Gait analysis

Gait analysis is an extremely important part of the neurological exam. Too often, insufficient time is spent examining the patient’s gait and body posture. A great deal of information can be obtained before touching the patient. Neurolocalization often can be made simply by analyzing the patient’s gait and body posture.

Allow the patient to explore the exam room while obtaining the patient’s history from the owner. Dogs should be leash-walked by the owner or a staff member, and the patient should be observed walking toward and away from the observer, as well as in profile. Vary the speed of the gait and walk the patient up and down stairs. Walking the dog in circles may help identify crossing-over and ataxia. Ensure adequate traction for the patient to walk, such as concrete, grass, gym mat, or carpet. An inexpensive carpet runner or scrap piece of carpet can easily be unrolled in the hospital for gait analysis and then rolled back up again for easy storage. Alternatively, large rolls of yoga mat material can be purchased online – they are inexpensive, lightweight, easily cleaned and hung to dry, and can be rolled up and stored out of the way.

Evaluate the gait

  • Paresis (weakness): dysfunction of the motor system
  • Ataxia (incoordination): dysfunction of the sensory system
  • Lameness

Strength

There are many ways to describe a patient’s gait, but most neurologists typically first describe the presence of any weakness and whether the patient is ambulatory or nonambulatory. Animals that are weak, but still able to voluntarily move the limbs, are said to be “-paretic,” while animals that are unable to voluntarily move the limbs are said to be “-plegic” (paralyzed). These suffixes are then combined with a prefix to identify which limbs are involved.

  • Mono- = One limb involved (e.g., left pelvic limb monoparesis)
  • Hemi- = Both limbs on same side affected (e.g., right-sided hemiparesis)
  • Para- = Both pelvic limbs affected (e.g., paraplegic)
  • Tetra- = All 4 limbs affected (e.g., nonambulatory tetraparesis)
  • Stride length can help localize the lesion. A long-strided gait is usually a sign of an upper motor neuron (UMN) disorder, while a short-strided gait can be a sign of a lower motor neuron (LMN) spinal cord, peripheral neuromuscular, or orthopedic condition.

I’ve seen the term “nonambulatory paraplegic” used quite a bit in veterinary medicine. Technically, this is redundant since patients that are paraplegic are, by definition, unable to ambulate.

Grading system

olby-gait-scoring-chart

Ordinal scale used to score gait. Used with permission (open access) from Olby et al.: Gait scoring in dogs with thoracolumbar spinal cord injuries when walking on a treadmill. BMC Veterinary Research 2014 10:58.

Listed below is one commonly used grading system to describe the patient’s gait. Dr. Natasha Olby and colleagues developed a separate 14-point grading system with greater detail (see Table at right) for their research studies.

0 = Paralyzed
1 = Nonambulatory with severe paresis (only slight voluntary movement) and ataxia
2 = Nonambulatory with moderate to severe paresis and ataxia
3 = Ambulatory with moderate to severe paresis and ataxia
4 = Ambulatory with mild to moderate paresis and ataxia
5 = Normal gait

Author’s opinion: Personally, I find these grading systems somewhat difficult to use on the clinic floor. They are excellent to use in studies for statistical analysis, but since there is no standard grading scale, using a grading system in clinics can lead to confusion between clinicians. I prefer to describe the patient’s gait, such as “Nonambulatory with moderate to severe parapresis (left worse than right) and proprioceptive ataxia.”

Incoordination

Next, describe the presence of incoordination (ataxia), a sensory phenomenon. In general, ataxia is present when the feet do not consistently land in the appropriate location while the patient is walking. There are three forms of ataxia:

  • Proprioceptive ataxia (a.k.a, general proprioceptive, spinal)
  • Vestibular ataxia
  • Cerebellar ataxia

Each of these types of ataxia is described below. It is not uncommon to observe features of two forms of ataxia in the same patient. For example, some patients display a combination of cerebellar and vestibular ataxia due to disease affecting the vestibular components of the cerebellum (flocculus, nodulus, fastigial nucleus, caudal cerebellar peduncle).

Proprioceptive ataxia

Proprioceptive ataxia is often characterized by scuffing or dragging the paws on the ground, knuckling over, crossing over, or interference (limbs hitting each other when walking). In general, patients with proprioceptive ataxia will walk with their whole body in a straight line, even if the hind end is off to one side or the other, while patients with vestibular or cerebellar ataxia usually will not walk in a straight line. A wide-based stance/gait is more common with UMN dysfunction, while a narrow-based gait is more common with LMN spinal cord, neuromuscular, or orthopedic disease.

Vestibular ataxia

Patients with vestibular ataxia are unable to walk in a straight line. Frequent observations include circling, veering or drifting, leaning, stumbling, falling, or rolling. These abnormalities usually are toward the side of the lesion. A wide-based gait/stance is common and some patients will “flail” the legs out laterally when lifted off the ground.

Cerebellar ataxia

Cerebellar ataxia is most often visible as dysmetria, in which the patient either overshoots or undershoots the intended target. Paresis is not a feature of cerebellar ataxia, although moderately to severe affected animals may appear to be weak due to the severity of their disease. Hypermetria is most common, in which there is over flexion of the elbows, hips, and stifles. Other features of cerebellar ataxia include spastic gait, truncal sway/ataxia, falling, intention tremors and wide-based stance.

NOTE

One of the more common gait abnormalities seen in veterinary neurology is a “long-strided, floating gait.” This is a sign of an UMN lesion to the affected limbs. Many people misinterpret this floating gait as hypermetria and incorrectly localize the lesion to the cerebellum. The Pug in the video under Proprioceptive Ataxia above has a C1-C5 spinal cord lesion. Notice how the dog’s limbs seem to float in the air before contacting the ground and the elbows remain extended. While this is technically a form of hypermetria, when you hear/think about the word “hypermetria,” you would think of a cerebellar disorder. With cerebellar hypermetria, there is excessive flexion of the elbows.

Body posture

Head tilt

Head tilt is one of the classic signs of vestibular dysfunction. Be careful to distinguish a head tilt, in which one eye is lower than the other, from a head turn, in which the eyes remain parallel to the ground with the head turned to one direction. Some describe a head tilt as one ear lower than the other, but care must be taken as facial nerve dysfunction can lead to a droopy ear giving a false impression of a head tilt. The head tilt is usually toward the side of the lesion (see vestibular dysfunction for additional information). Head tilt occurs with both peripheral and central vestibular dysfunction and does not localize the lesion to one or the other system. Patients with bilateral peripheral vestibular dysfunction (e.g., bilateral otitis interna) may not have a head tilt.

Neurolocalization: Vestibular system, usually ipsilateral, central or peripheral

Head tilt

Right head tilt in a cat with otitis media-interna.

Head turn

Head turn is most often a sign of forebrain dysfunction with the direction of head turn being toward the side of the lesion. Occasionally, torticollis is noted in patients with cervical muscle spasms or discomfort that may be misinterpreted as head turn.

Neurolocalization: Ipsilateral forebrain > cervical spine

Right head turn in a dog with a right cerebral brain tumor.

Right head turn in a dog with a right temporal lobe mass (presumptive glioma).

Arched back

An arched back can be a sign of neck or back pain, as well as a sign of abdominal pain. In each instance, the patient assumes this position to alleviate discomfort. With neck pain, the patient arches the back to take pressure off the thoracic limbs, thereby reducing pain.

Neurolocalization: Spinal hyperpathia most common – rule out cervical vs. thoracic/lumbar discomfort

Arched back in a dog with a cervical disc extrusion.

Arched back in a dog with a cervical disc extrusion.

Root signature

A root signature is a body posture in which a patient with nerve root compression (e.g., lateralized IVDD) holds the limb off the ground. This is more common in the thoracic limbs than pelvic limbs, and, in this author’s experience, more common in small breed dogs compared to large breed dogs. Less severely affected patients may show only weight-bearing lameness when walking.

Neurolocalization: Ipsilateral C6-T2 or L4-S1 depending on limb affected

Root signature

Right thoracic limb root signature in a Boston Terrier with a C6-7 intervertebral disc extrusion.

Schiff-Sherington

Schiff-Sherington posture is characterized by rigid extension of the thoracic limbs in patients in patients with T2-L4 spinal cord dysfunction. This posture occurs when there is severe injury to ascending inhibitory neurons in the cranial lumbar spinal cord or to their axons that project cranially to synapse on lower motor neurons to the thoracic limbs. Disinhibition of thoracic limb lower motor neurons leads to increased muscle tone and rigid thoracic limbs.

Neurolocalization: Spinal cord, T2-L4

Schiff-Sherrington

Schiff-Sherrington posture in a Labrador Retriever with acute non-compressive nucleus pulposus extrusion (“traumatic disk”).

Decerebellate rigidity

Decerebellate rigidity is characterized by extension of the thoracic limbs and flexion of the pelvic limbs. Opisthotonus is usually present. These patients remain conscious unless the brainstem or diffuse forebrain is also involved.

Neurolocalization: Rostral cerebellum

Decerebellate rigidity

Decerebellate rigidity in a dog with a mass at the cerebellomedullary angle.

Decerebrate rigidity

Decerebrate rigidity is characterized by rigid extension of all four limbs and opisthotonus, and is due to a midbrain lesion causing disruption of descending inhibitory upper motor neurons (UMN). Loss of UMN inhibition on the extensor muscle lower motor neurons of the limbs and neck results in excessive excitation and, thus, extension of the limbs and neck.

Patients with C1-C5 spinal cord upper motor neuron dysfunction may also present with rigid extension of all four limbs, but patients with decerebrate rigidity have impaired consciousness, while patients with C1-C5 spinal cord dysfunction remain alert and responsive.

Neurolocalization: Rostral brainstem (midbrain)

Decerebrate rigidity

Decerebrate rigidity in a dog with a large pituitary mass causing transtentorial herniation.

Cervical flexion

Cervical flexion is characterized by downward deviation of the head/neck. An attempt should be made to determine whether the patient’s cervical flexion is an active or passive process. Patients with active cervical flexion will actively resist the head being lifted and may display overt signs of discomfort while patients with passive cervical flexion will not resist elevation of the head and are unable to hold the head up if not held in place. Passive cervical flexion is typically due to a peripheral neuromuscular disorder.

Differential diagnoses for passive cervical flexion:

  • Hypokalemia (dog/cat)
  • Thiamine deficiency (cat)
  • Hyperthyroidism (cat)
  • Chronic kidney failure (dog/cat)
  • Myasthenia gravis (primarily cats)
  • Other neuromuscular disorders possible
Cervical flexion dog & cat

Cervical flexion in a cat with thiamine deficiency and a post-partrurient dog with hypokalemia due to poor diet.