Tram-track sign (orbit)
Tram-track sign refers to the parallel thickening and enhancement around the optic nerve, and is most frequently seen in the setting of optic nerve meningioma. It may however also be seen in 1:
- orbital pseudotumour
- perioptic neuritis
- orbital sarcoidosis
- oribtal leukemia
- orbital lymphoma
- orbital metastases
- perioptic haemorrhage
- Erdheim-Chester disease
It is helpful in distinguishing dural diseases from optic nerve glioma. However, it should be noted that in some cases the nerve sheath can be diffusely thickened and therefore mimicking the appearance of a optic nerve meningioma 2.
It should not be confused with other tram-track signs elsewhere in the body.
- 1. Kanamalla US. The optic nerve tram-track sign. Radiology. 2003;227 (3): 718-9. doi:10.1148/radiol.2273010758 - Pubmed citation
- 2. Hendrix LE, Kneeland JB, Haughton VM et-al. MR imaging of optic nerve lesions: value of gadopentetate dimeglumine and fat-suppression technique. AJR Am J Roentgenol. 1990;155 (4): 849-54. doi:10.2214/ajr.155.4.2119121 - Pubmed citation