Neurology Case of the Month (Oct 2012): LFL lameness in a dogWritten on October 01, 2012 by Mark Troxel, DVM, DACVIM (Neurology) Hospital: Massachusetts Veterinary Referral Hospital

Signalment: 8yr MC Lab

History: The patient was referred to the Neurology Department for evaluation of a 1-month history of progressive left thoracic limb lameness/weakness that was not responsive to NSAIDs and pain management. The right thoracic limb and both pelvic limbs seemed normal to the owner. The dog did not appear to be in overt pain.

Case Video:

Neurological exam:

Mental status: QAR
Gait/posture: Ambulatory with a weight-bearing LFL paresis/lameness
Cranial nerves: WNL
Postural reactions:
Absent CP/hopping LFL, normal CP/hopping other 3 limbs
Spinal reflexes: LFL: Normal biceps reflex (doesn’t show up well on video), decreased extensor carpi, minimal triceps reflex; normal reflexes other 3 limbs
Spinal pain: None
Muscle tone: Normal x 4
Muscle atrophy: Moderate atrophy of left triceps, supraspinatus, and infraspinatus muscles
Pain sensation: Normal x 4
Cutaneous trunci: Absent on left side regardless of which side was pinched

What is your neurolocalization?  What are the top differential diagnoses? (SCROLL DOWN TO SEE ANSWERS)


 

 

 

 

 

 

Neurolocalization = Left brachial plexus or C6-T2 spinal cord

 

 

Differential diagnoses

  • Neoplasia – malignant peripheral nerve sheath tumor, meningioma, lymphoma, histiocytic sarcoma, others
  • Lateralized interveterbral disk protrusion/herniation
  • Inflammatory/infectious diseases

 

Diagnostics

  • CBC/biochemical profile: WNL
  • Thoracic radiographs: WNL for age/breed
  • MRI: Left-sided spinal mass that appears to be intradural/extramedullary with enlargement of the left C7 nerve root

 

Diagnosis
Presumptive malignant peripheral nerve sheath tumor with extension into the spinal canal

 

Treatment
Treatment options included surgery to debulk the spinal mass with a LFL amputation followed by radiation therapy, surgery alone, radiation therapy alone, and palliative relief of symptoms with pain medications & corticosteroids.

 

Prognosis
The prognosis for this patient was poor given the mass within the spinal canal. If the tumor is more peripherally located, surgery +/- radiation therapy can provide a 9-12 months average survival time. Surgery can be curative if the entire tumor can be removed with amputation for more distally located tumors.

 

NOTES

  • Patients with a brachial plexus tumor are often easily misdiagnosed with thoracic limb osteoarthritis because they present with lameness and no other clinical signs. Many of these patients are large breed dogs that commonly have elbow or shoulder arthritis and many have concurrent orthopedic disease.
  • Some clues that help differentiate a neurological from an orthopedic condition include: postural reaction deficits, decreased withdrawal reflex, absent cutaneous trunci reflex on the same side as the lameness due to involvement of the lateral thoracic nerve, and the presence of Horner’s Syndrome (sometimes all you will see is a smaller pupil on the same side).
  • Be sure to assess the ipsilateral hind limb…postural reaction deficits and/or UMN neuron signs suggest that there is spinal cord involvement.

24 Hour Emergency & Specialty

Boston West Veterinary Emergency and Specialty

Natick, MA 01760
508.319.2117

Directions

Capital District Veterinary Referral Hospital

Latham, NY 12110
518.785.1094

Directions

Massachusetts Veterinary Referral Hospital

Woburn, MA 01801
781.932.5802

Directions

Port City Veterinary Referral Hospital

Portsmouth, NH 03801
603.433.0056

Directions

SAVES

Lebanon, NH 03766
603.306.0007

Directions

General Practice, Emergency & Specialty

Bulger Veterinary Hospital

North Andover, MA 01845
ER: 978.725.5544 GP: 978.682.9905

Directions