, age and localization of tumors in relation to superior sagittal sinus. The follow-up period was at least 5 years. We analyzed the effect of treatment on neurological status, Karnofsky score and tumor growth control.

RESULTS

Mean volume of tumors was 43.3 cm3 in patients undergoing surgery and 6.7 cm3 in the radiotherapy group. In the combined treatment group, mean volume was 65.8 cm3 before surgery and 8.8 cm3 before irradiation. General cerebral symptoms (84%), epileptic seizures (37%) and movement disorders (31%) prevailed. Surgery provided the best results in patients with small meningiomas (<14 cm3) causing focal neurological symptoms. Isolated radiotherapy was the most effective in asymptomatic patients. Large tumors required surgery with adjuvant irradiation.

CONCLUSION

Benign parasagittal meningiomas followed by focal neurological symptoms require surgical intervention regarding the best functional outcomes and tumor growth control. Radiotherapy without surgery is advisable for progressive asymptomatic tumors. Resection followed by irradiation is preferable if total resection without the risk of damage to veins and cortex is impossible.

Diagnostic utility of parasagittal measurements of tonsillar herniation in Chiari I malformation

BACKGROUND AND PURPOSE

Although the cerebellar tonsils are parasagittal structures, the extent of tonsillar herniation (ETH) in Chiari I malformation (CMI) is currently measured in the midsagittal plane. We measured the ETH of each cerebellar tonsil in the parasagittal plane and assessed their diagnostic utility by comparing them to the midsagittal ETH measurements in predicting cough-associated headache (CAH), an indicator of clinically significant disease in CMI.

METHODS

Eighty-five CMI patients with 3D-MPRAGE images were included. Neurosurgeons determined the presence of CAH. Sagittal images were used to measure ETH in the midsagittal (MS_ETH) and parasagittal planes (by locating tonsillar tips on each side on reformatted coronal images). Given the parasagittal ETH (PS_ETH) asymmetry in the majority of cases, they were considered Smaller_PS_ETH or Larger_PS_ETH. The accuracy of ETH measurements was assessed by the receiver operating characteristic (ROC) curve.

RESULTS

Of 85 patients, 46 reported CAH. ROC analysis showed an area under the curve (AUC) of 0.78 for Smaller_PS_ETH significantly better than 0.65 for MS-ETH in predicting CAH (p = 0.001). An AUC of 0.68 for Larger_PS_ETH was not significantly different from MS_ETH. The sensitivity and specificity of predicting CAH were 87% and 28% for MS_ETH >6 mm versus 90% and 46% for Smaller_PS_ETH >6 mm, and 52% and 67% for MS_ETH >9 mm versus 48% and 87% for Smaller_PS_ETH >9 mm. At ETH >15 mm, no differences were seen between the measurements.

CONCLUSIONS

Diagnostic utility of ETH measurements in detecting clinically significant CMI can be improved by parasagittal measurements of the cerebellar tonsillar herniation.

Interhemispheric Approach

The interhemispheric approach is the natural route to reach the parafalcine and paraventricular structures through the interhemispheric fissure. In this chapter, we report the main anterior and posterior corridors of the interhemispheric approach.

[Comprehensive treatment of patients with parasagittal meningiomas]

For many years, radical surgery was considered the only effective method for treating meningiomas, including parasagittal meningiomas (PSM). However, accumulated experience makes it evident that extensive resections in the parasagittal region lead to impaired venous outflow and involve high rates of disability and mortality. In recent decades, stereotactic radiotherapy has been developed and widely implemented in practical neurosurgery, its role in the treatment of PSM patients is discussed in this work.

MATERIAL AND METHODS

A sample of publications in the PubMed search system was taken using the following keywords: meningioma, parasagittal, superior sagittal sinus, stereotactic radiosurgery, stereotactic radiation therapy. No publications of evidence levels 1 and 2 have been found. Out of 123 works, 32 most relevant were selected.

RESULTS AND DISCUSSION

Currently, both neurosurgeons and radiologists are involved in the treatment of PSM. An analytical review of the literature on the treatment of PSM is presented. Both surgical treatment and radiation therapy have their pros and cons. No general approach to the treatment of these tumours has been developed to date. A comprehensive treatment is considered to be effective - the maximum possible removal of the tumor without damaging functionally significant structures, including venous outflow pathways, followed by radiotherapy for tumor residues.

CONCLUSION

In the existing literature, it was not possible to identify a single decision-making algorithm for the tactics of multimodality therapy for PSM patients, including the one for manipulations on the superior sagittal sinus and with regard to the role of ir irradiation radiation methods.

Reliability of transperineal ultrasound for the assessment of the angle of progression in labor using parasagittal approach versus midsagittal approach

OBJECTIVE

To assess the inter-method agreement between midsagittal (msAoP) and parasagittal (psAoP) measurements of the angle of progression (AoP) during labor. In addition, we aimed to evaluate the correlation between AoP measurements by both midsagittal and parasagittal approaches with the mode of delivery.

METHODS

We recruited a nonconsecutive series of women in active labor with a singleton uncomplicated term pregnancy with fetuses in vertex presentation. Women underwent transperineal ultrasound in the absence of uterine contractions or maternal pushing to measure both msAoP and psAoP. The inter-method agreement between the two acquisitions was then assessed. Lastly, both measurements were compared between women who had a vaginal delivery versus those who underwent cesarean section (CS).

RESULTS

Overall, 151 women were included in the study. We found an excellent agreement between msAoP and psAoP (ICC 0.935; 95% CI 0.912-0.953, p < .001). On the other hand, psAoP overestimated the measurements in comparison with msAoP (101.2 ± 15.6 versus 98.2 ± 16.0, p < .001). There was a significant correlation between both methods of AoP assessment and duration of the active second stage of labor and AoP measured by either method was significantly wider in patients who delivered vaginally compared to those who had a CS.

CONCLUSIONS

Our data showed a significant difference in the measured angle between the psAoP and the originally described msAoP. The automated measurements of AoP that have been introduced are designed using the parasagittal visualization of the more echogenic pubic arch, rather than the hypoechogenic pubic symphysis. We think that in the light of our data, care should be taken before applying data from midsagittal measurement in centers using the parasagittal automated approach.

Relationship between tumor location, size, and WHO grade in meningioma

OBJECTIVE Prior studies have investigated preoperative risk factors for meningioma; however, no association has been shown between meningioma tumor size and tumor grade. The objective of this study was to investigate the relationship between tumor size and grade in a large single-center study of patients undergoing meningioma resection. METHODS A retrospective chart review of patients undergoing meningioma resection at the University of California, San Francisco, between 1985 and 2015 was performed. Patients with incomplete information, spinal meningiomas, multiple meningiomas, or WHO grade III meningiomas were excluded. The largest tumor dimension was used as a surrogate for tumor size. Univariate and multivariate logistic regression models were used to investigate the relationship between tumor grade and tumor size. A recursive partitioning analysis was performed to identify groups at higher risk for atypical (WHO grade II) meningioma. RESULTS Of the 1113 patients identified, 905 (81%) had a WHO grade I tumor and in 208 (19%) the tumors were WHO grade II. The median largest tumor dimension was 3.6 cm (range 0.2-13 cm). Tumors were distributed as follows: skull base (n = 573, 51%), convexity/falx/parasagittal (n = 431, 39%), and other (n = 109, 10%). On univariate regression, larger tumor size (p < 0.001), convexity/falx/parasagittal location (p < 0.001), and male sex (p < 0.001) were significant predictors of WHO grade II pathology. After controlling for interactions, multivariate regression found male sex (OR 1.74, 95% CI 1.25-2.43), size 3-6 cm (OR 1.69, 95% CI 1.08-2.66), size > 6 cm (OR 3.01, 95% CI 1.53-5.94), and convexity/falx/parasagittal location (OR 1.83, 95% CI 1.19-2.82) to be significantly associated with WHO grade II. Recursive partitioning analysis identified male patients with tumors > 3 cm as a high-risk group (32%) for WHO grade II meningioma. CONCLUSIONS Larger tumor size is associated with a greater likelihood of a meningioma being WHO grade II, independent of tumor location and male sex, which are known risk factors.

Surgical outcomes after reoperation for recurrent non-skull base meningiomas

OBJECTIVE

Recurrent meningiomas are primarily managed with radiation therapy or repeat resection. Surgical morbidity after reoperation for recurrent meningiomas is poorly understood. Thus, the objective of this study was to report surgical outcomes after reoperation for recurrent non-skull base meningiomas.

METHODS

A retrospective review of patients was performed. Inclusion criteria were patients with recurrent meningioma who had prior resection and supratentorial non-skull base location. Univariate and multivariate logistic regression and recursive partitioning analysis were used to identify risk factors for surgical complications.

RESULTS

The authors identified 67 patients who underwent 111 reoperations for recurrent supratentorial non-skull base meningiomas. The median age was 53 years, 49% were female, and the median follow-up was 9.8 years. The most common presenting symptoms were headache, weakness, and seizure. The WHO grade after the last reoperation was grade I in 22% of cases, grade II in 51%, and grade III in 27%. The tumor grade increased at reoperation in 22% of cases. Tumors were located on the convexity (52%), parasagittal (33%), falx (31%), and multifocal (19%) locations. Tumors involved the middle third of the sagittal plane in 52% of cases. In the 111 reoperations, 48 complications occurred in 32 patients (48%). There were 26 (54%) complications requiring surgical intervention. There was no perioperative mortality. Complications included neurological deficits (14% total, 8% permanent), wound dehiscence/infection (14%), and CSF leak/pseudomeningocele/hydrocephalus (9%). Tumors that involved the middle third of the sagittal plane (OR 6.97, 95% CI 1.5-32.0, p = 0.006) and presentation with cognitive changes (OR 20.7, 95% CI 2.3-182.7, p = 0.001) were significantly associated with complication occurrence on multivariate analysis. The median survival after the first reoperation was 11.5 years, and the 2-, 5-, and 10-year Kaplan-Meier survival rates were 91.0%, 68.8%, and 50.0%, respectively.

CONCLUSIONS

Reoperation for recurrent supratentorial non-skull base meningioma is associated with a high rate of complications. Patients with cognitive changes and tumors that overlap the middle third of the sagittal plane are at increased risk of complications. Nevertheless, excellent long-term survival can be achieved without perioperative mortality.

Clinical features of central isolated unilateral foot drop: A case report and review of the literature

Background:

Intracranial cause of isolated unilateral foot drop is very rare. There may be a delay in the diagnosis of the cause of central foot drop or patients with such lesions might be misdiagnosed and subjected to unnecessary interventions. One of the reasons for the diagnostic uncertainty might be the absence of upper motor neuron (UMN) signs in the initial examination of such patients.

Case Description:

We present a very rare case of a 78-year-old woman who had presented with a five-year progressive right-sided unilateral isolated foot drop from a left-sided parasagittal tumor. Previously, she had undergone biopsy of an abnormality on the right C7/T1 facet, which was found to be benign. On examination of the patient, she had UMN signs in the ipsilateral foot. On magnetic resonance imaging scan of her head, a 3-cm left parasagittal lesion, consistent with it being a meningioma, was noted. The patient had significant medical history and declined to undergo surgical removal of the lesion.

Conclusion:

We review the literature on central foot drop from various intracranial pathologies and discern its clinical features. Patients with central foot drop often have UMN signs; however, these may be absent causing diagnostic uncertainty, and physicians should be vigilant of these variations in the presentation.