# Transbulbar B-Mode Sonography for Clinical Phenotyping Multiple Sclerosis
## 4 Discussion and Conclusions
In our opinion, PPMS and NMO deserve a separate treatment, considering also the absence of literature data on TBS. Figure 4: Transbulbar B-mode sonography and MRI. (**A**) Transbulbar B-mode sonography and (**B**) magnetic resonance images of the optic nerve sheath diameter (ONSD) of (from left to right) relapsing remitting, transitional, and secondary progressive multiple sclerosis patients. The distance between the external borders of the hyper-echoic area surrounding the optic nerve was quantified as ONSD. Lines 4 and 2 indicate ONSD at 3 and 5 mm from the eyeball, respectively. All magnetic resonance images refer to T2/T1 bFFE sequences, acquired with SENSE (Sensitivity Encoding) Head 8 channels. Note the progressive decrease in ONSD and the MI (0.91; 0.84; 0.77) moving through three different phenotypes of disease. MI Myelination index; MRI Magnetic resonance imaging. To summarize, the neuro-sonographic study of chronic optic neuropathy in terms of ONSD highlights lower values at 5 mm in the SP group, due to the lack of myelin repair, subclinical demyelination, and axonal loss. The latter phenomenon is preponderant during this stage of the disease, given that there is no difference between the RR and SP groups regarding the ONSD at 3 mm from the eyeball. Therefore, involvement of the ON can be described as \"mild\" in ARON-free MS patients. Finally, the MI can add a number of physiopathological elements linked to individual MS patients, meaning that it is also useful in defining their clinical phenotype. On these pathological bases, it can be stated that B-mode sonography represents a useful technique for the documentation of ON atrophy. This application could have clinically important implications in determining the dissemination in space (DIS) or time (DIT) of the pathological process in MS, especially if the diagnostic guidelines incorporate the ON as an MS typical region, as recently proposed by the MAGNIMS (magnetic resonance imaging in multiple sclerosis) group [23]. In this case, TBS could be included in the routine clinical practice of the diagnostic iter of MS. Traslated in clinical terms, our data also suggest a valuable role of B-mode sonography in the clinical phenotyping of MS patients. Given that therapeutic management of MS is closely related subtype individuation, it follows that TBS could provide an objective instrumental criterion for personalized therapeutic choice in MS.  
[PERSON] has made substantial contributions to conception and design, acquisition of data, analysis, and interpretation of data. [PERSON] has been involved in drafting the manuscript and revising it critically for important intellectual content. [PERSON] and P.S. have contributed to acquisition and analysis of data. [PERSON] and R.S. have given final approval of the version to be published. A.D.D. agrees to be accountable for all aspects of the work in ensuring that questions related to the accuracy and integrity of any part of the work are appropriately investigated and resolved. This research received no external funding. We thank our multiple sclerosis nurses, [PERSON] and [PERSON], for technical support and the local ethics committee for approval. The authors declare no conflict of interest.