Patterns of perineural spread of head and neck malignancies.

Transcription

1 Patterns of perineural spread of head and neck malignancies. Poster No.: C-1234 Congress: ECR 2014 Type: Educational Exhibit Authors: C. Martins Jarnalo, G. Lycklama à Nijeholt, E. Sanchez-Aliaga, J. A. Castelijns ; Amsterdam/NL, Den Haag/NL Keywords: Education and training, Cancer, Diagnostic procedure, MR, CT, Neuroradiology peripheral nerve, Head and neck, Anatomy DOI: /ecr2014/C-1234 Any information contained in this pdf file is automatically generated from digital material submitted to EPOS by third parties in the form of scientific presentations. References to any names, marks, products, or services of third parties or hypertext links to thirdparty sites or information are provided solely as a convenience to you and do not in any way constitute or imply ECR's endorsement, sponsorship or recommendation of the third party, information, product or service. ECR is not responsible for the content of these pages and does not make any representations regarding the content or accuracy of material in this file. As per copyright regulations, any unauthorised use of the material or parts thereof as well as commercial reproduction or multiple distribution by any traditional or electronically based reproduction/publication method ist strictly prohibited. You agree to defend, indemnify, and hold ECR harmless from and against any and all claims, damages, costs, and expenses, including attorneys' fees, arising from or related to your use of these pages. Please note: Links to movies, ppt slideshows and any other multimedia files are not available in the pdf version of presentations. Page 1 of 26

2 Learning objectives Learning objectives -To learn the anatomy of the extracranial nerves and how to recognise these sites on sectional imaging. -To learn the most important routes for spread of malignant disease and what radiological signs to assess. Page 2 of 26

3 Background Introduction: The extra-neurocranial anatomy is a challenging and complex area to master. In the setting of head and neck malignancies it is very important to recognise specific signs and have knowledge of specific routes in order to scrutinise for possible perineural spread. Knowledge of the imaging appearance of perineural spread is important, for it can be very subte and easy to miss. Also the majority of patients do not have clinical signs of perineural spread. Perineural spread: Perineural spread is spreading of tumorous cells along the perineurium and endoneurium of peripheral nerves. Mostly it occurs from the periphery into the central nervous system, but it can also occur in retrograde fashion. It is very important to recognise this entity because it has a detrimental influence on the prognosis. Moreover measures can be taken to minimise further spread, usually by extending the radiation field. Page 3 of 26

4 Fig. 1: Illustration of a peripheral nerve References: smartdraw.com It can be very challenging due to certain facts: - only 30 % of patients report clinical signs of perineural spread - detection of a second mass that has spread perineurally can be at another site as the primary tumor. - the anatomy in the head and neck region of cranial nerves is very complex - radiological signs can be very subtle. Symptoms with which patients can present include: sensibility disorders as hypesthesia, pruritis and muscle weakness due to denervation. As mentioned earlier, only approximately 30 % of patients present with signs of perineural spread. When there are multiple cranial nerves involved, extensive spread could be the case and especially intracranial tumor spread should be explored. Page 4 of 26

5 There are certain histological types of tumor which are especially prone to perineural spread. These are: basal cell carcinomas, adenoid cystic carcinomas and sarcomas. Also certain locations are subdue to perineural spread: nasopharynx, parotid and sublingual glands and deep skin tumors. Finally certain nerves show more perineural spread, especially the facial and trigeminal nerve due to their location and abundant crossings. To diagnose perineural spread, it is important to use special imaging protocols. First of all always include post gadolinium scans. MR imaging is especially recomended, as the threshold for detecting perineural spread is lower than with CT. Thin slices should be used, A T1 without fat sat and without contrast enhancement should be included in the protocol. Also special care should be taken in choosing the right field of view, with the entire face, the skull base and the brainstem, to include all anatomical sights. With CT, it is important to reconstruct in thin slices ( 2mm) and include bone as well as soft tissue filters and reconstruct in three directions. Imaging findings of perineural spread as mentioned before can be very subtle. These constitute of: - Obliteration of fat planes (on CT and MRI) - Enlargement of the affected nerve (on MRI) - Excessive enhancement (on MRI) - Enlargement of the affected foramen (on CT) Page 5 of 26

6 Findings and procedure details Imaging findings of perineural spread as mentioned before can be very subtle. Pay attention to: - Obliteration of fat planes (on CT and MRI) - Enlargement of the affected nerve (on MRI) - Excessive enhancement (on MRI) - Enlargement of the affected foramen (on CT) Be aware that apart from intracranially, the surrounding venous plexus and perineural tissue may enhance physiologically. It is important to compare it with the contralateral side to detect pathological enhancement. Normal Anatomy: Trigeminal nerve: The trigeminal nerve is the thickest cranial nerve which leaves the pons in a rather lateral position. It courses straight through the pre-pontine cistern to enter the Gasserian ganglion. Page 6 of 26

7 Fig. 2: Illustration of the proximal trogeminal nerve References: Leblanc Fig. 3: Coronal (left) and axial (right) CISS The arrows depict the trigeminal nerve in the pre-pontine cistern Page 7 of 26

8 Coursing ventraly the third division of the trigeminal nerve (maxillary branch) is the first one to exit the skull through the foramen ovale. The first branch (ophtalmic/ V1) and the second branch (mandibular/v2) course through the cavernous sinus. The first then courses through the superior orbital fissure; the second through the foramen rotundum. Fig. 4: Coronal T1 From posterior (upper left) to anterior (lower right) Page 8 of 26

9 Fig. 5: Axial (left) and coronal (right) CT of the skull base. Bone window. Fig. 6: Axial (left) and coronal (right) CT of the skull base. Bone window. Fig. 7 More peripherally the three branches have their own course: Ophtalmic (V1): superior orbital fissure >> travels superiorly and branches into lacrimal nerve; nasociliairy nerve and frontal nerve Page 9 of 26

10 Maxillary(V2): after coursing through the foramen rotundum, it gives off small branches which extend caudally to the pterygopalatine fossa (important location of perineural spread) Note that this is in open contact with the inferior orbital fissure. Most of the nerve travel ventrally through the infra-orbital canal. Mandibular (V3): Caudally from the foramen ovale, the nerve enters the posterior part of the masticator space. It then splits into 2 branches: the lingual nerve and the inferior alveolar nerve which courses through the mandibular foramen and through a long canal in the mandibula and exits through the mental foramen. Fig. 8: Illustration of the branches of the trigeminal nerve. References: Pterygopalatine fossa: This fossa deserves special mention because of the extensive routes of spread via this site: - Through the vidian channel to the facial nerve Page 10 of 26

11 - Through the inferior orbital fissure into the orbit - Through the sphenopalatine fossa into the nasal cavity - Directly to the mandibular nerve an then intracranially through the foramen rotundum or the infraorbital nerve. - Directly to the masticator space Facial nerve: After leaving the brainstem the facial nerve enters the internal auditory meatus and travels through the petrosal bone. Is makes a sharp turn at the geniculate ganglion, and after a short horizontal course in a posterior lateral orientation, it courses downward through the stylomastoid foramen. Fig. 9: Illustration of the facial nerve in the petrosal bone References: Netter Page 11 of 26

12 Fig. 11: Axial STIR Patient with facial neuritis. The facial nerve is nicely depicted here, in the descending portion of the petrosal bone. Fig. 10: Axial (left) and coronal (right)t1 post gadolinium. Patient with facial neuritis. The geniculate ganglion is illustrated on the left. On the right the descending portion of the facial nerve is shown. Note the from the geniculate ganglion to the descending part the surrounding vasculature can enhance fysiologicaly, but symetrically. The greater petrosal nerve coming from the geniculate ganglion, travels through the vidian channel to the pterygopalatine fossa. (see also figures: 6, 7 and 8) Page 12 of 26

13 Fig. 12: Coronal T1 Vidian channel with the greater petrosal nerve, coming from the facial nerve and the deep petrosal nerve, coming from the sympathetic trunk. This is an important route of spread to and from the pterygopalatine fossa. The facial nerve then gives off multiple branches which travel through the parotid gland to innervate multiple facial muscles. Cavernous sinus: Once the tumor has reached the cavernous sinus many other nerves can become involved and further spread can become extensive. See figure: Page 13 of 26

14 Fig. 22: Cavernous sinus References: Netter QUIZ CASES Fig. 13: Coronal (left) and axial (right) MR T1 post gadolinium. Page 14 of 26

15 Question 1: through which neuroforamen does this tumor spread, and which nerve goes through this foramen? Fig. 14: Coronal T1 post gadolinium The same patient as in figure 13. The right most image is more ventral. Question 2: Which foramen does arrow 1 point out? which nerve travels through this foramen? Question 3: Most part of the nerve from arrow one travels through arrow number two. How is this nerve called? Page 15 of 26

16 Fig. 15: Axial CT post contrast. Soft tissue window. The arrow points out obliterated fat, notice the normal right side. Question 4: Which foramen is the arrow pointing out? How is the nerve called passing through it? From which nerve does it originate? Page 16 of 26

17 Fig. 16: Axial T1 post gadolinium. Question 5: How is the important anatomical site called at arrow 1? Question 6: To which space has the tumor spread (the primary tumor was located elsewhere) at arrow 2? Page 17 of 26

18 Fig. 17: Axial T1 post gadolinium Case of figure 19. The nerve at the red arrow is at risk, the surrounding tissue enhances avidly. Notice the normal contralateral nerve (circle) Question 7: Which nerve in the masticator space is at risk for perineural spread? Page 18 of 26

19 Fig. 18: From top to bottom: Axial MR T1; MR T1 post gadolinium; CT soft tissue window. Another case with tumor infiltration in the pterygopalatine fossa, spreading directly to the masticator space. Notice the obliteration of the fatplanes compared to the other side. Page 19 of 26

20 Fig. 19: MR axial T1 (left); coronal T1 (right) Notice the tumor of figure 17 spreading upward. Question 8: To which fissure has the tumor spread? Page 20 of 26

21 Fig. 20: MR coronal T1 Case of figure 17. From the inferior orbital fissure the tumor has spread further upward and intracranially. Question 9: Which foramen is pointed out at number 1? Question 10: Which important anatomical location is obliterated intracranially? Page 21 of 26

22 Fig. 21: MR coronal T1 post gadolinium (left) CT coronal bone window no contrast (right) The nerve in the foramen which is pointed out enhances vividly. On CT there is a normal appearance. Question 11: Which foramen is pointed out? It is situated just medial and posterior to the foramen rotumdum. Question 12: Apart from the second division of the trigeminal nerve, which other nerve is at risk and via which nerve does it spread? Answers: Question 1: Foramen ovale; third division of the trigeminal nerve or mandibular nerve. Page 22 of 26

23 Question 2: Foramen rotundum; second division of the trigeminal nerve or mandibular nerve. Question 3: Inferior orbital nerve. Question 4: Mandibular foramen; inferior alveolar nerve; from the thrid division of the trigeminal nerve Question 5: Fossa pterygopalatina Question 6: Masticator space. Question 7: The third division of the trigeminal nerve or mandibular nerve. Question 8: The inferior orbital fissure. Question 9: Foramen rotundum, second division of the trigeminal nerve or mandibular nerve. ( see also question 2). Question 10: Cavernous sinus Question 11: Vidian channel Question 12: The facial nerve, via the greater petrosal nerve Page 23 of 26

24 Conclusion Perineural extension routes of disease in the extra-neurocranial spaces are often overlooked and can be challenging to recognise. Imaging findings of perineural spread as mentioned before can be very subtle. Pay attention to - Obliteration of fat planes (on CT and MRI) - Enlargement of the affected nerve (on MRI) - Excessive enhancement (on MRI) - Enlargement of the affected foramen (on CT) Certain "checkpoints" should always be scrutinised in the vicinity of head and neck malignancies: Pterygopalatine fossa Cavernous sinus Foramen rotundum Foramen ovale Vidian channel Stylomastoid foramen Superior and inferior orbit Remember to compare with the contralateral side. Page 24 of 26

25 Personal information C.O. Martins Jarnalo, M.D. Department of Radiology, Medisch Centrum Haaglanden, The Hague, the Netherlands and VU- Medisch Centrum, Amsterdam, the Netherlands. G.J Lycklama à Nijeholt, M.D. Ph.D. Department of Radiology, Medisch Centrum Haaglanden, The Hague, the Netherlands E. Sanchez-Aliaga, M.D. VU- Medisch Centrum, Amsterdam, the Netherlands prof. J.A. Castelijns, M.D. Ph.D. VU- Medisch Centrum, Amsterdam, the Netherlands Page 25 of 26

26 References Diagnostic imaging Head and Neck. Harnsberger , Amirsys, Inc. Atlas of human anatomy Second Edition. Netter Page 26 of 26