Radiography

Use of ‘Low-Risk Ankle Rule’ May Limit X-Rays in Children.

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Using the “low-risk ankle rule” to assess children’s ankle injuries in emergency departments significantly reduces X-ray imaging, according to aCanadian Medical Association Journal study.

Nearly 2200 patients aged 3 to 16 years presented with acute ankle injuries to emergency departments designated as either intervention or control sites. Intervention sites applied the rule, which says that radiography may not be necessary when tenderness and swelling is isolated to the distal fibula and the adjacent lateral ligaments distal to the tibial anterior joint line. At control sites, procedures for ankle injuries were unchanged.

After implementation of the rule, intervention sites saw a 22-percentage-point reduction in weekly ankle radiography, compared with controls. Application of the ankle rule was not associated with an increase in significant fractures being missed or a decrease in physician or patient satisfaction.

The authors conclude: “Widespread implementation of this rule could safely lead to reduction of unnecessary radiography in this radiosensitive population and a more efficient use of healthcare resources.”

Source: CMAJ

Chilaiditi’s sign.

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A 79-year-old man presented with symptoms and signs of upper respiratory tract infection; he had a history of permanent pacemaker implantation. An upright postero-anterior chest radiograph showed a raised right hemidiaphragm delineated by subdiaphragmatic air. Unlike free air, which forms an uninterrupted crescent-shaped subdiaphragmatic radiolucency, this radiograph showed a haustral pattern of subdiaphragmatic lucency, overlapping the upper border of the liver shadow. On examination, clinical findings suggesting acute abdomen from rupture of a hollow viscus were absent and there was no recent history of abdominal surgery to account for the presence of subdiaphragmatic air.

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The visualisation of a gas filled transverse colon lumen interpositioned between the right hemidiaphragm and the liver on a chest film is called Chilaiditi’s sign. A CT scan may confirm these anatomical relations. In our patient’s radiograph, the haustral pattern of air was indicative of colonic origin, and the continuity of the subdiaphragmatic air was broken up by the shadow of the vertical plicae semilunares of the colon. Chilaiditi’s sign was first described in 1910 by Demetrious Chilaiditi and it is an incidental radiographic finding. This sign can be mistaken for pneumoperitoneum and can lead to needless surgical intervention. Our patient was treated only for his upper respiratory tract infection.

Source: Lancet

Foramen ovale puncture, lesioning accuracy, and avoiding complications: microsurgical anatomy study with clinical implications.

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Abstract

OBJECT

Foramen ovale (FO) puncture allows for trigeminal neuralgia treatment, FO electrode placement, and selected biopsy studies. The goals of this study were to demonstrate the anatomical basis of complications related to FO puncture, and provide anatomical landmarks for improvement of safety, selective lesioning of the trigeminal nerve (TN), and optimal placement of electrodes.

METHODS

Both sides of 50 dry skulls were studied to obtain the distances from the FO to relevant cranial base references. A total of 36 sides from 18 formalin-fixed specimens were dissected for Meckel cave and TN measurements. The best radiographic projection for FO visualization was assessed in 40 skulls, and the optimal trajectory angles, insertion depths, and topographies of the lesions were evaluated in 17 specimens. In addition, the differences in postoperative pain relief after the radiofrequency procedure among different branches of the TN were statistically assessed in 49 patients to determine if there was any TN branch less efficiently targeted.

RESULTS

Most severe complications during FO puncture are related to incorrect needle placement intracranially or extracranially. The needle should be inserted 25 mm lateral to the oral commissure, forming an approximately 45° angle with the hard palate in the lateral radiographic view, directed 20° medially in the anteroposterior view. Once the needle reaches the FO, it can be advanced by 20 mm, on average, up to the petrous ridge. If the needle/radiofrequency electrode tip remains more than 18 mm away from the midline, injury to the cavernous carotid artery is minimized. Anatomically there is less potential for complications when the needle/radiofrequency electrode is advanced no more than 2 mm away from the clival line in the lateral view, when the needle pierces the medial part of the FO toward the medial part of the trigeminal impression in the petrous ridge, and no more than 4 mm in the lateral part. The 40°/45° inferior transfacial–20° oblique radiographic projection visualized 96.2% of the FOs in dry skulls, and the remainder were not visualized in any other projection of the radiograph. Patients with V1 involvement experienced postoperative pain more frequently than did patients with V2 or V3 involvement. Anatomical targeting of V1 in specimens was more efficiently achieved by inserting the needle in the medial third of the FO; for V2 targeting, in the middle of the FO; and for V3 targeting, in the lateral third of the FO.

CONCLUSIONS

Knowledge of the extracranial and intracranial anatomical relationships of the FO is essential to understanding and avoiding complications during FO puncture. These data suggest that better radiographic visualization of the FO can improve lesioning accuracy depending on the part of the FO to be punctured. The angles and safety distances obtained may help the neurosurgeon minimize complications during FO puncture and TN lesioning.

Source: JNS