Epidemiological and Clinical Studies in Cats with Thoracolumbar Vertebral Fracture and Luxation and Its Management

Spinal trauma is a frequent and important cause of spinal cord dysfunction. Following spinal trauma, neurological dysfunction of varying degrees is caused by haemorrhage, hematoma, medullary edema, compressive lesions and medullary or associated root lacerations (Grasmueck and Steffen, 2006). The consequences of spinal trauma can lead to permanent disability or death in animals depending up on severity and segment of spinal cord injured (Arias et al., 2007).
       
The most common spinal traumatic conditions reported in cats is thoracolumbar vertebral fractures and luxations, mainly caused by high impact external injuries. Neurological signs of spinal cord injuries are usually related to a focal lesion that can be seen on spinal radiographs. However, neurological examination is necessary to make judegment about the severity of the condition and the prognosis. Deep pain perception in affected limbs is the most important prognostic indicator and lack of deep pain perception implies poor prognosis in spinal cord injury (Platt and Olby, 2004).
       
The aim of the treatment in spinal trauma is to relieve compression on spinal cord and prevent secondary damage. Conservative treatments include administration of anti-inflammatory, antioxidants, fusogens, analgesics and restriction of animal movement. Application of external immobilizer is technically not feasible in feline patients and may affect animal welfare. The objective of surgical treatment is to relieve compression by reestablishing normal position of the vertebral canal and the intervertebral foramina and to limit further damage to spinal cord and nerve roots by stabilizing the affected vertebrae (Krauss et al., 2012).

Recovery in spinal patients is greatly dependent on severity of spinal cord injury at the time of primary damage, extent of secondary damage and complications arising from affection in motor, sensory and autonomic function (Bruce et al., 2008). Therefore, the present study was undertaken with the objective of analyzing association of epidemiological aspects, clinical characteristics and clinical outcome of cats with thoracolumbar vertebral fracture and luxations, aiming to help a better clinical approach in patients with this disease condition.

The present study was conducted in 24 cats treated for thoracolumbar vertebral fracture and luxation, for the period between January 2019 and December 2019, at the Department of Veterinary Surgery and Radiology, College of Veterinary Science and Animal Husbandry, OUAT, Bhubaneswar.
       
All the cats were assessed individually. Anamnesis was collected from the animal owner. General clinical examination was performed to identify presence of spinal injury and concomitant non-neurological lesions. Detailed neurological examination included evaluation of ambulatory status, conscious proprioception response, deep pain sensitivity and urinary retention or incontinence. Lateral and ventro-dorsal view radiographs of vertebral column were obtained by placing the cats on right lateral recumbency with limbs in normal position. Site and type of vertebral lesions, vertebral fracture stability and degree of vertebral canal dislocation were assessed from radiographs.  Vertebral fracture stability was assessed by three compartment theory on lateral view spinal radiographs as per Platt (2016) wherein visibility of fractures in spinous process, articular process and/or roof of spinal canal (laminae) of the vertebrae were recorded as dorsal compartment fractures; fractures on dorsal surface of the body (floor of spinal canal) of vertebrae was recorded as middle compartment fractures and fractures in rest of the body was recorded as ventral compartment fractures (Fig 1A). Visibility of fractures in one of the compartment was recorded as stable fracture (Fig 1C and 1D) and visibility of fractures in two or more compartment was recorded as unstable fractures (Fig 1E and 1F). The degree of dislocation of vertebral canal at the site of vertebral lesion was assessed by measuring displacement of vertebral canal between the cranial and caudal segment in lateral view radiographs as described by Bali et al., (2009) (Fig 1B).
 

       
Based on neurological and radiographic observations, site of spinal cord injury was classified according to the affected spinal cord segment as thoracolumbar (T3-L3), Lumbar (L4-L6) and lumbosacral (L7-S3). Degree of neurological dysfunction was then graded according to Mendes and Arias (2012).
 
In thoracolumbar (T3-L3) and lumbar (L4-L6) segments as:
Grade 1: Pain only
Grade 2: Ataxia, conscious proprioceptive deficit and paraparesis
Grade 3: Paraplegia
Grade 4: Paraplegia with urine retention and overflow
Grade 5: Paraplegia, urine retention and overflow and loss of deep pain sensation.
 
In lumbosacral (L7-S3) segments as:
Grade 1: Pain only
Grade 2: Pain and paraparesis
Grade 3: Pain, urinary incontinence, flaccid tail, relaxed sphincters
Grade 4: Pain, flaccid tail, urinary retention
 
       
The cats were treated either surgically or conservatively, based on the clinical examination findings and willingness of the owner for surgical intervention. Surgical treatment was opted in four cats with unstable vertebral fracture having grade 3 neurological dysfunction, one cat with multiple vertebral fracture having grade 3 neurological dysfunction, two cats with unstable vertebral fracture showing grade 4 neurological dysfunction and one cat with overriding of vertebral fracture showing grade 5 neurological dysfunction. All cats with grade 1 and grade 2 neurological dysfunction were treated conservatively. Two cats with grade 3 neurological dysfunction wherein animal owners were not willing for surgical treatment and seven cats with grade 5 neurological dysfunction wherein prognosis was poor were also treated conservatively.
       
Surgical treatment included immobilize of the vertebral lesion by spinal stapling method, involving two vertebrae cranial and two vertebrae caudal to the lesion, as described by Gage (1971). Through dorsal approach, spinous processes were exposed by elevating epaxial muscles. Dislocated vertebral fractures or luxations were reduced under the guidance of fluoroscopy. 1.00 mm diameter Kirschner wire, bent in ‘U’ shape, was placed on either side of the spinous processes and was fixed in position using 22 G orthopaedic wires passing through the holes drilled at the base of spinous processes (Fig 2). Immediate radiographs were obtained to assess vertebral alignment and implant position (Fig 3). Conservative treatment included patient stabilization; intravenous administration of methylpredniso- -lone sodium succinate at the dose of 30mg/kg weight on the day of presentation followed by 15mg/kg body weight every 8 hours for the first 24 hours as anti-inflammatory (Chai et al., 2008); subsequent oral prednisolone at the dose of 5mg/kg body weight twice a day for 3 days followed by once a day for 3 days; intravenous B-complex vitamins and antibiotic ceftriaxone at the dose of 20 mg/kg body weight as supportive medication for five days; strict cage rest on soft bedding; frequently rotation of animal position; regular physical therapy by massaging of muscles, passive range of motion of joints and stimulation of the limb at different regions; urinary bladder expression three to four times per day in cats with neurogenic bladder dysfunction and administration of oral nutritional supplements and probiotics.
 

 

       
Concomitant injuries were treated conservatively without any surgical intervention. The end result took into account of patient survival and recovery on 60^th post- treatment day. Good voluntary mobility and visceral function was considered satisfactory recovery. Signs of recovery with some ataxia, urinary retention or incontinence and weak proprioception was considered recovery with some disabilities. Absence of signs of recovery or deterioration of condition was recorded as unsatisfactory. The epidemiological data and clinical examination findings at the time of presentation were analyzed for frequencies and their association with clinical outcome on 60^th post-treatment was evaluated.

The details of epidemiological data, case history, clinical examination findings, type of treatment and clinical outcome by 60^th post-treatment day is shown in Table 1, 2 and 3.
 

 

 

 
Epidemiology
 
All the 24 cats in study were domestic short haired cats in good body condition were presented with the complaint of acute onset of loss of voluntary mobility in hindlimb after external trauma. Male and female cats were affected equally. Sub-adult (15/24, 62.50%) cats were most affected when compared to juvenile (3/24, 12.50%) and adults (6/24, 25.00%). Body weight ranged from 0.80 kg to 3.6 kg and cats with body weight of 2kg - 3kg (10, 41.67%) were most affected which correlates with size of sub-adult cats. Incidence was more in semi-domicile (13/24, 54.17%) cats followed by domicile (8/24, 37.50%) and non-domicile cats (3/24, 12.5%). Automobile accident (14/24, 58.33%) was major cause of trauma. Other causes were fall from height (6/24, 25.00%) and attack by other animals (4/24, 16.67%). Most of the cases were presented early with 16/24 cats presented within 48 hours of trauma.  Overall, semi-domicile sub-adult male cats were most affected and major cause was automobile accident (7/24, 29.17%). Similar findings were also reported by Lorenz et al., (2011) and Dewey (2014). According to Mendes and Arias (2012), higher frequency of spinal trauma in young male dogs and cats is probably due to the reproductive behavior of these animals.
       
In the present study, Satisfactory outcome was more in males (6/12, 50.00%) than females (2/12, 17.50%). Poor recovery in females was due more number of female cats with greater degree of vertebral canal dislocation with severe neurological dysfunction, which may be attributed to weaker musculature in females. Juveniles (2/3, 66.66%) had better chance of satisfactory recovery followed by sub-adults (6/15, 40.00%), whereas, none of the adult cats showed satisfactory recovery. This indicates satisfactory outcome can be achieved by surgical or conservative treatment in most of the juvenile and sub-adult cats with grade 2 and grade 3 neurological dysfunction. Further, in the present study different causes of spinal trauma did not influence the degree of neurological dysfunction and clinical outcome. All the cats with satisfactory recovery were among cats presented within 48hours after trauma (8/16, 50.00%) that indicates earlier the treatment better the recovery. According to Fehlings and Perrin (2006), spinal cord compression is a potentially reversible form of secondary injury and early spinal cord decompression improve neurological recovery.
 
Concomitant non-neurological lesions
 
Associated injuries are commonly seen in patients with vertebral fracture and luxations with an incidence ranging from 40% to 83% was reported in thoracolumbar vertebral lesions (Weh and Kraus, 2012; Dewey, 2014). In the present study, concomitant lesions were seen in 7/24 cats (29.17%) (Fig 4). However, thoracic trauma that was not apparent at the time presentation in two cats, caused death in the later period and was diagnosed during autopsy.
 

 
Site and type of vertebral lesion
 
Vertebral lesions were recorded between T10 and L7.  Among them L1 and L7 were most affected, followed by T13 and L2 vertebrae. Vertebral fractures were predominant (23/24) with only one cat with luxation in lumbar region. The resulting spinal cord injury was most common in thoracolumbar (T3-L3) segment (17/24, 70.84%), followed by lumbosacral (L4-L6) (5/24, 20.84%) and lumbar (L7-S1) segment (2/24, 8.33%). Cats with lumbosacral spinal cord segment injury showed comparatively better survival and recovery, however, concomitant pelvic fracture resulted in recovery with some disability in two cats including the cat with grade 1 neurological dysfunction. Only 50% of the cats with thoracolumbar or lumbar spinal cord segment injury showed signs of recovery. T12-T13 region is more sensitive to external forces as it is one of the three most mobile segment of spinal column (Cabassu, 2012) and can cause severe spinal cord injury due to the close relationship of the spine to the spinal cord (Weh and Kraus, 2012). Whereas patients with caudal lumbar vertebrae vertebral lesions have better neurological status at presentation as cauda equina is more resistant to compression than the spinal cord (Bruce et al., 2008).
 
Vertebral fracture stability
 
Stable vertebral fractures were recorded in 7 cats (29.17%) with neurological dysfunction of grade 2 and grade 3. One cat had dorsal spinous fracture and other 6 cats had involvement of only ventral compartment. One cat with multiple vertebral fracture was treated surgically. Recovery in stable fracture was excellent with conservative treatment in 5/6 cats and surgical treatment in one cat. Unstable fractures were recorded in 16 cats (66.67%) of which 12 cats had three compartment involvement and five cats had two compartment involvement. Among unstable fractures, recovery was seen in 6/7 cats after surgical treatment and in 2/10 cats after conservative treatment. On plain spinal radiographs, obviously displaced fractures are assumed to be unstable; however, minimally displaced or non-displaced injuries require closer evaluation to select type of treatment (Platt, 2016).
 
Degree of vertebral canal displacement
 
Distribution of cats in the range of 0% to 30% (14 cats) and 70% to 100% (10 cats) of vertebral displacement was noticed. All the cats in the 0% to 30% of displacement had deep pain sensitivity and recovered either fully or partially after the treatment.  Prognosis was grave in the cats with 70% to 100% vertebral displacement, except in animal no. 10 with L7 fracture and dislocation. Lack of severe neurological impairment and presence of nociception despite the initial displacement of more than 100% of the vertebral canal in L7 fracture and dislocation in a cat was also noticed by Paes et al., (2016) as cauda equina is more resistant to compression than the spinal cord. Araujo et al., (2017) reported similar observation on vertebral canal dislocation in dogs with thoracolumbar vertebral fracture and luxation where in most of the dogs were included in the degree of displacement of 0 to 25% and 76 to 100% and also observed that dogs with 0 to 25% displacement and intact nociception had better neurological recovery. It was opined that patients with more than 30% of dislocation might have severe instability in affected vertebrae and surrounding structures resulting in further dislocation before presentation.  Although degree of spinal canal displacement can be considered as one of the parameter for determining prognosis, radiographic evaluation does not replace neurological examination, as radiographs may not demonstrate maximum vertebral displacement at the time of injury (Dewey 2014 ). Thus, nociception, which is the main parameter to indicate the severity of the spinal cord injury, should be evaluated along with radiographic evaluation (Weh and Kraus 2012).
 
Degree of neurological dysfunction
 
Degree of neurological dysfunction varied from Grade 1 to Grade 5. Satisfactory recovery was recorded in 8/24 cats (33.33%) which had intact nociception with grade 2 to grade 3 neurological dysfunction. Recovery with some disability was noticed in 7/24 cats (29.17%) with neurological dysfunction grade 1 to grade 4, where in voluntary ambulation was noticed with ataxia. Recovery with some disability in animal no. 1 and 19, which had good nociception, was related to concurrent pelvic fracture. Three cats (12.50%) with more than 70% vertebral canal dislocation (Grade 5 in TL and Grade 3 in L) with lack of nociception had unsatisfactory recovery, wherein voluntary ambulation or visceral functions did not recovered, regardless of type of treatment. According to Weh and Kraus (2012), loss of nociception is an indicator of severe spinal cord injury with unfavorable prognosis of vertebral fracture and dislocations. Grasmueck and Steffen (2006) also reported that prognosis is poor for functional recovery after fracture or vertebral dislocation with loss of perception of deep pain, however, the authors also observed that some animals have recovered motor and urinary function after prompt treatment and care.
 
Clinical outcome
 
Six cats (25.00%) succumb to death at different time during observation period and post-mortem findings were suggestive of thoracic trauma in 3cats, pneumonia in 2 cats and urinary tract infection in one cat. 18/24 cats (75.00%) survived up to 60^th post treatment day with satisfactory recovery in 8 cats, recovery with some disability in 7 cats and unsatisfactory in 3 cats.  Among cats treated surgically, 7/8 cats (87.50%) survived with satisfactory recovery in 3/7 (42.85%) cats (Fig 5B) and recovery with some disability in 4/7 cats (57.14%) (Fig 6A). Among cats treated conservatively, 11/16 cats (68.75) survived with satisfactory recovery in 5/11 cats (45.45%) (Fig 5A), recovery with some disability in 3/11 cats (27.27%) and unsatisfactory in 3/11 cats (27.27%). Post-operative complications and implant failure was not noticed in any of the cats treated surgically. However, cats with deteriorating conditions, developed pressure ulcers, urine scalding and muscle atrophy (Fig 6B and 6C).  In a study of management of spinal trauma in 69 cats by Besalti et al., (2002), opined that results of conservative and operative treatment is strongly influenced by degree of spinal cord degradation.
 

 

In the present study, thoracolumbar vertebral fractures and luxations in cats were caused by external impact, frequently by automobile accident. Female cats had poor prognosis compared to male cats due to greater displacement of vertebral canal. Sub-adult cats were affected more commonly, however, younger cats had better recovery compared to adults. Satisfactory recovery was seen in among cases presentation within 48 hours after trauma. Concomitant injuries were either fatal or affected overall recovery. Unstable vertebral fractures were predominant vertebral lesions and thoracolumbar spinal cord segment (T3-L3) injury was most common. Results of surgical clinical outcome in unstable vertebral fracture with grade 3 and grade 4 neurological dysfunction was encouraging with recovery in 6/7 cats. Surgical treatment by spinal stapling using Kirschner wire and orthopaedic wire provided adequate stability and immobilization in vertebral lesions in cats.