Neurologic Conditions and Physical Rehabilitation of the Neurologic Patient

William B. Thomas, Natasha Olby and Lisi Sharon

General Considerations

From Olby N, Halling KB, and Glick TR: Rehabilitation for the Neurologic Patient, Vet Clin North Am Small Anim Pract 35(6):1389-1409, 2005.

Typical objectives in rehabilitating the patient with neurologic disease are to minimize pain, reestablish normal neural pathways, prevent secondary complications, and ultimately return the animal to independent function. It is also essential not to worsen neurologic function or pain in patients with spinal instability.

Neurologic conditions are often very painful. Adequate analgesia is important to achieve a successful outcome. Pain-free animals are relaxed and cooperative, recover faster and more completely, and owners are much happier and more compliant with recommendations when their pet is comfortable. Pain originates from multiple sources. Nociceptors respond to a variety of stimuli, including mechanical (e.g., pinching a toe), thermal (heat, cold), and chemical. Activation of superficial mechanical or thermal nociceptors initiates sharp, pricking pain that is precisely localized and ceases when the stimulus is no longer present. Increased intensity of stimulus activates slower conducting pain felt as burning or throbbing that is poorly localized. With tissue injury and inflammation, this type of pain persists even after the initial injury. Patients with neurologic disease can develop neuropathic pain, including spontaneous pain, paresthesia (tingling, prickling), and dysesthesia (paroxysmal shooting, shocklike pain or continuous burning pain). One of the most common causes of neuropathic pain is intervertebral disk herniation that compresses or stretches a nerve root.¹

Analgesic and antiinflammatory drugs are important in managing pain in neurologic patients. Rehabilitation modalities are used to supplement medications and reduce drug requirement. Cryotherapy (see Chapter 18) reduces pain through the gate control theory described by Melzack and Wall that is governed by balance between excitation and inhibition in the dorsal horn, slowed nerve conduction velocity and increased threshold to nerve stimulation. Duration of analgesia lasts at least 30 minutes posttreatment providing an opportunity to perform passive manipulation. Transcutaneous electrical nerve stimulation (see Chapter 20) also works under the same gate control theory (Figure 34-1). Laser therapy (see Chapter 21), and massage (see Chapter 27) may also reduce pain and enhance relaxation.

Figure 34-1 Transcutaneous electrical nerve stimulation applied to a patient for pain control.

Restoring normal function entails a number of exercises, including assisted standing, walking, and swimming. The therapist supports the patient as necessary to give the animal confidence and security when standing and walking. The center of gravity is just behind the scapula, meaning more weight is borne by the thoracic limbs than the pelvic limbs in normal animals. The best way of supporting the animal is to relieve weight from the affected limb(s) and maintain the center of gravity in the correct place by supporting the patient under the sternum and under the pelvis. This minimizes stress on the lumbar vertebrae and allows the cervical vertebrae to move freely. Patients are not supported under the abdomen because this places pressure on abdominal organs and stresses the lumbar vertebrae. Similarly a neck collar is not used to support the patient because this puts pressure on the trachea and cervical vertebrae. A harness that supports the thorax and another to support the pelvis are helpful in larger patients.

When the patient is standing, the therapist helps place the limbs in a normal position. The normal stance is a rectangular configuration in which the feet are at each corner of the rectangle, with each thoracic limb directly under the shoulders and each pelvic limb under the pelvis. The spine should be in a straight line from the head to the tail. With thoracic limb pain, the patient redistributes the weight to the other three limbs, shifting weight and center of gravity caudally, resulting in a stance in the configuration of a triangle. The affected limb is placed laterally, cranially, or caudally and the spine curves toward the unaffected side to maintain equilibrium. This posture overloads the hips and knees. When a thoracic limb is paretic and not painful (e.g., brachial plexus avulsion), the affected limb may be placed caudally and the neck and head may drop ventrally, shifting the center of gravity cranially.

If one pelvic limb is affected, the other pelvic limb is placed medially, the thoracolumbar spine curves to the unaffected side, and the head and neck drop ventrally, shifting the center of gravity cranially. This increases stress on the biceps tendons, elbows, and carpi. When both pelvic limbs are paretic they tend to be placed medially and the thoracic limbs are placed laterally and caudally, with the paws pointing laterally. The head and neck drop ventrally head to shift the center of gravity cranially. This overloads the shoulders, biceps tendons, elbows, and carpi. The thoracolumbar spine is curved dorsally (kyphosis).

A good time to correct the stance is meal times. Although the patient is occupied with eating, gently correct the stance to a normal position (Figure 34-2). Repeat this as needed to maintain a proper stance.

Figure 34-2 While the patient is eating, the stance may be corrected and gentle weight shifting exercises may be performed.

Neurologic patients are at risk of several complications including shortening of ligaments and tendons, muscle atrophy and contracture, pressure sores, urinary tract infections, and respiratory tract infections that can develop secondary to immobility, recumbency, and altered biomechanical stresses. Modalities such as passive range of motion (PROM) and stretching exercises decrease the risk of contractures. Dry, well-padded bedding and frequently repositioning recumbent patients help prevent pressure sores (Figure 34-3). Bony prominences such as the ischiatic tuberosity, greater trochanter, and xiphoid are inspected frequently to detect early skin lesions. Urine retention is prevented by urethral catheterization or manual bladder expression (see Chapter 16). Helping the patient maintain a normal, upright posture as much as practical minimizes many of the adverse effects of recumbency. Patients with loss of sensation or abnormal sensation are at risk of damaging their limbs from dragging or self-mutilation (Figure 34-4). In these patients, the affected limb(s) should always be protected to prevent trauma.

Figure 34-3 Dry, well-padded bedding and frequent repositioning of recumbent patients help prevent pressure sores.

Specific neurologic diseases and their management are discussed in the following sections.

Intervertebral Disk Disease

Intervertebral disk (IVD) disease is a syndrome of pain or neurologic deficits, resulting from displacement of part of the disk. Disks are interposed between each vertebral body except the first and second cervical vertebrae and each of the fused sacral vertebrae. The IVD is situated between adjacent vertebral end plates and is composed of an outer fibrous ring, the annulus fibrosus, which surrounds an eccentric amorphous gelatinous center, the nucleus pulposus.²

Intervertebral disk herniation is a general term that refers to displacement of a portion of the disc. Although a normal disk can herniate as a consequence of major trauma, most herniations are secondary to preexisting degeneration of the disk. Disk degeneration is associated with decreased water and proteoglycan concentration. This reduces the ability of the disk to function as a hydraulic cushion and predisposes to displacement of a portion of the disk. There are two types of disk degenerations, chondroid and fibrous metaplasia. Chondroid metaplasia is most common in chondrodystrophic breeds and causes a progressive transformation of the gelatinous nucleus pulposus to hyaline cartilage. This type of degeneration predisposes to disk extrusion where disk material is displaced beyond the outer edge of the annulus (also called Hansen Type I).

Fibrous metaplasia is an age-related degenerative process that occurs in any breed but is more common in nonchondrodystrophic dogs 7 years of age and older. It is characterized by a fibrous collagenization of the nucleus pulposus and degeneration of the annulus fibrosus. Fibrous metaplasia predisposes to disk protrusion, in which disk material is displaced from the disk space but is contained within an intact annulus (also called Hansen Type II). Nonchondrodystrophic breed dogs can also suffer extrusions and less commonly chondrodystrophic breeds suffer protrusions.2,3

The lifetime prevalence for intervertebral disk disease is approximately 3.5% and overall mortality rate attributed to disk disease is about 1%. Miniature dachshunds have the highest risk, with a lifetime prevalence of 20% and other chondrodystrophic breeds are also at increased risk.⁴

Diagnosis is based on clinical features and imaging studies, including radiography, myelography, computed tomography (CT), and magnetic resonance imaging (MRI). Survey radiographs are useful at ruling out other diagnostic possibilities, such as fractures/luxations, vertebral tumors and diskospondylitis, but are usually not accurate enough for surgical planning for intervertebral disk disease. Myelography is more accurate than survey radiographs but carries a risk of complications such as seizures and worsening of neurologic signs. Computed tomography is accurate for acute extrusions in chondrodystrophic breeds and is noninvasive and usually faster than myelography. However, CT is not as sensitive for noncalcified herniations. Magnetic resonance imaging is generally considered the best diagnostic modality and is accurate and noninvasive, but is also expensive.

Cervical Disk Disease

Cervical disk disease commonly affects small, middle-age to older chondrodystrophic breeds, with beagles and dachshunds having the highest risk.4,5 The C2-C3 disk space is most commonly affected, with the frequency decreasing at progressively more caudal disk spaces. Cervical disk disease in large-breed dogs is usually associated with cervical spondylomyelopathy and is discussed separately. Neck pain is the most common and often the only sign of cervical disk disease and is present in approximately 90% of affected dogs.⁵ This is manifested as low head carriage, stiffness or decreased motion of the neck, vocalizing, and spasms of the neck muscles. Some dogs exhibit lameness of one or both thoracic limbs, owing to nerve root or spinal nerve attenuation (root signature). In severe cases, there is ataxia, conscious proprioceptive deficits, weakness, or paralysis of all limbs. Spinal reflexes are usually normal to exaggerated, although reflexes may be weak or absent in the thoracic limbs with caudal cervical disk extrusions and occasionally with more cranial lesions.⁶ Other causes of cervical lesions include trauma, neoplasia, meningitis, discospondylitis, cervical spondylomyelopathy, and atlantoaxial instability.

Treatment options include surgery and nonsurgical therapy, with the decision based on the duration and severity of clinical signs. Nonsurgical therapy is indicated as the initial treatment in patients with no or mild neurologic deficits. The most important aspect of treatment is strict cage confinement to minimize stress on the damaged disk to allow the disk time to heal. A harness is used instead of a neck collar and leash. A short course of antiinflammatory doses of corticosteroids or nonsteroidal antiinflammatory drugs (NSAIDs) is administered if necessary for pain control. Muscle relaxants may be beneficial in some patients with spasm of the cervical muscles. Analgesic drugs without cage confinement are contraindicated because they may lead to increased patient activity and risk further disk extrusion. If the patient does well, cage confinement is continued for at least 2 to 3 weeks. About 50% of dogs with neck pain caused by disk disease recover with nonsurgical therapy. Recurrence of signs occurs in about one third of patients.⁷

Surgery is indicated for patients with substantial neurologic deficits, neck pain unresponsive to appropriate nonsurgical therapy, or recurrent bouts of neck pain. Removal of extruded disk material by a ventral slot to decompress the spinal cord and nerve roots is the procedure of choice in most patients. Dorsal hemilaminectomy may be necessary for lateral or far-lateral extrusions. In chondrodystrophic dogs, prophylactic fenestration of the other disk spaces at the time of ventral slot is indicated to decrease the risk of extrusion of another disk. Fenestration alone of the affected disk is not indicated because it does not allow removal of extruded disk material.⁸ In dogs with neck pain and mild neurologic deficits, the success rate with surgery is about 95%. Nonambulatory dogs have a good outcome in 62% to 100% cases, with small dogs (≤15 kg) having a better prognosis than larger dogs.^5,8,9 Preoperative, intraoperative, and postoperative management included drugs described for medical management. Postoperative physical rehabilitation is an integral part of the overall care of the patient.

Physical Rehabilitation for Cervical Disk Disease

The most severe cervical injuries cause tetraplegia with a compromise of respiratory function. It is imperative that respiratory function is evaluated in any tetraplegic animal and that respiratory complications (such as pneumonia or hypoventilation) are identified and understood before any exercises that may exacerbate the problem.

Physical rehabilitation as part of medical management includes massage, heat therapy, electrical stimulation (ES), therapeutic ultrasound (US), therapeutic laser for muscle spasms and pain relief. Whirlpool therapy may also be cautiously used in patients carefully supported in a sling as long as there is no struggling (Figure 34-5).

Figure 34-5 Whirlpool with hydraulic hoist and sling.

Postoperative therapy is staged and begins immediately or within 48 hours of surgery to relieve pain and muscle spasms. Modalities such as cryotherapy, ES, carefully administered US, laser and massage may be used based on the clinical needs of the patient. In ambulatory patients, neck leashes should not be used, and leashes should be attached to a harness or across the chest and under one thoracic limb.

Methods of actively eliciting cervical motion begin in the first few days after comfort is achieved and there is no pain on movement of the neck. Active range of motion can be achieved using toys or treats to motivate the patient to turn the head and neck in all directions. Begin with smaller movements and progress to the point that the patient is able to take a toy or treat from near the rear limbs for lateral excursion, between the forelimbs for cervical flexion, and high above the head for extension. Pain-free PROM, stretching, and massage are used to help treat muscle spasms.

Resistive exercises are used in tetraparetic, paraparetic, and hemiparetic patients. Pushing on the bottom of the foot of an extended extremity elicits a flexor withdrawal reflex causing flexion of the limb that stimulates muscles, tendons, ligaments, joints, and bones of the limb. While maintaining limb extension and force on the foot, move the limb slightly in all directions. As the reflex causes the limb to retract, active, resistance can be achieved by the therapist holding the foot, creating a gentle “tug-of-war’’ in which the patient is pulling more forcefully to withdraw the limb from the therapist’s grip. This exercise should be performed for three to five repetitions per limb, three to four times per day.

Assistance should be provided to patients that are able to stand and support weight to attain correct limb placement. Careful use of a sling and hoist may be useful in larger nonambulatory patients. Necessary support through the chest is provided as needed to invoke as much independent weight bearing as possible. Patients are assisted in slow ambulation by placing and moving any limbs with motor deficits. Assisted walking (tail, sling), proprioception stimulation, and limb placement exercises facilitate neuromuscular re-education and proprioceptive functioning, as well as muscle strengthening.

Spinal walking is a phenomenon that occurs in cats following surgical transection of the spinal cord and occurs in some dogs after an injury that causes severe spinal cord injury or transection. While these dogs do not regain normal motor function, spinal walking may be a functional mode of ambulation for short distances.

For strengthening, underwater treadmill walking or swimming may be initiated after the incision site is healed. The time of suture removal is generally a safe time to start hydrotherapy. Some therapists start some form of aquatic therapy earlier, with caution to avoid submersion of the incision, especially an incision in the ventral cervical region. In any case, the incision should be sealed, with apposed edges, no discharge or drainage, and no separation of the incision with gentle manipulation of the edges. In small dogs, a whirlpool may be used for aquatic therapy. The duration of aquatic therapy depends on the fitness, endurance, and ability of the patient. Assistance or life preservers are provided as required (Figure 34-6). If the patient does not actively move its limbs through an adequate range of motion, assistance is given either by passively moving the limb(s) or by providing resistance to motion to stimulate the patient to engage the limb against the applied resistance.

Figure 34-6 Life preserver used for flotation.

Patients can be placed on exercise rolls to strengthen proprioception and joint stability. They may be further challenged with mild bouncing and slight movements of the ball to create an unstable surface (Figure 34-7). Requiring patients to walk on foam, bubble wrap, or an inflatable object or challenging them with a rocker board (Figure 34-8) will also help them to develop stability and proprioception. To assist in regaining kinesthetic awareness, patients can be challenged to step over objects of varying shapes and sizes (Figure 34-9). Small objects are initially used; the height and width are increased as the patient progresses. Strengthening the thoracic limbs can be achieved by ambulating on land, a dry treadmill (Figure 34-10), and deep water and underwater treadmill hydrotherapy. Additional strengthening exercises include walking down inclines with variable pitch, wheel barrowing (Figure 34-11), and increased weight bearing with an exercise roll beneath the pelvic limbs (Figure 34-12). Analogous exercises may be used to strengthen the rear limb muscles, such as walking up inclines, dancing, and weight bearing with the forelimbs on an exercise roll.

Figure 34-7 Therapy roll used for improving conscious proprioception.

Therapeutic modalities are provided for a minimum of 3 weeks. Owners are instructed further in performing strengthening exercises after discharge. Continued rehabilitation modalities are often prescribed after discharge on a recommended weekly schedule.

Thoracolumbar Disk Disease

Thoracolumbar herniations are most common from T12-T13 to L1-L2, although other areas may also be affected. dachshunds, cocker spaniels, and beagles and other chondrodystrophic breeds are at increased risk.⁴ Type I extrusions are most common in these breeds. Type II protrusions are more common in large, nonchondrodystrophic dogs, but large dogs can also suffer acute, Type I extrusions.¹⁰

Onset of signs can be sudden or gradual and depend on the force, quantity, and location of the disk material and the duration of disk herniation. About 10% of affected dogs have back pain with no neurologic deficits. They are often reluctant to run, jump, or climb stairs and may have kyphosis. Neurologic deficits range from mild ataxia of the pelvic limbs to complete paraplegia with urinary and fecal incontinence and absent deep-pain perception. The neurologic deficits may be symmetric or worse on one side. Spinal reflexes are usually normal to exaggerated, but are weak to absent if the extrusion occurs caudal to L2-L3. In the most severe cases, progressive ascending-descending myelomalacia may result. In this syndrome, the spinal cord is damaged progressively cranial and caudal from the initial site. This is recognized in patients with an initial thoracolumbar lesion as a loss of pelvic limb reflexes, loss of abdominal muscle tone, cranial migration of the level of anesthesia and the cutaneous tunic reflex, thoracic limb paresis, and ultimately respiratory arrest. This is a grave condition that the therapist should be aware of if the neurologic status deteriorates.

Other diagnostic considerations for thoracolumbar spinal lesions include trauma, fibrocartilaginous embolism, degenerative myelopathy, discospondylitis, degenerative lumbosacral stenosis, neoplasia, meningitis, and orthopedic conditions such as severe hip dysplasia or bilateral cranial cruciate ligament insufficiency.

About 85% of dogs with back pain and no neurologic deficits will improve with nonsurgical therapy, as described for cervical disk disease. Surgery is indicated in patients with substantial neurologic deficits, or back pain refractory to nonsurgical therapy. Patients with a sudden onset of severe neurologic deficits need urgent surgery. Removal of extruded disk material via hemilaminectomy is the procedure of choice in most cases. Fenestration of the affected intervertebral disk space is routinely performed. Prophylactic fenestration of other thoracolumbar disk spaces reduces recurrence in chondrodystrophic breeds.¹¹ The prognosis depends in large part on the severity and duration of the neurologic deficits. The recovery rate for nonambulatory dogs with acute extrusions and intact deep pain perception is 85% to 95%, with most patients regaining ambulation in 1 to 4 weeks. For dogs with loss of deep pain perception, the recovery rate is about 50% if surgery is performed within 24 hours of the loss of deep pain. This decreases further if surgery is delayed for longer than 24 hours. The recovery rate for large breed dogs with chronic protrusions is much lower, ranging from 22% to 52%.⁴

Physical Rehabilitation for Thoracolumbar Disk Disease

Although physical rehabilitation has been used with pharmacologic intervention in the conservative management of acute and recurrent thoracolumbar disk disease with some success, it is important to perform minimal intervention and avoid motions that might risk further herniation of disk material for one month; the major application of therapeutic modalities is in the postoperative period. The initiation of therapy and protocols used are similar to those used for cervical disk patients, but the focus is on the pelvic limbs. Patients with thoracolumbar disk disease are more likely to have proprioceptive and motor deficits, requiring greater attention to balancing and strengthening activities. Additional nursing care is required such as bladder management, extending the skills of the veterinary therapist and dictating close interaction between the therapist and veterinarian.

Therapeutic modalities and exercises prescribed depend on the stage of the postoperative period and the neurologic status of the patient. Control of pain and swelling and the beginning of exercise are the focus of the initial postoperative period. Swelling of the surgical site is addressed with cryotherapy. Electrical stimulation is applied for pain relief using interferential or premodulated interferential waveforms. Therapeutic ultrasound must be used with care over the thoracic and lumbar epaxial musculature to avoid generating excess heat over the laminectomy site and possibly damaging nerves and the spinal cord.

Depending on the neurologic deficits, the patient may be unable to sit, stand, ambulate, or urinate independently. Appropriate supportive care, including bladder management, must be carefully performed, and there must be close communication between the therapist and veterinarian. Occasionally patients have significant hyperesthesia along the thoracolumbar areas. In these cases, light massage and desensitization procedures may be useful. Patients with significant paraparesis or paraplegia may benefit from therapeutic exercises designed to help gain trunk control. One exercise is to assist patients to a sitting position with decreasing amounts of support until they are able to sit independently. After this is achieved balance can be challenged using gentle perturbation exercises on firm surfaces initially, and then progressing to unstable surfaces such as an exercise roll, foam mats, bubble wrap, or pillows. It may be helpful for the therapist to be positioned caudal to the patient and place the hands on the cranial stifle to help keep them extended to maintain a weight bearing position. Russian or biphasic ES to the muscles of the pelvic limbs may be used to induce stifle and hock extension and flexion, as tolerated by the patient.

Standing exercises may begin as soon as treatment is initiated. Appropriate support is provided while placing the patient in a standing posture to ensure some loading of the pelvic limbs and correct positioning of the feet. To promote correct stance, support the patient under the chest and pelvis and place the limbs in the correct stance twice daily while the patient is eating. This fosters continued extension of the limbs by proprioceptive neuromuscular facilitation and allows the patient to remain in the standing position for a longer period of time. This can be performed on a firm surface or with the patient supported by an exercise roll. Gently allow the dog to intermittently bear weight. If the patient tends to sink down, tickle the perineal region to stimulate extension of pelvic limbs. After the patient is able to maintain a standing position, pressure is applied to the pelvic limbs by pressing on the dorsal aspect of the pelvis. Gentle perturbations are applied from all angles while the patient is standing so that it is challenged to maintain stability and a standing position. Early ambulation may be assisted by moving the pelvic limbs in a reciprocal walking pattern.

Ambulation is allowed at controlled paces in patients with motor control. Assisted tail or sling walking and underwater treadmill hydrotherapy may be used to unload weight before attaining complete ambulatory independence. Strengthening exercises are initiated as independent ambulation improves (Figures 34-13 through 34-17). Activities include ascending and descending inclines, walking in circles or figure eights, walking on terrain with varying textures (carpet, grass, sand), stepping over objects of varying size to regain proprioceptive awareness, and practicing sit-to-stand activities for coordination. Nonslip flooring is ideal to encourage proprioception and appropriate limb placement. Commercially available booties may provide protection for dogs that tend to knuckle over on the dorsum of the paw or drag the paws while ambulating.