Spinal cord disease Flashcards
What signs are associated with a lesion in the cervical (C1-C5) spinal cord segment
Normal/increased forelimb and hindlimb reflexes
Ataxia and spastic paresis/paralysis of all four limbs
Decreased conscious proprioception and postural reactions (wheelbarrowing, hopping) in all four limbs
May observe an enlarged bladder that is difficult to express (i.e., upper motor neuron bladder)
Unsual to observe decreased pain perception in limbs as a lesion of this severity would usually cause respiratory failure
What are the clinical signs associated with a lesion of the cervicothoracic (C6-T2) spinal cord segment
Decreased or absent forelimb reflexes with normal or increased hindlimb reflexes
Usually ataxia and flaccid paresis/paralysis in forelimbes and ataxia and spastic paresis/paralysis in hindlimbs
May get muscle atrophy in forelimbs
Decreased conscious proprioception and postural reactions in all four limbs
Decreased cutaneous trunci reflex to the level of the lesion
May observe an enlarged bladder that is difficult to express
May observe decreased pain perception in thoracic limbs only or all four limbs
May observe Horner’s syndrome with lesions at the level of T1-T3
What are the clinical signs associated with a lesion in the thoracolumbar (T3-L3) spinal cord segment
Normal or increased hindlimb reflexes
Ataxia and spastic paresis/paralysis of hindlimbs
May see “crossed-extensor” reflex
Decreased conscious proprioception and decreased hopping in hindlimbs
Decreased cutaneous trunci reflex to the level of the lesion
May observe an enlarged bladder that is difficul to express
May observe decreased pain perception in hindlimbs
May occasionally see a Schiff-Scherington posture if an acute, severe compressive lesion is present (rare)
What are the clinical signs associated with a lesion in the lumbosacral (L4-S3) spinal cord segment
Decreased or absent hindlimb reflexes
Ataxia and flaccid paresis/paralysis of hindlimbs
Weak withdrawal response
Decreased conscious proprioception and hopping in hindlimbs
May have decrease anal tone with resultant fecal incontinence
May observe enlarged bladder that is easy to express (i.e. lower motor neuron bladder)
May have reduced pain sensation in hindlimbs, tail, and perineal region
May see muscle atrophy in hindlimbs
What biological parameter can help differentiate between spinal cord disease and myopathy
Determination of creatinine phosphokinase levels may help differentiate spinal cord disease from a myopathy (especially in the case of suspected aortic thromboembolism)
Explain why MRI is the preferred imaging modality in cats to investigate spinal cord diseases
Since many spinal cord diseases in cats are intramedullary, MRI is the preferred imaging modality
What would be your differentials for spinal cord disease in cats
Degenerative
- storage disease
- neuroaxonal dystrophy
Anomalous
- Sacrocaudal dysgenesis in Manx
- Syringohydromyelia
- spinal arachnoid cysts
- hypoplasia of the odontoid process with secondary atlantoaxial luxation
Neoplastic
- lymphoma
- vertebrall column neoplasia
- meningeal neoplasms
Nutritional
- hypervitaminosis A
- nutritional secondary hyperparathyroidism
- cobalamin deficiency
Inflammatory/infectious
- FIP
- eosinophilic meningomyelitis
- bacterial meningomyelitis
- FIV
- FeLV-associated degenerative myelopathy
Spinal trauma
- road traffic accident
- high rise syndrome
- intervertebral disc disease
Vascular
- ischemic myelopathy
- fibrocartilagenous embolism
What are the most common causes of spinal cord disease
Inflammatory/infectious etiologies are the most common cause of spinal cord disease
- accounting for around one-third of cases
FIP is by far the most common infectious cause of spinal cord disease in the cat (approximately 50%)
- the disease mostly produces multifocal neurological signs
- the cervical region appears to be most commonly affected
What is the most common neoplasia encoutered in cats with spinal cord disease
The most common neoplastic disorder of the spinal cord in cats is lymphoma (around 30-40% of cases of spinal cord cancer)
Paresis/paralysis are the predominant signs
Spinal pain may occur, presumably due to pressure on nerve roots and meninges by the tumor
These signs tend to be rapidly progressive
Many cats do not have evidence of the disease elsewhere
What is a negative prognostic factor for cats suspected of lymphoma
A positive FeLV status is a negative prognostic indicator
How frequent is spinal trauma in cats? what are the main causes of trauma
Spinal trauma is common in cats
The main causes are:
- road traffic accidents
- falls
What are the main location for spinal trauma in cats
Many cats sustain injuries of the lumbar spines (L3-L6)
Another common site is sacrocaudal dislocation due to tail-pull injury that results in dysfunction of the sacral nerves and the cauda equina (particularly the pelvic and pudendal nerves that control urination)
How frequent is intervertebral disc disease in cats
The incidence of intervertebral disc disease is less in cats than it is in dogs
What is Hansen type 1 disc extrusion
This disc herniation occurs with degeneration and rupture of the dorsal annulus fibrosus and acute extrusion of the nucleus puposus into the spinal canal
- recent studies have shown this to be the most common type of disc herniation in cats
What is Hansen type 2 disc protrusion
This type of disc herniation is characterized by bulging of the intervertebral disc without complete rupture of the annulus fibrosus
- it is most commonly seen in older animals
- clinical signs tend to be slowly progressive
What is the typical history and clinical signs of intervertebral disc disease
Often affected cats have no history of trauma
Clinical signs vary depending on the location of the lesion but typically consist of back pain +/- conscious proprioceptive deficits and paresis/paralysis
What are the most common sites for intervertebral disc disease in cats
The most common sites are:
- thoracolumbar intervertebral discs with T11-12 and L4-5 the most commonly reported sites
What are the key features for fibrocartilagenous embolism
Embolic myelopathy is very rare in cats
It is suspected that a small portion of fibrocartilagenous tissue (presumed to be from the intervertebral disc) occludes the vascular supply to the spinal cord
- this results in acute, asymmetric spinal cord ischemia
Typically signs are acute in onset, not painful and are non-progressive
What is the cause of sacrocaudal dysgenesis
The gene(s) responsible for this structural trait has not been identified
- it is autosomal dominant with variable penetrance
- all affected individuals are heterozygotes
- the homozygous genotype for the Manx mutation is fatal in utero
What are the clinical signs associated with sacrocaudal dysgenesis (Manx disease)
These cats may just be tail-less or have a more severe phenotype that may involve the formation of myelodysplasia of the caudal segments of the spine
Clinical signs include:
- urinary and fecal incontinence
- reduced or absent anal tone
- bunny hopping gait or hind limb paresis or paralysis
What are the key features of spinal arachnoid cysts
Spinal arachnoid cysts are diverticula in the meninges that result in the accumulation of CSF
- this can cause external compression of the spinal cord and neurological signs
Clinical signs vary according to the position in the spine but they tend to be gradual in onset
Affected cats are usually young to middle-aged
Diagnosis is made using MRI or CT-myelography
Treatment is via surgical decompression
The outcome is often excellent
What is intervertebral foraminal disc extrusion
Intervertebral foraminal disc extrusion occurs when extruded nucleus pulposus material enters the intervertebral foramen, rather than the vertebral canal
- lameness can be caused by nerve root compression that may be misinterpreted on clinical examination as a primarily musculoskeletal disorder
What is typical with foraminal intervertebral disc extrusion
With foraminal IVDEs, typically only one spinal nerve is affected
Many spinal nerves typically contribute to one peripheral nerve, explaining why it may be uncommon to see paresis or neurological deficits associated with this condition
What is the typical clinical presentation for cervical foraminal extrusionsion
Cervical foraminal extrusions commonly have a normal neurological examination, with cervical hyperesthesia and thoracic limb lameness
What is the pathophysiology of pain associated with intervertebral foraminal disc extrusion
The pathophysiology of pain associated with IFDE is related to both direct mechanical compression and chemical injury
- extruded disc material produces inflammatory mediators leading to nerve root dysfunction
As a consequence, this can lead to persistent neuropathic pain, which may be responsible for the longevity of clinical signs seen in cases
- 85% of cases have a successful outcome with medical management but there is a long wait to be considered free of clinical signs (median 7.5 weeks)
Regarding the clinical presentation of intervertebral foraminal disc extrusion, which is the implication for your diagnosis
Foraminal IVDE should be on the differential list for any cat presenting with acute onset of pelvic limb lamess, even in the absence of obvious neurological deficits or paraspinal hyperesthesia
How can you explain pseudohyperreflexia of the patellar reflex (i.e., reduced flexor withdrawal reflexes with exaggerated patella reflexes)
A lesion located caudal to the L6 spinal cord segment will lead to sciatic nerve involvement but intact femoral nerve function resulting in pseudohyperreflexia of the patellar reflex
Where will you localise the lesion in a cat with normal fore limbs, LMN hind limbs, UMN bladder
Lesion localisation L4-L7
Where will you localise the lesion in a cat with normal fore limbs, normal hind limbs and LMN bladder
Lesion localisation S1-S3
What is spinal shock
Spinal shock:
- occurs immediately after severe spinal cord injury
- causes loss of spinal cord segmental reflexes caudal to the lesion, regardless of the localisation
- cutaneous trunci reflex is helpful with localisation if the lesion is between segments T3-L3
- signs of spinal shock disappear within 24-48h
