Non-compressive Nucleus Pulposus Extrusion Research Articles

Clinical presentation, imaging characteristics, and short‐term outcome of eight cats presented with suspected traumatic atlantoaxial hyperflexion

AbstractTraumatic atlantoaxial hyperflexion is considered rare in cats, and only a few case reports have been published. There are other conditions that can result in a peracute onset of neurological signs localized to the cervical spinal cord segments, including acute noncompressive nucleus pulposus extrusion, ischemic myelopathy, or vertebral fractures. Appropriate treatment for these conditions can only be initiated after an accurate diagnosis has been obtained. The aim of this observational, retrospective, single‐center, descriptive case series study was to describe the clinical presentation, imaging characteristics, and short‐term outcome of eight cats presented with suspected traumatic atlantoaxial hyperflexion. Young male healthy domestic shorthair cats were overrepresented (7/8) and typically presented with a peracute, nonprogressive, nonpainful, nonlateralizing C1–C5 myelopathy (tetraplegia or nonambulatory tetraparesis) following a road traffic accident or head trauma. All MRI studies demonstrated a solitary, focal, ill‐defined intramedullary lesion immediately dorsal to the dens of the axis, affecting both grey and white matter. All cats were treated medically. In 50% of the cats, the neurological grade improved at discharge or short‐term follow‐up, 25% of the cats recovered completely, one cat was static at short‐term follow‐up, and one cat was euthanized due to persistent forebrain signs and lack of neurological improvement.

Outcome in paraplegic dogs with or without pain perception due to thoracolumbar fibrocartilaginous embolic myelopathy or acute non-compressive nucleus pulposus extrusion.

Fibrocartilaginous embolic myelopathy (FCEM) and acute non-compressive nucleus pulposus extrusion (ANNPE) are common causes of acute spinal cord injury in dogs. Outcome among paraplegic deep pain positive (DPP) and deep pain negative (DPN) dogs with either condition and factors influencing recovery have not been clearly established. Dogs with thoracolumbar FCEM or ANNPE resulting in paraplegia presenting to university hospitals between 2012 and 2022 were retrospectively included. Diagnosis of FCEM or ANNPE was based on clinical and magnetic resonance imaging findings. Outcome was defined as successful (recovery of independent ambulation) or unsuccessful (non-ambulatory ≥3 months following diagnosis or at the time of death/euthanasia). Logistic regression analysis was performed to investigate associations between clinical or imaging variables and outcome. Thirty-one dogs were included. In total, 14 dogs were initially paraplegic DPP (8 FCEM, 6 ANNPE) and 17 dogs were paraplegic DPN (11 FCEM, 6 ANNPE). Outcome was available for 26 dogs (14 DPP, 12 DPN) with a median follow-up time of 182 days (range 0-2,311) including 2 dogs euthanized at the time of diagnosis; 1 of 12 DPN dogs (8.3%) regained independent ambulation, whereas 9 of 14 DPP dogs (64.3%) regained independent ambulation. DPN dogs had a significantly higher risk of not regaining independent ambulation compared with DPP dogs (OR: 47.40, 95% CI: 2.09-1073.99). No other variables were associated with outcome. While recovery of ambulation was possible, these results confirm that the absence of pain perception is a useful negative prognostic indicator in dogs with severe thoracolumbar FCEM or ANNPE.

Outcome of the Use of Clinical Reasoning Alone in Dogs with Acute Thoracolumbar Myelopathy and/or Pain.

Acute thoracolumbar myelopathy is a common neurological presentation in dogs. Although certain spinal conditions present with characteristic clinical pictures, managing such cases with clinical reasoning alone (i.e., without cross-sectional imaging) has never been explored. The aim of this study was to define the outcome of patients with suspected intervertebral disc extrusion (IVDE), ischaemic myelopathy (IM) or acute non-compressive nucleus pulposus extrusion (ANNPE) that were managed with clinical reasoning alone. The database of the Queen's Veterinary School Hospital (Cambridge) was searched for paraparetic or paraplegic dogs with suspected IVDE or IM/ANNPE that were initially managed medically without undergoing imaging. Clinical presentation and outcome were recorded. If cross-sectional imaging was subsequently performed, information about the final diagnosis was collected and compared with the initially suspected diagnosis. A total of 123 IVDE cases were collected: 81% had a successful outcome with no imaging performed; 16% had IVDE confirmed with imaging and successful outcome with surgery or medical management; and just 3% were found to have an alternative diagnosis or were euthanised without imaging. A total of 16 IM/ANNPE cases were collected: 94% had a successful outcome, and one dog was euthanised. Successful outcomes can be obtained by using clinical reasoning alone in most dogs with suspected IVDE or IM/ANNPE.

Relation of fibrocartilaginous embolism and acute and non-compressive nucleus pulposus extrusion with imaging tests - case report

ABSTRACT Fibrocartilaginous embolism (FCEM) and acute, non-compressive nucleus pulposus extrusion (ANNPE) are non-compressive myelopathies that are difficult to differentiate. The definitive diagnosis is obtained only with histology, but the presumptive diagnosis is made through clinical signs and imaging tests. The aim of this study is to report the imaging tests performed for the diagnosis of a neurological clinical case and discuss the best diagnostic method. After attending the patient, complementary tests were requested. Radiography results showed no change. The computed tomography diagnostic impression indicated distal protrusion between C6-C7, T11-T12, T13-L1 followed by mild spinal cord compression defined by the presence of a ventral hyperattenuating region. Magnetic resonance (RMI), showed a slight T2W hypersignal, well delimited in the gray matter, lateralized to the right, over the cranial third of C7. Concluding that the magnetic resonance is the method that brought more information for the diagnosis, in which the others were not described medullary alterations pertinent to FCEM and ANNPE. With their fair prognosis, the absence of histological diagnosis of these diseases may be a limiting factor in this study and, in relation to the RMI alterations being very similar between FCEM and ANNPE it is not possible to diagnose fully accurately.

Prevalence, clinical presentation and MRI of intervertebral disc herniations in cats.

The aims of this study were to evaluate the prevalence and to describe the clinical and diagnostic imaging features of the different types of feline intervertebral disc herniation (IVDH). Medical records and imaging studies were retrospectively reviewed for cats diagnosed with IVDH between January 2008 and October 2020. Information obtained from the clinical records included signalment, clinical presentation, the presence of spinal hyperaesthesia and neurolocalisation. Diagnostic imaging findings, including type (ie, intervertebral disc extrusion [IVDE], intervertebral disc protrusion [IVDP] or acute non-compressive nucleus pulposus extrusion (ANNPE), site and number of IVDHs, were recorded. The association between breed, age, sex, duration and severity of neurological signs, the presence of spinal pain and MRI features was evaluated. Forty-three cats were included. A total of 50 IVDHs were identified: 39 cats were diagnosed with a single IVDH and four with multiple IVDHs. The most common type of IVDH was ANNPE (n = 22), followed by IVDP (n = 19) and IVDE (n = 9). Neuroanatomical localisation included L4-S3 (n = 19/43), T3-L3 (n = 18/43) and C1-C5 (n = 6/43). Cats with a single IVDH were statistically significantly associated with a diagnosis of ANNPE (P = 0.023) compared with cats with multiple IVDHs affected by IVDP (P = 0.004). Males were more commonly affected by IVDE (P = 0.020) and females by ANNPE (P = 0.020). Cats with IVDP had a longer duration of clinical signs (P <0.001) than cats with ANNPE and demonstrated milder neurological deficits (P = 0.005). IVDEs were statistically significantly associated with spinal hyperaesthesia (P = 0.013), while ANNPEs were not (P = 0.014). ANNPE, IVDP and IVDE are each associated with distinctive clinical scenarios. Thoracolumbar and mid-to-caudal lumbar regions are the most affected, followed by the cranial cervical spine segment.

Influence of Spinal Shock on the Neurorehabilitation of ANNPE Dogs.

Simple SummaryAcute noncompressive nucleus pulposus extrusion (ANNPE) is characterized by a peracute onset of neurological clinical signs. It is based on the spinal cord contusion with possible manifestation of signs compatible with spinal shock. Treatment is conservative and may involve the implementation of physical rehabilitation protocols. Thus, this study intends to contribute to the knowledge surrounding the ANNPE research and to verify if the presence of spinal shock can affect the outcome, as well as recovery time after neurorehabilitation.Acute noncompressive nucleus pulposus extrusion (ANNPE) is related to contusive spinal cord injuries, and dogs usually appear to be exercising vigorously at the time of onset. ANNPE has a characteristic peracute onset of clinical signs during exercise or following trauma, with non-progressive signs during the first 24 h and possibly signs of spinal shock. The main aim was to assess if the presence of spinal shock affects the neurorehabilitation outcomes of ANNPE dogs. This prospective controlled cohort clinical study was conducted at the Arrábida Rehabilitation Center. All of the dogs had T3–L3 injuries and were paraplegic/monoplegic with/without nociception, the study group (n = 14) included dogs with ANNPE spinal shock dogs, and the control group (n = 19) included ANNPE dogs without spinal shock. The study group was also evaluated using a new scale—the Spinal Shock Scale (SSS)—and both groups were under the same intensive neurorehabilitation protocol. Spinal shock was a negative factor for a successful outcome within less time. SSS scores > 4 required additional hospitalization days. The protocol was safe, tolerable, and feasible and accomplished 32% ambulation within 7 days, 29% in 14 days, and 29% in 30 days. The results were better than those obtained in previous studies—94% at 60 days—and 75% of the dogs without nociception recovered ambulation. Long-term follows-ups carried out 4 years later revealed a positive evolution.

Epaxial muscle atrophy is more evident in large dogs with intervertebral disc disease than in dogs with ischaemic myelopathy

Cross-sectional area (CSA) decreases and fat infiltration increases in epaxial muscles of Dachshunds with intervertebral disc disease (IVDD), but less is known about large breed dogs with IVDD. The aim here was to investigate thoracolumbar epaxial muscle CSA and fat infiltration in large breed dogs with compressive IVDD and acute non-compressive nucleus pulposus extrusion (ANNPE) or fibrocartilaginous embolism (FCE).This retrospective study included large breed dogs with MRI-confirmed IVDD (n = 17) and ANNPE or FCE (n = 13). The CSA and fat infiltration of the thoracolumbar M. longissimus and Mm. multifidi were assessed from T1-weighted transverse MR images using Osirix.The CSA was significantly smaller in dogs with compressive IVDD than in dogs with non-compressive ANNPE or FCE for Mm. multifidi (p = 0.015), M. longissimus (p = 0.070), and these two muscles combined (p = 0.016). Fat infiltration in all muscle measurements was significantly higher in dogs with compressive IVDD than in dogs with non-compressive ANNPE or FCE (all P < 0.050). A significant positive correlation existed between age, duration of clinical signs, and fat infiltration, suggesting more fat infiltration in older dogs with more chronic signs.These signs of muscle atrophy are likely caused by denervation and secondary disuse due to chronic spinal cord compression and prolonged duration of clinical signs.

Probable lumbar acute noncompressive nucleus pulposus extrusion: a case report of acute pain caused by a hydrated nucleus pulposus and review of the literature

Abstract Acute noncompressive nucleus pulposus (NP) extrusion has been widely described in veterinary medicine, especially in dogs and cats; however, cases have rarely been reported in humans. We report a rare case of acute pain caused by a hydrated NP. Magnetic resonance imaging revealed an obvious hyperintense signal on T2-weighted images at the L5/S1 segments, while computed tomography imaging and radiography revealed a mildly herniated disc at the L4/5 level and slight lumbar spondylolisthesis at the L5/S1 segments. The operation was performed to confirm the presence of a red and swollen nerve root on the right side of the hydrated L5/S1 segment. The patient's severe pain disappeared, and full recovery was achieved months after surgery. Thus, our case demonstrated a probable lumbar acute noncompressive NP extrusion in humans and reported associated symptoms and imaging characteristics. In such circumstances, surgical management is indicated and may be associated with a good outcome.

Using Deep Learning to Detect Spinal Cord Diseases on Thoracolumbar Magnetic Resonance Images of Dogs.

Deep Learning based Convolutional Neural Networks (CNNs) are the state-of-the-art machine learning technique with medical image data. They have the ability to process large amounts of data and learn image features directly from the raw data. Based on their training, these networks are ultimately able to classify unknown data and make predictions. Magnetic resonance imaging (MRI) is the imaging modality of choice for many spinal cord disorders. Proper interpretation requires time and expertise from radiologists, so there is great interest in using artificial intelligence to more quickly interpret and diagnose medical imaging data. In this study, a CNN was trained and tested using thoracolumbar MR images from 500 dogs. T1- and T2-weighted MR images in sagittal and transverse planes were used. The network was trained with unremarkable images as well as with images showing the following spinal cord pathologies: intervertebral disc extrusion (IVDE), intervertebral disc protrusion (IVDP), fibrocartilaginous embolism (FCE)/acute non-compressive nucleus pulposus extrusion (ANNPE), syringomyelia and neoplasia. 2,693 MR images from 375 dogs were used for network training. The network was tested using 7,695 MR images from 125 dogs. The network performed best in detecting IVDPs on sagittal T1-weighted images, with a sensitivity of 100% and specificity of 95.1%. The network also performed very well in detecting IVDEs, especially on sagittal T2-weighted images, with a sensitivity of 90.8% and specificity of 98.98%. The network detected FCEs and ANNPEs with a sensitivity of 62.22% and a specificity of 97.90% on sagittal T2-weighted images and with a sensitivity of 91% and a specificity of 90% on transverse T2-weighted images. In detecting neoplasms and syringomyelia, the CNN did not perform well because of insufficient training data or because the network had problems differentiating different hyperintensities on T2-weighted images and thus made incorrect predictions. This study has shown that it is possible to train a CNN in terms of recognizing and differentiating various spinal cord pathologies on canine MR images. CNNs therefore have great potential to act as a “second eye” for imagers in the future, providing a faster focus on the altered image area and thus increasing workflow in radiology.

A Retrospective Study of Vertebral Fracture and Luxation in Dogs Presented to University Veterinary Hospital, Universiti Putra Malaysia in 2015 to 2017

To date, there is data paucity on canine vertebral fracture and luxation (VFL) in the local setting. Therefore, it was hypothesized that the geographical location and stray dog population would influence VFL cases in the University Veterinary Hospital, Universiti Putra Malaysia (UVH, UPM). This study aimed to describe the incidence and characteristics of VFL in dogs presented to UVH, UPM. Medical records, including radiographic images of 74 dogs between 2015 to 2017, were reviewed. VFL dominated the spinal cord disease in dogs at 49% (n = 36/74), exceeding intervertebral disc disease (IVDD) and acute non-compressive nucleus pulposus extrusion (ANNPE). Half of VFL cases were contributed by intact male, small breed dogs aged more than one-year-old, with 52% (n = 11/19) of cases caused by vehicular accidents. Almost two-thirds (n = 21/36) of dogs with VFL were outdoor or stray dogs, and the Th3-L3 region was the most susceptible (52%, n = 19/36) for VFL. More than 70% (n = 25/36) of the patients had unstable fractures, highly associated with severity. In conclusion, the occurrence of VFL in UVH, UPM is three times higher than reported in western countries and most likely contributed by a large number of outdoor and stray dogs.

Acute non-compressive nucleus pulposus extrusion in dogs and cats: An overview

Acute non-compressive nucleus pulposus extrusion in dogs and cats: An overview

Diagnostic Imaging in Intervertebral Disc Disease.

Imaging is integral in the diagnosis of canine intervertebral disc disease (IVDD) and in differentiating subtypes of intervertebral disc herniation (IVDH). These include intervertebral disc extrusion (IVDE), intervertebral disc protrusion (IVDP) and more recently recognized forms such as acute non-compressive nucleus pulposus extrusion (ANNPE), hydrated nucleus pulposus extrusion (HNPE), and intradural/intramedullary intervertebral disc extrusion (IIVDE). Many imaging techniques have been described in dogs with roles for survey radiographs, myelography, computed tomography (CT), and magnetic resonance imaging (MRI). Given how common IVDH is in dogs, a thorough understanding of the indications and limitations for each imaging modality to aid in diagnosis, treatment planning and prognosis is essential to successful case management. While radiographs can provide useful information, especially for identifying intervertebral disc degeneration or calcification, there are notable limitations. Myelography addresses some of the constraints of survey radiographs but has largely been supplanted by cross-sectional imaging. Computed tomography with or without myelography and MRI is currently utilized most widely and have become the focus of most contemporary studies on this subject. Novel advanced imaging applications are being explored in dogs but are not yet routinely performed in clinical patients. The following review will provide a comprehensive overview on common imaging modalities reported to aid in the diagnosis of IVDH including IVDE, IVDP, ANNPE, HNPE, and IIVDE. The review focuses primarily on canine IVDH due to its frequency and vast literature as opposed to feline IVDH.

Magnetic Resonance Imaging Findings in 13 Neurologic Pot-Bellied Pigs.

This study reports the magnetic resonance imaging (MRI) findings in 13 pot-bellied pigs presented to our institution with neurological deficits. Nine pigs had abnormal MRI findings (7 with spinal cord localization and 2 with brain localization), with three of them having histopathological confirmation of the diagnoses. MRI diagnoses included a myopathy suspected to be secondary to Erysipelothrix rhusiopathiae, a round cell neoplasia involving the vertebral canal, myelomalacia, a cervical cyst like extradural lesion, pelvic fracture with secondary cauda equina involvement, two cases of fibrocartilaginous embolism or acute non-compressive nucleus pulposus extrusion, multifocal brain infarcts, and a cystic fourth ventricle dilation resulting in obstructive hydrocephalus and syringomyelia. Four pigs had normal MRI studies, with one of them ultimately diagnosed with idiopathic vestibular disease. This retrospective study illustrates the wide variety of diagnoses achieved with MRI of the head or vertebral column in pigs, several of them having never been described in this species. Some of the conditions identified had a good outcome. This justifies using MRI as an ante-mortem diagnostic tool as it can provide relevant information about the prognosis which can significantly influence treatment recommendations. Our findings suggest that MRI should be considered as a valuable imaging modality, when feasible, in pigs with neurological deficits.

Predictors of urinary or fecal incontinence in dogs with thoracolumbar acute non-compressive nucleus pulposus extrusion.

BackgroundUrinary (UI) and fecal (FI) incontinence occur in up to 7.5% and 32% of dogs, respectively, after thoracolumbar acute noncompressive nucleus pulposus extrusion (ANNPE).Hypotheses/ObjectivesTo investigate clinical, diagnostic, and therapeutic predictors of UI and FI in dogs with ANNPE affecting the T3‐L3 spinal cord segments.AnimalsHundred and eighty‐seven dogs with T3‐L3 ANNPE diagnosed based on clinical and MRI findings.MethodsMulticenter retrospective study. Data were obtained from medical records and telephone questionnaires and analyzed by logistic regression.ResultsUI and FI were reported in 17 (9.1%) and 44 (23.5%) dogs, respectively. Paraplegic dogs were 3 times (95% CI = 1.25, 10.87) more likely to develop UI (P = .018) and 4 times (95% CI = 1.94, 12.56) more likely to develop FI (P = .001) compared to nonparaplegic dogs. Dogs with an intramedullary hyperintensity greater than 40% of the cross‐sectional area of the spinal cord at the same level on transverse T2‐weighted MRI images were 4 times more likely to develop UI (95% CI = 1.04, 21.72; P = .045) and FI (95% CI = 1.56, 10.39; P = .004) compared to dogs with smaller lesions. FI was 3 times (95% CI = 1.41, 7.93) more likely in dogs that were not treated with nonsteroidal anti‐inflammatory drugs (NSAIDs) after diagnosis compared to dogs administered NSAIDs (P = .006) and 2 times (95% CI = 1.12, 5.98) more likely in dogs presented with clinical signs compatible with spinal shock compared to dogs without (P = .026).Conclusion and Clinical ImportanceThe identification of clinical, diagnostic, and therapeutic predictors of UI and FI in dogs with T3‐L3 ANNPE can help to approach these autonomic dysfunctions occurring after spinal cord injury.

Clinical reasoning in feline spinal disease: which combination of clinical information is useful?

The aim of this study was to evaluate if a combination of discrete clinical characteristics can be used to identify the most likely differential diagnoses in cats with spinal disease. Two hundred and twenty-one cats referred for further evaluation of spinal disease were included and categorised as follows: non-lymphoid neoplasia (n = 44); intervertebral disc disease (n = 42); fracture/luxation (n = 34); ischaemic myelopathy (n = 22); feline infectious peritonitis virus myelitis (n = 18); lymphoma (n = 16); thoracic vertebral canal stenosis (n = 11); acute non-compressive nucleus pulposus extrusion (n = 11); traumatic spinal cord contusion (n = 8); spinal arachnoid diverticula (n = 7); lumbosacral stenosis (n = 5); and spinal empyema (n = 3). Information retrieved from the medical records included signalment, clinical history and clinical presentation. Univariate analyses of variables (clinical history, breed, age, sex, general physical examination findings, onset, progression, spinal hyperaesthesia, asymmetry, ambulatory status and neuroanatomical location) were performed, and variables were retained in a multivariate logistic regression model if P <0.05. Multivariate logistic regression revealed that intervertebral disc disease most often occurred in middle-aged, purebred cats with a normal general physical examination and an acute onset of painful and progressive clinical signs. Ischaemic myelopathy occurred most often in older cats with a stable or improving, non-painful, lateralising, C6-T2 myelopathy. Spinal fracture/luxation occurred most often in younger cats and resulted most often in a peracute onset, painful, non-ambulatory neurological status. Concurrent systemic abnormalities or abnormal findings detected on general physical examination were significantly associated with feline infectious peritonitis virus myelitis, spinal lymphoma or spinal empyema. This study suggests that using easily identifiable characteristics from the history and clinical examination can assist in obtaining a preliminary differential diagnosis when evaluating cats with spinal disease. This information could aid veterinary practitioners in clinical decision-making.

Transient depression of pelvic limb reflexes in dogs with acute focal thoracolumbar myelopathy.

OBJECTIVE To determine the prevalence of depressed pelvic limb reflexes and changes in those reflexes over time in dogs with acute thoracolumbar myelopathy. DESIGN Prospective study. ANIMALS 34 dogs. PROCEDURES Dogs with acute pelvic limb paralysis caused by acute noncompressive nucleus pulposus extrusion (ANNPE), fibrocartilaginous embolism (FCE), or compressive intervertebral disk herniation (IVDH) within the T3-L3 spinal cord segments were enrolled in the study. Dogs with depressed or absent pelvic limb withdrawal reflexes as determined by 2 examiners were classified as affected and underwent additional testing to rule out multifocal lesions. Pelvic limb reflexes of affected dogs were reassessed every 12 hours until they returned to normal. Neurologic examinations were performed at 4 and 8 weeks after initial examination for some dogs. RESULTS Compressive IVDH, ANNPE, and FCE were diagnosed in 30, 1, and 3 dogs, respectively. Nine (5 with compressive IVDH and all 4 with FCE or ANNPE) of 34 (26%) dogs were classified as affected. Patellar reflexes were depressed in 2 of 9 affected dogs. The median time required for withdrawal reflexes to return to normal was 60 hours (range, 12 to 156 hours). Onset duration of paralysis was negatively associated with the odds of a dog being classified as affected. CONCLUSIONS AND CLINICAL RELEVANCE Results indicated that dogs with focal thoracolumbar spinal cord lesions, especially those with peracute onset of paralysis, can develop transient depression of pelvic limb reflexes. Awareness of this phenomenon is important for veterinarians to accurately localize lesions and develop appropriate diagnostic plans and prognoses.

Magnetic Resonance Imaging Signal Alterations in Paraspinal Muscles in Dogs with Acute Thoracolumbar Intervertebral Disk Extrusion.

Muscle signal alteration detected on MRI is seen in diverse pathologic conditions. We observed signal alterations within the paraspinal muscles in dogs with acute thoracolumbar intervertebral disk extrusion. The aim of this retrospective study was to describe MRI features of paraspinal muscle signal alteration in dogs with acute thoracolumbar intervertebral disk extrusion and to investigate an association of the signal alterations with neurological grade, type and location of intervertebral disk extrusion, degree of spinal cord compression, and presence of epidural hemorrhage. Medical records of dogs undergoing MRI because of thoracolumbar intervertebral disk extrusion between August 2014 and June 2016 were reviewed. MRI was evaluated for SI changes within the paravertebral musculature, their location, extension, affected muscles, contrast enhancement, and signal void in T2* sequences. Intervertebral disk herniation was categorized as acute non-compressive nucleus pulposus extrusion (ANNPE) or compressive intervertebral disk disease. In five patients, muscle biopsies of areas with signal intensity changes were taken during surgery. In total, 103 dogs were enrolled in the study. Paraspinal muscle signal alterations were visible in 37 dogs (36%) affecting the epaxial musculature (n = 17), hypaxial musculature (n = 12), or both (n = 8). All signal alterations were hyperintense on T2-weighted images and iso- or hypointense in T1-weighted images. Signal void in T2* was not observed in any dog. Postcontrast sequences were available in 30 of the 37 dogs and showed enhancement in 45%. There was neither an association with degree of compression nor epidural hemorrhage. Intervertebral disk extrusion caudal to L1 and a higher neurological grade was associated with the presence of muscle changes. Histopathology revealed mild to moderate acute muscle fiber degeneration with edema and necrosis in three of five samples. The MRI, as well as the muscle samples, show rather unspecific changes. The underlying pathomechanism might be related to ischemia or muscle spasm, but also denervation edema may explain the signal alteration.

Acute hydrated non-compressive nucleus pulposus extrusion: what do we know so far?

An acute extrusion of non-degenerated nucleus pulposus material through a tear in the annulus fibrosus can occur after sudden changes of intradiscal pressure and biomechanics; for example, during vigorous exercise,...

Myelographic and low-field magnetic resonance imaging findings in dogs with presumptive acute hydrated non-compressive nucleus pulposus extrusion

MRI is considered gold standard for the diagnosis of presumptive acute hydrated non-compressive nucleus pulposus extrusions (AHNCNPE). This retrospective study describes the myelographic findings in dogs with AHNCNPE diagnosed by...

Outcome comparison in dogs with a presumptive diagnosis of thoracolumbar fibrocartilaginous embolic myelopathy and acute non-compressive nucleus pulposus extrusion

Dogs with fibrocartilaginous embolic myelopathy (FCEM) or acute non-compressive nucleus pulposus extrusion (ANNPE) are reported to have a fair prognosis; however, persistent motor/autonomic deficits are possible. Specific MRI patterns have...