Time for a Tongue Twister!

Signalment: 12 year old MC Mixed breed dog, 45 kg
History: 1 month history of change in bark, with a 1-2 week history of difficulty eating and drinking. The owners had also identified difficulty walking in the last few days and a decrease in the dog's interaction with them.
Physical Examination: Grade II/VI left heart murmur, previously noted and not progressive. The remainder was unremarkable.

Neurologic Examination

Mentation: Mild obtunded. The pet interacted when asked, but otherwise seemed content to stare at the wall.
Cranial nerves: Decreased to absent gag reflex, tongue atrophy (see the photo above), all remaining cranial nerves were normal.
Gait: Ambulatory mild proprioceptive ataxia in all four legs
Reflexes: Normal spinal reflexes including c. trunci and perineal.
Palpation: Non painful spinal palpation however pain elicited with cervical ventroflexion
Postural reactions: absent right thoracic and right pelvic limb paw replacement test, normal left paw replacement thoracic and pelvic.
Neuroanatomic Lesion Localization??

To do this, we need to break it down and identify all of the possible anatomic localizations each neurologic deficit could be noted. I prefer table form, but flow charts are also great

** The table did not post properly. If you want to see this table, please email me at barnes@barnesveterinaryservices.com

.Do you see what I did here? I listed all the possible locations that the affected deficit might involve and then narrowed down the lesion localization two ways:

Find the common denominator. In this case, the medulla.
Find the cranial nerve(s) affected and determine if the pet also has: a) abnormal mentation, b) hemiparesis ipsilateral to the affected cranial nerve if nerves 5-12, and c) paw replacement deficits ipsilateral to the affected cranial nerve if involving CN 5-12.

Neuroanatomic Lesion Localization

Medulla, right side.

Differential Diagnoses

Neoplasia, meningoencephalitis (infectious or inflammatory)

Case Conclusion

This dog had normal CBC, serum biochemistry, UA, chest radiographs and abdominal ultrasound. Brain MRI identified a discrete contrast enhancing extra-axial mass in the right caudal fossa affecting the right side of the medulla. This finding was most consistent with a brain tumor called a meningioma. A spinal tap was not performed due to the proximity of the mass to the cerebellomedullar cistern. Based on the working diagnosis surgical decompression, radiation therapy or supportive care were discussed with the owners and they elected supportive care.

Key Learning Points:

Dogs with difficulty eating may have neurologic reasons. When you open the mouth to look at the teeth, do not forget to look at the tongue too! The asymmetry and deviation of the tongue secondary to muscle atrophy could be easily detected.
Lesion localization is just a jigsaw puzzle. Remember the main localizers for a central lesion (change in mentation, paw replacement deficits and hemiparesis) and you can localize most cranial nerve lesions to central or peripheral.
Yes, this was an old dog, but I have diagnosed meningoencephalitis in older dogs so neoplasia should never be your only differential. (I cannot say this enough!)

Do you have a case you'd like to discuss with me? Feel free to email, text, or call me! I'm still trying to see mostly video consults whenever possible but I'm gradually increasing the live consults performed. Either way, I look forward to (continuing to) work with you!