Transcranial magnetic stimulation in Doberman Pinschers with clinically relevant and clinically irrelevant spinal cord compression on magnetic resonance imaging.

OBJECTIVE

To evaluate the use of transcranial magnetic stimulation for differentiating between clinically relevant and clinically irrelevant cervical spinal cord compression on magnetic resonance imaging (MRI).

DESIGN

Validation study.

ANIMALS: Clinically normal Doberman Pinschers without (n = 11) and with (6) spinal cord compression on MRI and 16 Doberman Pinschers with disk-associated wobbler syndrome (DAWS).

PROCEDURES: After dogs were sedated, transcranial magnetic motor evoked potentials were recorded from the extensor carpi radialis muscle (ECRM) and cranial tibial muscle (CTM). Onset latencies and peak-to-peak amplitudes were measured. Magnetic resonance imaging was performed to identify spinal cord compression.

RESULTS

There were significant differences in ECRM and CTM onset latencies between Doberman Pinschers with DAWS and each of the 2 groups of clinically normal dogs, but there were no significant differences in ECRM and CTM onset latencies between the 2 groups of clinically normal dogs. There were significant differences in CTM peak-to-peak amplitudes between Doberman Pinschers with DAWS and each of the 2 groups of clinically normal dogs, but there were no significant differences in ECRM peak-to-peak amplitudes among groups or in CTM peak-to-peak amplitudes between the 2 groups of clinically normal dogs. There was a significant correlation between severity of spinal cord compression and ECRM onset latency, CTM onset latency, and CTM peak-to-peak amplitude.

CONCLUSIONS AND CLINICAL RELEVANCE: Results suggested that transcranial magnetic stimulation may be a useful diagnostic tool to differentiate between clinically relevant and clinically irrelevant spinal cord compression identified on MRI alone.