Article reprinted with permission of DVM360 –September 06, 2018. DVM360
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NEUROLOGY
Salivation Abnormalities of
Neurogenic Origin
Max presented with unilateral temporalis muscle atrophy
but also with changes to his saliva. Let’s investigate what's
behind it.
By Rachel B. Song, VMD, MS, DACVIM (Neurology),
Eric N. Glass, MS, DVM, DACVIM (Neurology),
Marc Kent, DVM, DACVIM
It’s Monday morning. You walk into the office, back
from a long weekend. You run through the list of the
day’s appointments and see that one of your favorite
patients, Max, is on the day’s schedule with the chief
complaint being that the “head looks funny. ”Later that
day, you enter the exam room and ask, “What’s going
on with Max today?”
His owner replies, “Well, doc, the left side of his head
completely sunk in overnight!”
You take one look at Max’s head and your heart
sinks—you quickly recognize that the left temporalis
and masseter muscles have atrophied completely.
Without the muscles, the left zygomatic arch is
clearly visible to the naked eye. The left eye also
has become enophthalmic with an accumulation of
mucoid discharge and third eyelid elevation (Figure
1). Additionally, enophthalmos of the left eye and
secondary third eyelid elevation have resulted from
atrophy of the pterygoid muscles. (All photos courtesy
of Drs. Rachel B. Song, Eric N. Glass and Marc Kent).
When you turn Max’s head to examine the right
side, you see how well-muscled his head is on the
unaffected side. He’s still able to close his eyelids
when you perform the palpebral reflex and the
menace response. You remember that to close the
eyelids, cranial nerve VII (the facial nerve) has to be
functioning normally. Likewise, all the other cranial
nerves appear to have normal function on your
examination. When you do an oral exam on Max,
you see an accumulation of thick, foamy saliva in the
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Issue 04 | SEPTEMBER 2018 | 20
Figure 1: Max has unilateral dysfunction of the mandibular
branch of cranial nerve V (trigeminal). Atrophy of the temporalis
muscle (large arrow) is evident. Loss of the masseter and
temporalis muscles makes the zygomatic arch more clearly
defined (arrowhead).