Good question. What makes this an EV case?
First, lets be clear. One doesn’t HAVE to conceptualize this case as an EV case. My goal, anyway is to try to figure out why Ye may have found it helpful to do so.

I’ve been working on a “commentary” to this case. Here’s a very early “draft.”

Another of Ye’s extraordinary vessel cases concerning the wei vessels illustrates his overall understanding of extraordinary vessel function. In that case record he states, “the eight vessels belong to the liver and they are the binding network of the entire body.” 八脉隶乎肝肾, 一身纲维。Here we see that Ye first and foremost understands the extraordinary vessels as a coherent unit performing a variety of functions throughout the body. One of these functions is to provide an energetic matrix for its structure. This is one reason that the extraordinary vessels are so closely linked to the network vessels which are the means bv which the extraordinary vessels carry out this role. Ye’s cases contain many examples of this sort of generalized thinking with regard to the extraordinary vessels.

To be sure, each of the extraordinary vessels has its own set of functions and symptoms. For Ye, chills and feverishness 寒热 is the key symptom of the yang wei, and ‘heart” (or epigastric) pain 心痛is the key symptom of the yin wei and these figure prominently in a number of Ye’s extraordinary vessel cases. Yet in many of his case records, it is most helpful to understand his references to a specific extraordinary vessel as a form of shorthand that refers to a particular function of the entire extraordinary vessel system. For instance, it is the yin and yang wei pair that is traditionally understood as providing the binding network for the entire body and that is why Ye refers to the yin and yang wei in the case of Tang above. On one level at least, he’s referring to the function of the entire extraordinary vessel system that concerns the binding network.
Whether this binding network is either generally associated with the all of the extraordinary vessels or specifically associated with the wei vessels, for Ye it can either become too loose or too tight. He asserts that “the eight vessels [may] exhaust their function of restraint and containment”八脉乏束固之司, and in this instance Ye uses astringing methods. Or, as in the case of Tang above, the binding network has become obstructed by cold. In this case, however, Ye’s emphasis is on the role of the wei vessels as functional pair in physiologically binding the structure.

The location of the problem and its proximity to the trajectories of the yin and yang wei vessels cannot be ignored. Both of the wei vessels traverse the ribs and flanks. Yet, this just leaves us wondering why Ye didn’t just describe the problem in terms of the shao yang and jue yin channels as he did in so many of his other other cases involving rib and flank pain. Although many of Ye’s cases involve rib pain, obstruction patterns and the network vessels, these are not conceptualized in terms of the extraordinary vessels. Clearly, the location of the problem along the wei vessel trajectories, even with a network vessel involvement is not in itself sufficient to invoke the extraordinary vessels. Other criteria are necessary.

From the brief discussion in the Tang case emphasizing the affliction of the network vessels by stagnancy and cold, one might conclude that Ye considers this to be primarily an excess presentation. Ye’s herbal prescription suggests otherwise. Although he makes no mention of a deficiency component in this case, it is apparent that the cold obstructing the networks is rooted in a substantive yang/essence insufficiency. The first ingredient in the prescription is lu jiao shuang warms which along with and sha yuan zi warms and nourishes the liver kidneys and essence. Moreover, the combination some form of lu Rong, sha yuan zi, dang gui and fu ling appears in a number of Ye’s other extraordinary vessel case records where he explicitly identifies the deficiency component as the primary pathodynamic.

In analyzing Ye’s cases, one’s conclusions are necessarily provisional. An almost identical constellation of ingredients appears at least one other case where he makes no mention of the extraordinary vessels. On the other hand, one must consider that Ye’s central point in that particular case was that because the patient was elderly, an approach involving draining fire, opening and disinhibiting was unlikely to be effective 非若少壮泻火通利可效. In the case of Tang too, Ye specifically mentions that the patient is an elderly woman妪, and a progressive deterioration of essence is assumed in both situations. Ye’s brief comments on either case merely illustrate the points that he, or more likely, the student recording the case, finds most salient about them. One might argue, albeit cautiously, that the presence of these ingredients suggests an extraordinary vessels involvement in this case.

The prescriptions in some of Ye’s other extraordinary vessel case records clearly contain a significant number of ingredients that are known to specifically enter the specific extraordinary vessels involved. In the case of Tang however, the association between the wei vessels and the ingredients in the prescription is rather more tenuous. Guizhi is historically linked to the yang wei at least as far back as Zhang Jiegu. The association of xiao hui xiang with the yin wei appears to have originated with Ye himself. Here too, however, there are more instances where Ye appears to use xiao hui xiang in cases where he refers to the extraordinary vessels in a much more generalized context, even when there are symptoms supporting a more specific diagnosis of a wei vessel disharmony.,

So, the above case is and EV case for ye because it meets all of the following criteria.
EV related network vessel involvement.
EV associated symptom presentation
Essence insufficiency.