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The neurological examination

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Abstract

The neurological evaluation of a patient aims to determine the anatomical diagnosis (location and distribution of the lesion within the nervous system) together with the patient’s signalment and history in order to determine the differential diagnosis. Disease severity can help the clinician to determine the eventual prognosis of the conditions considered in the differential diagnosis. This chapter looks at history, general physical examination, neurological examination, part I: hands-off examination, part II: hands-on examination. This chapter includes 28 video clips.

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Figures

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1.2 Comprehensive neurological examination form. Cranial nerves: H = horizontal; L = large; M = mid-range; R = rotary; S = small; V = vertical.
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1.5 Head pressing in a 9-year-old neutered Staffordshire Bull Terrier bitch with a thalamic brain tumour.
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1.6 Severe head tilt in a 3-year-old neutered Japanese Chin bitch with a vestibular syndrome caused by granulomatous meningoencephalitis.
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1.7 Right-sided head and body turn (pleurothotonus) in a 10-year-old male Staffordshire Bull Terrier with a right-sided forebrain tumour.
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1.8 Low head carriage and severe neck pain caused by cervical intervertebral disc herniation in a 6-year-old neutered mixed-breed bitch.
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1.9 Decerebrate rigidity in a 4-year-old male French Bulldog with caudal subtentorial brain herniation associated with a large frontal lobe brain tumour.
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1.10 Schiff–Sherrington posture. (Courtesy of S Platt)
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1.13 The menace response is elicited by making a threatening gesture at the eye. The afferent pathway is in the retina, optic nerve, contralateral optic tract and visual cortex. The efferent pathway involves the contralateral motor cortex, the ipsilateral cerebellar cortex and the facial nerve (CN VII). The expected response is closure of the eyelid. The contralateral eye must be blindfolded with the other hand to assess each eye separately. Care must be taken not to touch the eyelashes or to create air currents that might stimulate sensation of the face (CN V, trigeminal nerve) and elicit a palpebral or corneal reflex.
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1.14 Ventral aspect of the skull and cranial nerves that exit the various foramina after leaving the brainstem. Illustration created by Allison L. Wright, MS, CMI, Athens, Georgia, USA.
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1.15 Pupil symmetry can be assessed using the indirect ophthalmoscope. The animal should be examined in room light as well as in darkness to evaluate the ability of the pupils to constrict (parasympathetic function) and to dilate (sympathetic function), respectively.
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1.16 Lateral strabismus in an 8-year-old neutered Rottweiler bitch with a cavernous sinus meningioma. The compression of the oculomotor nerve (CN III) by this tumour is causing paralysis of the medial, dorsal and ventral recti and ventral oblique muscles. The result is a lateral deviation of the eyeball. The eyeball failed to adduct when testing the normal physiological nystagmus. Compared with a vestibular strabismus (which depends on head position), this type of strabismus is visible whatever the position of the head.
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1.17 Assessing the resistance of the jaw on opening of the mouth (jaw tone) tests the motor function of the trigeminal nerve (CN V).
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1.18 Touching the medial or lateral canthus of the eye and observing for a blink test (the palpebral reflex). The afferent arm of this reflex is mediated by the trigeminal nerve (CN V; facial sensation) whilst the efferent arm is mediated by the facial nerve (CN VII; closure of the eyelid).
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1.19 The response to stimulation of the nasal mucosa is a cortically mediated withdrawal of the head. The afferent arm is mediated by the trigeminal nerve (CN V). The integration of this response occurs in the contralateral forebrain. Both sides should be carefully assessed to evaluate possible asymmetry.
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1.20 Observing a curl of the lip as it is pinched indicates that the afferent arm (CN V – trigeminal nerve) and efferent arm (CN VII – facial nerve) of this reflex are intact. Depending on the intensity of the stimulation, a behavioural response (vocalization, turning of the head) may also be observed (cortically mediated response). Both sides must be assessed to evaluate possible asymmetry. Occasionally, decreased perception of facial sensation (hypoalgesia) can be observed in animals with contralateral forebrain disease. In such cases, the animal curls its lip (normal reflex arc) but fails to show a behavioural response after stimulation of the lip contralateral to the lesion (abnormal response).
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1.21 Unilateral temporalis and masseter muscle atrophy in a 9-year-old male Labrador with a trigeminal nerve sheath tumour. The ipsilateral enophthalmia is caused by loss of the temporalis muscle bulk and therefore passive retraction of the eyeball.
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1.22 Dropped jaw and inability to close the mouth in a 5-year-old neutered Cocker Spaniel bitch with idiopathic trigeminal neuritis.
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1.23 Facial asymmetry with drooping of the ear, drooping of the lip and deviation of the nostril to the unaffected side in a 7-year-old male Labrador with acute idiopathic facial nerve (CN VII) paralysis.
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1.24 Vestibular eye movements are triggered by movement of the head in a lateral direction. The eye movements are seen to be slower than the head movement, but the eyes eventually return to the centre of the palpebral fissure. Illustration created by Allison L. Wright, MS, CMI, Athens, Georgia, USA.
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1.25 Placing an animal in dorsal recumbency can help detect a positional nystagmus or strabismus by ‘challenging’ the vestibular system.
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1.26 Ventrolateral positional strabismus in a Rottweiller with a central vestibular syndrome. This strabismus was only visible when the head was placed in a certain position, indicating a sensory dysfunction (vestibular apparatus) rather than a motor dysfunction (CN III – oculomotor disorder).
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1.27 The swallowing reflex can be elicited by applying gentle pressure on the hyoid bones and thyroid cartilage.
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1.28 Deviation and atrophy of the tongue caused by a left-sided hypoglossal nerve paralysis. (Courtesy of S Platt)
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1.29 Proprioceptive positioning response in the pelvic limb. Note: it is important to support the bodyweight of the animal (as shown). Illustration created by Allison L. Wright, MS, CMI, Athens, Georgia, USA.
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1.30 Changing paw position evaluates the conscious awareness of limb position by the animal (proprioceptive placement function). This cortically mediated response is elicited by gently placing the dorsal surface of the foot of the animal on the floor. Care should be taken to support the animal’s bodyweight. The animal should immediately replace its foot in a normal position.
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1.31 The hopping response is tested in the left thoracic limb of this dog. The right thoracic limb is held off the ground and the hind end is supported to put the majority of the bodyweight on the left thoracic limb. The dog is then pushed to the left.
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1.34 Extensor carpi radialis reflex is tested by hitting the proximal region of the antebrachium and observing a slight extension of the carpus.
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1.35 Withdrawal (flexor) reflex. When a noxious stimulus is applied to a digit, the limb should be withdrawn towards the body. Sensory input enters the spinal cord through the dorsal root to activate ipsilateral flexor motor neurons via interneurons and simultaneously inhibit the antagonistic extensor muscles. Contralateral stimulation of extensor muscles is inhibited by the descending UMN influence on the contralateral LMNs. Illustration created by Allison L. Wright, MS, CMI, Athens, Georgia, USA.
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1.36 A normal withdrawal (flexor) reflex in the pelvic limb implies flexion of the hock, stifle and hip. Whilst the withdrawal is evoked, the contralateral limb should be observed for reflex extension (crossed-extensor reflex).
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1.37 Myotatic (stretch) reflex. Striking the patellar ligament stretches (indirectly) the muscle spindles within the quadriceps muscle, which activates the 1A afferent fibres. The sensory fibres synapse directly on to motor neurons to the quadriceps femoris. Illustration created by Allison L. Wright, MS, CMI, Athens, Georgia, USA.
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1.38 The patellar reflex is elicited by hitting the patellar ligament and observing a reflex extension of the stifle joint.
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1.39 The cranial tibial reflex is elicited by hitting the proximal part of the cranial tibial muscle and observing a reflex flexion of the tarsus.
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1.40 The perineal reflex consists of clamping the tail and contraction of the anal sphincter as a result of stimulation of the perineum.
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1.42 The cutaneous trunci (panniculus) reflex is elicited by pinching the skin over the lumbar spine with forceps. It should be tested from caudal to cranial on each side of the spine, starting at the level of the wings of ilium. Bilateral contraction of the cutaneous trunci muscle indicates a normal reflex. In the absence of muscle contraction, the point of skin stimulation should be moved cranially until a normal reflex is observed.
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1.43 Nociception is tested by pinching the digits with fingers or haemostats. Only a behavioural response to the noxious stimulus (turning of the head, vocalization or attempting to bite) indicates conscious pain perception. If no response is elicited when using fingers, the test should be repeated with haemostats to ensure that the response is absent.
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1.44 The spine can be palpated whilst the animal is standing or recumbent. Spinal hyperaesthesia is detected by applying gentle pressure on the dorsal spinal processes and transverse processes of the spine. Simultaneous palpation of the abdomen can help to detect the focus of hyperpathia.
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1.45 Gently manipulating the neck in dorsal, lateral and ventral flexion can help to detect pain and a reduced range of movement.

Supplements

Bilateral vestibular disease

This clip shows a cat with bilateral vestibular syndrome. A wide excursion of the head is seen from side to side in combination with falling to both sides. This cat had bilateral otitis media/interna. (See page 16 in the Manual)

Cerebellar ataxia

This clip shows a dog with cerebellar ataxia. Note the marked hypermetric gait in all four limbs as well as head incoordination. It is important to note that this dog is not showing any signs of paresis, which is consistent with generalized truncal and head ataxia as a result of a cerebellar lesion. (See page 7 in the Manual)

Corneal reflex

The corneal reflex is elicited by touching the cornea and observing for closure of the eyelids. The afferent arm of this reflex is mediated by the corneal branch of the trigeminal nerve (CN V; corneal sensation), whilst the efferent arm is mediated by the facial nerve (CN VII; closure of the eyelid). (See pages 12, 13 and 14 in the Manual)

Cranial tibial reflex

The cranial tibial reflex is elicited by hitting the proximal cranial tibial muscle and observing a reflex flexion of the tarsus. This reflex evaluates the integrity of spinal cord segments L6–S1 and associated nerve roots, as well as the peroneal peripheral nerve. (See page 22 in the Manual)

Cutaneous trunci reflex

The cutaneous trunci reflex is elicited by pinching the skin over the lumbar spine with forceps. It is tested from caudal to cranial on each side of the spine, starting at the level of the wings of ilium and continuing cranially to the level of T2. Bilateral contraction of the cutaneous trunci muscle indicates a normal reflex. (See page 23 in the Manual)

Dysmetria

This clip shows the ‘two-engine gait’ seen with caudal cervical spinal cord lesions. The gait reveals hypometria in the thoracic limbs and hypermetria in the pelvic limbs. This dog has disc-associated cervical spondylomyelopathy at C6–C7. (See page 7 in the Manual)

Extensor postural thrusting

Extensor postural thrusting is tested by lifting the thoracic limbs off the ground and then lowering the pelvic limbs toward the floor, observing for extension of these limbs and backward steps on touching the surface. (See page 18 in the Manual)

Gag/swallow reflex

The gag/swallow reflex is elicited by applying external pressure to the hyoid bones to stimulate swallowing or by stimulating the pharynx with a finger. It assess the integrity of the glossopharyngeal (CN IX) and vagus (CN X) nerves. (See page 16 in the Manual)

Gastrocnemius reflex

The gastrocnemius reflex is elicited by placing a finger over the gastrocnemius muscle and striking it with a reflex hammer. The normal reaction is extension of the hock. This reflex tests the integrity of spinal cord segments L7–S1 and associated nerve roots, as well as the tibial peripheral nerve. (See page 22 in the Manual)

General proprioceptive ataxia

Cavalier King Charles Spaniel showing general proprioceptive ataxia and upper motor neuron (UMN) paresis in both pelvic limbs as a result of intervertebral disc herniation at T12–T13. (See page 7 in the Manual)

Hemi-walking

Hemi-walking tests the ability of the animal to walk on the thoracic and pelvic limbs on one side whilst holding the limbs on the other side. The animal should be pushed away from the side on which its limbs are supported. The speed and coordination of the movements should be assessed. (See pages 17 and 18 in the Manual)

Hopping

The hopping response is tested by holding the contralateral limb off the ground and supporting the hind end of the animal (or front end if testing a pelvic limb) to put the majority of the bodyweight on the limb being tested. The animal is then pushed laterally on the side of the limb being tested. The normal response is hopping on the limb being tested to accommodate a new body position as the centre of gravity is displaced laterally. An equal response should be seen on both sides. (See page 18 in the Manual)

Lip pinch

This reflex is tested by pinching the lip and observing lip contracture. Both sides must be assessed to evaluate possible asymmetry. The afferent arm of this reflex involves the trigeminal nerve (CN V), whilst the efferent arm involves the facial nerve (CN VII). (See page 12 in the Manual)

Menace response

A mixed-breed dog is seen to have increased extensor tone in all limbs following stimulation. There is no change in mentation seen with this extensor rigidity, indicating normal brain function and is more compatible with a neuromuscular lesion. (See page 8 in the Manual)

Myotonia

A mixed-breed dog is seen to have increased extensor tone in all limbs following stimulation. There is no change in mentation seen with this extensor rigidity, indicating normal brain function and is more compatible with a neuromuscular lesion. (See page 8 in the Manual)

Nasal stimulation

The response to nasal stimulation is a cortically mediated withdrawal of the head. The afferent arm of this reflex is mediated by the trigeminal nerve (CN V). The integration of this response occurs in the contralateral forebrain. Both sides should be carefully assessed to evaluate possible asymmetry. (See page 12 in the Manual)

Nociception response

Deep pain perception (nociception) is tested by pinching the digits with the fingers or haemostats. A behavioural response to this noxious stimulus (turning of the head, vocalization, attempting to bite) is considered as evidence of conscious pain perception. (See page 23 in the Manual)

Palpebral reflex

The palpebral is elicited by touching the medial or lateral canthus of the eye and observing for closure of the eyelids. The afferent arm of this reflex is mediated by the trigeminal nerve (CN V; facial stimulation), whilst the efferent arm is mediated by the facial nerve (CN VII; closure of the eyelids). (See page 12 in the Manual)

Paradoxical vestibular disease

This clip shows a dog with hypermetria in the right thoracic and pelvic limbs with no evidence of paresis. A subtle left-sided head tilt is visible. This combination of clinical signs is suggestive of a central vestibular syndrome on the right side, causing a paradoxical head tilt. A mass lesion was found in the right cerebellar-medullary angle. (See page 15 in the Manual)

Patellar reflex

The patellar reflex is performed with the animal placed lateral recumbency and the stifle slightly flexed. The tested limb is supported by placing one hand under the thigh. The reflex is elicited by hitting the patellar ligament with a reflex hammer and observing an extension of the stifle joint (reflex contraction of the quadriceps femoris muscle). This reflex evaluates the integrity of spinal cord segments L4–L6 and associated nerve roots, as well as the femoral nerve. (See page 21 in the Manual)

Perineal reflex

The perineal reflex is elicited by stimulating the perineum with a haemostat, which causes a reflex contraction of the anal sphincter and flexion of the tail. This reflex tests the integrity of the caudal nerves of the tail, the pudental nerve, spinal cord segments S1–Cd5 and associated nerve roots. (See page 22 in the Manual)

Physiological nystagmus

A physiological nystagmus can be induced by moving the head from side to side. The nystagmus is always observed in the plane of rotation of the head and consists of a slow phase away from the direction of the head and a fast phase in the same direction as the head rotation. (See pages 10, 11, 13 and 15 in the Manual)

Proprioceptive placing

Proprioceptive placing of each limb is performed individually. It is essential to fully support the animal and turn the digits of the limb over on to the cranial surface. An immediate response of turning the paw back over and placing the foot on to the floor is considered normal. An absent or delayed response, or a partial return of the digits back to a normal position, is considered abnormal. (See pages 17 and 18 in the Manual)

Pupillary light reflex

The pupillary light reflex (PLR) is tested by shining a bright light into the pupil and assessing for pupillary constriction (direct reflex). The opposite pupil should constrict at the same time (consensual or indirect reflex). A slight dilation usually follows the initial pupillary constriction (pupillary escape) as a consequence of light adaption of photoreceptors. (See page 10 in the Manual)

Vestibular ataxia

This dog has a left-sided head tilt and is leaning/falling to the left. This is consistent with a vestibular ataxia. (See page 7 in the Manual)

Wheelbarrowing

This is a postural reaction test of the forelimbs. It is performed with the neck extended and the pelvic limbs elevated from the ground (with the animal supported under the abdomen). The animal is then forced to walk forwards. (See page 18 in the Manual)

Withdrawal reflex: pelvic limb

The withdrawal reflex is tested by pinching the nail bed or digit of the pelvic limb with fingers or haemostats. The stimulus causes a reflex contraction of the flexor muscles and withdrawal of the limb being tested. A normal withdrawal reflex implies flexion of the hock, stifle and hip. Whilst the withdrawal reflex is evoked, the contralateral limb should be observed for reflex extension. (See page 20 in the Manual)

Withdrawal reflex: thoracic limb

The withdrawal reflex is tested by pinching the nail bed or digit of the thoracic limb with fingers or haemostats. The stimulus causes a reflex contraction of the flexor muscles and withdrawal of the limb being tested. A normal withdrawal reflex implies flexion of the carpus, elbow and shoulder. (See page 19 in the Manual)

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