(1) Rules for evaluation of permanent dorsal area impairments are as follows:

(a) Muscle spasm or involuntary guarding, bony or fibrous fusion, any arthritic condition, internal fixation devices or other physical finding shall be considered, in selection of the appropriate category, only insofar as productive of dorsal area impairment.

(b) Gradations of clinical findings of dorsal impairments in terms of "mild," "moderate" or "marked" shall be based on objective medical tests.

(c) Categories 2 and 3 include the presence of complaints of whatever degree.

(d) Bladder and/or bowel sphincter impairments deriving from impairments of the dorsal area shall be evaluated separately.

(e) Impairments which also involve the cervical or lumbar areas shall be evaluated only under the cervical and cervico-dorsal or dorsolumbar and lumbosacral categories.