CT and MR findings in neoplastic perineural spread along the vidian nerve

Diagnostic Accuracy of MRI in Detecting the Perineural Spread of Head and Neck Tumors: A Systematic Review and Meta-Analysis

The purpose of this study was to review the diagnostic accuracy of MRI in detecting perineural spreading (PNS) of head and neck tumors using histopathological or surgical evidence from the afflicted nerve as the reference standard. Previous studies in the English language published in the last 30 years were searched from PubMed and Embase databases. We included studies that used magnetic resonance imaging (MRI) (with and without contrast enhancement) to detect PNS, as well as the histological or surgical confirmation of PNS, and that reported the exact numbers of patients required for assessing diagnostic accuracy. The outcome measures were sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV). Heterogeneity was assessed with the Higgins inconsistency test (I2). P-values smaller than 0.05 were considered statistically significant. A total of 11 retrospective studies were found, reporting 319 nerve samples from 245 patients. Meta-analytic estimates and their 95% confidence intervals were as follows: sensitivity 0.85 (0.70-0.95), specificity 0.85 (0.80-0.89), PPV 0.86 (0.70-0.94), and NPV 0.85 (0.71-0.93). We found statistically significant heterogeneity for sensitivity (I2 = 72%, p = 0.003) and PPV (I2 = 70%, p = 0.038), but not for NPV (I2 = 65%, p = 0.119) or specificity (I2 = 12%, p = 0.842). The most frequent MRI features of PNS were nerve enlargement and enhancement. Squamous cell carcinoma and adenoid cystic carcinoma were the most common tumor types, and the facial and trigeminal nerves were the most commonly affected nerves in PNS. Only a few studies provided examples of false MRI diagnoses. MRI demonstrated high diagnostic accuracy in depicting PNS of cranial nerves, yet this statement was based on scarce and heterogeneous evidence.

Easily detected signs of perineural tumour spread in head and neck cancer

Abstract

Perineural tumour spread (PNTS) in head and neck oncology is most often caused by squamous cell carcinoma. The most frequently affected nerves are the trigeminal and facial nerves. Up to 40% of patients with PNTS may be asymptomatic. Therefore, the index of suspicion should be high when evaluating imaging studies of patients with head and neck cancer. This review describes a “quick search checklist” of easily detected imaging signs of PNTS.

Teaching Points

• A distinctive feature of head and neck tumours is growth along nerves.

• Perineural tumour spread is most often caused by squamous cell carcinoma.

• There are several key findings for the detection of perineural tumour spread.

Visualization of the vidian canal and nerve using magnetic resonance imaging

BACKGROUND AND PURPOSE

Few studies have investigated the vidian nerve (VN) and vidian canal (VC) with the use of magnetic resonance imaging (MRI). The present study aimed to characterize the VC and VN using MRI.

MATERIALS AND METHODS

A total of 91 patients underwent thin-sliced, contrast MRI. The course of the VC and VN and the relationships with relevant structures were analyzed.

RESULTS

The VC was identified in 95% of axial images on the right side and in 93% on the left. The course of the VC was delineated in 99% of serial coronal images on both sides. The VN location in the VC was highly variable. The course of the VC and transmitting VN was delineated in 95% of sagittal images on the right side and in 91% on the left. The mean length of the VC was 19.8 mm on the right side and 19.3 mm on the left. Topographical relationships between the anterior genu of the petrous internal carotid artery and the posterior end of the vidian canal could be classified into three types. Of these, the type terminating at the level of the petrous carotid was the most predominant, comprising 76% of 182 sides. The course of the VC and transmitting VN could be classified into four types. The straight type was the most predominant and was found in 41%.

CONCLUSIONS

The VC and transmitting VN are structures with variable morphologies. Contrast MRI is useful for delineating the VC and VN.

Location of Pterygopalatine Fossa and its Relationships to the Structures in Sellar Region

PURPOSE

The aim of this study is to locate pterygopalatine fossa (PPF) and the opening of its communicating canals by accessing the relationship between PFF and the endoscopic landmarks such as the tubercular recess (TR) and middle lowest point of sellar floor (SF) as well as analyze the relation between PPF and important structures such as internal carotid artery (ICA) and optic canal (OC).

MATERIALS AND METHODS

Computer topographic angiography (CTA) images of 118 PPF regions were reviewed. The measurement was on coronal, sagittal, and axial planes after multiplanar reconstruction (MPR). The location of PPF and its relationship to the sphenoid sinus, ICA, and OC were studied. The communicating canals of PPF, which were related to the transsphenoid approach, were three-dimensionally measured by the stationary structures, such as the middle lowest point of SF, the sagittal midline, and the top and bottom wall of sphenoid sinus.

RESULT

The posterior part of PPF was located by the middle lowest point of SF. The anterior opening of sphenopalatine foramen (SPF), pterygoid canal (PC), palatovaginal canal (PVC), and foramina rotundum (FR) have relative stationary position, which can be located by the landmarks of sellar region during the endoscopic surgery.

CONCLUSIONS

Pterygopalatine fossa is related to numerous neurovascular structures. Accurate understanding of the radiologic anatomy of PPF is beneficial for the PPF disease diagnosis, the selection of treatment plan and the prognosis evaluation.

Patterns of spread of head and neck adenoid cystic carcinoma

We present a review of head and neck adenoid cystic carcinoma (ACC). Imaging features of the primary tumour, patterns of locoregional spread, and distant metastasis with emphasis on perineural extension and imaging pitfalls are discussed with illustrated examples.

A Rare Finding of Schwannoma of the Vidian Canal: A Case Report

Background Schwannomas of the vidian canal are an extremely rare type of intracranial tumor that can have variable clinical presentations including headache, facial pain, facial muscle paralysis, decreased lacrimation, or nasal dryness. We present an atypical case of an incidentally identified asymptomatic vidian canal schwannoma.

Case Description A 49-year-old woman with a history of multiple sclerosis presented for routine surveillance magnetic resonance imaging that detected an ovoid mass originating in the vidian canal. Given the unusual location of the lesion, an endoscopic endonasal biopsy was performed and confirmed the diagnosis of a vidian canal schwannoma, for which the patient chose to receive fractionated radiation therapy.

Conclusion When a vidian canal tumor is identified, endoscopic endonasal biopsy can be used to confirm the diagnosis before pursuing either surgical or radiotherapy treatment. In particular, fractionated radiation therapy offers a radiobiologically safe means of delivering radiation when there is concern for late radiation-related side effects following treatment completion.

Improved depiction of pterygopalatine fossa anatomy using ultrahigh-resolution magnetic resonance imaging at 7 tesla

Purpose. To study the anatomy of the pterygopalatine fossa (PPF) using ultrahigh-resolution magnetic resonance imaging. Methods. A human cadaveric tissue block containing the pterygopalatine fossa was examined on a clinical 7-Tesla magnetic resonance imaging system. Subsequently, cryosections of the tissue block were created in a coronal plane. The cryosections were photographed and collected on adhesive tape. The on-tape sections were stained for Mallory-Cason, in order to detail the anatomic structures within the fossa. Magnetic resonance images were compared with surface photos of the tissue block and on-tape sections. Results. High-resolution magnetic resonance images demonstrated the common macroscopic structures in the PPF. Smaller structures, best viewed at the level of the operation microscope, which have previously been obscured on magnetic resonance imaging, could be depicted. Some of the orbital pterygopalatine ganglion branches and the pharyngeal nerve were clearly viewed. Conclusions. In our experience with one human cadaver specimen, magnetic resonance imaging at 7 Tesla seems effective in depicting pterygopalatine fossa anatomy and provides previously unseen details through its demonstration of the pharyngeal nerve and the orbital pterygopalatine ganglion branches. The true viability of depicting the pterygopalatine fossa with ultrahigh-resolution MR will depend on confirmation of our results in larger studies.

The site of origin and expansive routes of juvenile nasopharyngeal angiofibroma (JNA)

OBJECTIVE

Juvenile nasopharyngeal angiofibroma (JNA) is a rare vascular tumor of the nasopharynx occurring in young males. The aim of this study was attempt to find out the site of origin and the common expansion routes of JNA.

METHODS

The CT examinations of 46 untreated patients with histologically proven JNA were retrospectively analyzed. Evidence of tumor spreading of the locations are those following CT characteristics: (a) expansion and/or erosion of bony wall; (b) obliteration of normal fatty planes. In addition, three dimensional reconstruction technology was used to make further study.

RESULTS

The pterygoid canal was affected in all untreated cases and therefore was considered as the origin of JNA. Nineteen patients' tumors (41.3%) originated from the front part of pterygoid canal and the other 27 ones (58.7%) from the post part of pterygoid canal. Pterygoid canal, choanae and nasal cavity are the three most common sites of JNA.

CONCLUSION

The possible site of origin is pterygoid canal. After originating from this point, the tumor will invade sphenopalatine foramen, sphenoid sinus and pterygopalatine fossa first, and then into adjacent structure through aforementioned three sites.

Skeletal muscle metastases: primary tumours, prevalence, and radiological features

BACKGROUND

Although skeletal muscles comprise nearly 50% of the total human body mass and are well vascularised, metastases in the musculature are rare. The reported prevalence of skeletal muscle metastases from post-mortem studies of patients with cancer is inconstant and ranges from 0.03 to 17.5%.

MATERIALS AND METHODS

Of 5,170 patients with metastasised cancer examined and treated at our institution during the period from January 2000 to December 2007, 61 patients with muscle metastases (80 lesions) were identified on computed tomography (CT). Genital tumours (24.6%) were the most frequent malignancies metastasising into the skeletal musculature, followed by gastrointestinal tumours (21.3%), urological tumours (16.4%), and malignant melanoma (13.1%). Other primary malignancies were rarer, including bronchial carcinoma (8.2%), thyroid gland carcinoma (4.9%), and breast carcinoma (3.3%). In 8.2%, carcinoma of unknown primary was diagnosed.

RESULTS

Skeletal muscle metastases (SMM) were located in the iliopsoas muscle (27.5%), paravertebral muscles (25%), gluteal muscles (16.3%), lower extremity muscles (12.5%), abdominal wall muscles (10%), thoracic wall muscles (5%), and upper extremity muscles (3.8%). Most (76.3%) of the 80 SMM were diagnosed incidentally during routine staging CT examinations, while 23.7% were symptomatic.

CONCLUSION

Radiologically, SMM presented with five different types of lesions: focal intramuscular masses (type I, 52.5% of SMM), abscess-like intramuscular lesions (type II, 32.5%), diffuse metastatic muscle infiltration (type III, 8.8%), multifocal intramuscular calcification (type IV, 3.7%) and intramuscular bleeding (type V, 2.5%).

Microsurgical and endoscopic anatomy of the vidian canal

OBJECTIVE

The vidian canal, the conduit through the sphenoid bone for the vidian nerve and artery, has become an important landmark in surgical approaches to the cranial base. The objective of this study was to examine the anatomic features of the vidian canal, nerve, and artery, as well as the clinical implications of our findings.

METHODS

Ten adult cadaveric specimens and 10 dried skulls provided 40 vidian canals for examination with x 3 to x 20 magnification and the endoscope.

RESULTS

The paired vidian canals are located in the skull base along the line of fusion of the pterygoid process and body of the sphenoid bone. The canal opens anteriorly into the medial part of the pterygopalatine fossa and posteriorly at the upper part of the anterolateral edge of the foramen lacerum. The vidian nerve, when followed posteriorly, reaches the lateral surface of the anterior genu of the petrous carotid and the anteromedial part of the cavernous sinus where the nerve is continuous with the greater petrosal nerve. The bone surrounding the upper part of 12 of 20 vidian canals protruded into the floor of the sphenoid sinus and one canal had a bony dehiscence that exposed its contents under the sinus mucosa. Nine petrous carotid arteries (45%) gave rise to a vidian artery, all of which anastomosed with the vidian branch of the maxillary artery in the vidian canal or pterygopalatine fossa. The vidian canal can be exposed by opening the floor of the sphenoid sinus, the posterior wall of the maxillary, the posterior part of the lateral wall of the nasal cavity, and the medial part of the floor of the middle fossa.

CONCLUSION

The vidian canal and nerve are important landmarks in accessing the anterior genu of the petrous carotid, anteromedial part of the cavernous sinus, and petrous apex.

[Cerebral nerves - perineural tumor spread]

Perineural tumor spread in the course of head and neck tumors is a form of metastatic disease in which the tumor disseminates centrifugally or centripetally along the nerve to (non)contiguous regions. Perineural tumor spread is a potentially devastating complication and has a high impact on the therapeutic management and overall prognosis. In a large proportion of patients the disease remains asymptomatic and imaging (especially MRI) plays a crucial role in the detection of lesions. Familiarity with the pertinent anatomy, knowledge of the common spread pathways and an appropriate imaging strategy allow detection of the perineural spread of the disease in the majority of the cases.

Perineural tumor spread

Perineural spread (PNS) refers to the extent of tumor cells or other nonneoplastic lesions along the tissues of the nerve sheath, its overall incidence ranges from 2.5% to 5%. PNS is more frequently associated with carcinoma arising from minor or major salivary glands (more often adenoid cystic carcinoma), mucosal or cutaneous squamous cell carcinoma, basal cell carcinoma, melanoma, lymphoma, and sarcoma. Although PNS was previously associated with worsening prognosis, increasing evidence shows that cure is possible. Therefore, radiologists must be aware of the relevant cranial nerve anatomy and thoroughly scrutinize not only the nerves close to the primary tumor site but also the whole neural pathways that can be accessed by PNS. Equally critical is knowledge of the radiologic appearance of perineural tumor extension and the best imaging strategies to detect PNS.

Perineural tumor spread in malignant head and neck tumors

Perineural tumor spread (PNS) of head and neck malignancies is a course of disease in which tumor metastasizes along the endoneurium or perineurium. Perineural tumor spread is a potentially devastating complication of head and neck cancer and has a high impact on the therapeutical management and overall prognosis. Imaging plays an important role in the detection of this condition, especially in view of a large number of clinically asymptomatic patients with PNS. Magnetic resonance imaging is the modality of choice in the assessment of PNS because of its multiplanar capability and its superior soft-tissue contrast. Knowledge of normal cranial nerve anatomy and the imaging appearance of perineural tumor extension is imperative in the evaluation of PNS which represents a special challenge in head and neck radiology.

CT anatomy of pterygopalatine fossa and its communications: a pictorial review

In this article, we present a pictorial review computed tomography (CT) anatomy of pterygopalatine fossa and its communications. Since it represents a major pathway for spread of inflammatory or neoplastic disease between the various compartments, being familiar with the high resolution CT appearance of pterygopalatine fossa and its communications is necessary in selected cases. The diagnostic difficulties in determining the intercompartmental spread is discussed.

Intracranial perineural extension of invasive mycosis: a novel mechanism of disease propagation by Aspergillus fumigatus

We describe an immunocompetent woman who had refractory, invasive sphenoid sinus Aspergillus fumigatus infection for which there was radiologic evidence of intracranial perineural spread. The patient responded to a combination of antifungal and adjuvant recombinant cytokine therapy.