Ronaldo C. da Costa & Curtis W. Dewey
Developing a comprehensive list of differential diagnosis is a key step in the diagnostic approach of patients with neurologic prob-lems. This step is dependent on appropriate neurologic local-ization. For example, a dog with an abnormal gait in all four limbs could have a lesion in the cerebellum, brain stem, or cer-vical spinal cord. Obviously, the list of differential diagnoses and the approach for a patient with a cerebellar lesion will be quite different from one with a cervical spinal cord disease. There-fore to appropriately use the tables in this chapter, the clinician should complete a physical and neurologic examination to con-firm that the patient has a neurologic problem and localize the lesion appropriately. When developing a list of differential diag-noses, the patient’s signalment and history often provide impor-tant clues. The goal of this chapter is to bridge the process of localizing a lesion with the selection of the most likely diseases to develop a diagnostic plan. Only the key features of the common diseases will be listed; more detailed information about the dif-ferential diagnoses included herein can be found in other chap-ters. The chapters containing detailed information will be indi-cated in each table.
Diagnostic approach
The approach to patients with neurologic diseases includes a thorough physical and neurologic examination aimed at local-izing the lesion. Proper lesion localization is paramount for the diagnostic approach, as differential diagnoses and ancil-lary diagnostic tests are dependent on proper lesion localization (Fig. 4.1 and Fig. 4.2).
In terms of lesion localization it may be helpful to localize the lesion to “big” regions first and then refine the process by nar-rowing the location to a specific brain or spinal cord region. For example, first establish whether the lesion is in the central (CNS) or peripheral (PNS) nervous system, then, if in the CNS, define whether it is the brain or spinal cord.
The brain can be functionally divided into forebrain (the same as thalamocortex, prosencephalon, or cerebrum), brain
stem (mesencephalon or midbrain, pons and rostral and caudal medulla), and cerebellum. Vestibular signs are a very common manifestation of brain-stem disease. Vestibular disease can be a sign of a brain-stem problem (rostral medullary lesion) com-monly known as central vestibular disease, or an inner ear prob-lem (vestibulocochlear nerve or receptors), known as peripheral vestibular disease.
The spinal cord is divided into four major segments. It is important to remember that the spinal cord segments do not match up with the vertebrae in the cervical and lumbar regions and that there are seven cervical vertebrae but eight cervical spinal cord segments (Fig. 3.16). The main spinal cord divisions in terms of lesion localization are C1 to C5, C6 to T2, T3 to L3 and L4 to S3. In addition to these four classic spinal cord seg-ments, there are three subdivisions that are clinically relevant and may assist the clinician in considering the appropriate dif-ferential diagnoses and select the most indicated ancillary tests.
These subdivisions are the vertebral regions T2 to T10, and L6–
L7–S1.
Finally, we have the neuromuscular diseases in a separate cat-egory. For detailed information on the clinical features seen with lesions in each specific brain, spinal, or neuromuscular region, the reader is referred to the specific chapters (Chapters 7, 13, 17, 18, and 19).
Differential diagnosis
The simplest approach to a case with neurologic signs, once the lesion is localized, is to consider differential diagnoses using the acronym lists based on pathophysiologic mechanisms. These acronyms are called either VITAMIN-D or DAMNIT-V and are very useful and practical ways to approach neurologic dis-eases. A list of common diseases according to the VITAMIN-D acronym is presented in Table 4.1 and Table 4.2, and Fig. 4.1 and Fig. 4.2. When using this acronym, it is useful to consider the signalment and history to develop appropriate differential diag-noses for the patient. For example, even though intervertebral
Practical Guide to Canine and Feline Neurology, Third Edition. Edited by Curtis W. Dewey and Ronaldo C. da Costa.
©2016 John Wiley & Sons, Inc. Published 2016 by John Wiley & Sons, Inc.
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53
imaging. CT=computed tomography. PCR=polymerase chain reaction. CSF=cerebrospinal fluid analysis.
Figure 4.2 Algorithm presenting the differential diagnoses and diagnostic approach to spinal problems according to lesion localization. (The Ohio State University. Reproduced with permission.)
∗indicates nonpainful spinal cord diseases. CSM=cervical spondylomyelopathy. IVDD=intervertebral disc disease. FCEM=fibrocartilaginous embolic myelopathy. MRI=magnetic resonance imaging. CT=computed tomography. PCR=polymerase chain reaction. CSF=cerebrospinal fluid analysis.
Table 4.1 Common brain diseases based on the VITAMIN-D acronym for dogs and cats.
Disease mechanism Specific diseases
Vascular Canine or feline cerebrovascular disease (ischemic or hemorrhagic)∗
Inflammatory/Infectious Meningoencephalitis of unknown etiology
Necrotizing meningoencephalitis Granulomatous meningoencephalitis
Infectious meningoencephalitides (bacterial, fungal, rickettsial, viral [distemper])
Trauma Craniocerebral trauma(head trauma, injury) Traumatic vestibular disease (peripheral)
Toxic Lead poisoning
Metronidazole toxicity
Multiple toxicities cause brain signs (see Chapter 23)
Anomalous Hydrocephalus
Chiari-like malformation and syringomyelia
Quadrigeminal (arachnoid) cysts Cerebellar hypoplasia
Cerebellar abiotrophy Polymicrogyria
Metabolic Hepatic encephalopathy
Hypoglycemic encephalopathy Uremic encephalopathy
Electrolyte-associated encephalopathies Idiopathic Idiopathic epilepsy
Idiopathic vestibular disease
Neoplastic Primary brain tumors
Secondary (metastatic) brain tumors Nutritional Thiamine deficiency
Degenerative Cognitive dysfunction Lysosomal storage diseases Mitochondrial encephalopathies Organic acidurias
∗Bold used to indicate common diseases.
disc disease is the most common spinal disease of dogs, it is not a reasonable differential diagnosis for a 6-mo-old dog with chronic paraparesis. Some generalities should be considered when using the VITAMIN-D acronym. Young dogs are more likely to have congenital or inflammatory conditions. Acute pre-sentations are usually caused by vascular or traumatic condi-tions. Chronic presentations are usually seen with degenera-tive or neoplastic processes. Another way to approach patients with neurologic problems is to develop a list of diseases that are known to affect specific regions of the brain and spine. This is useful mainly for spinal disorders, because although many eases affect several spinal regions (e.g. intervertebral disc dis-ease, discospondylitis, fibrocartilaginous embolic myelopathy), many are region-specific (e.g. atlantoaxial instability, cervical spondylomyelopathy, degenerative myelopathy). The primary differential diagnoses for the most common diseases affecting each region of the brain and spine are presented in Tables 4.3–
4.9. Some of the diseases listed are presented in only one table
Table 4.2 Common spinal diseases based on the VITAMIN-D acronym for dogs and cats.
Disease mechanism Specific diseases
Vascular Fibrocartilaginous embolic myelopathy∗ Epidural hemorrhage
Spinal cord hemorrhage
Inflammatory/Infectious Discospondylitis(bacterial or fungal) Meningitis(steroid-responsive
meningitis-arteritisor bacterial meningitis) Meningomyelitis infectious(bacterial,
fungal, rickettsial, viral) ornoninfectious (unknown etiology, granulomatous meningoencephalomyelitis) Spinal empyema
Vertebral osteomyelitis
Trauma Spinal trauma(fracture/luxations) Traumatic disc extrusion
Traumatic atlantoaxial subluxation
Toxic None
Anomalous Atlantoaxial instability Chiari-like malformation and
syringomyelia Hemivertebra Arachnoid cysts
Multiple cartilaginous exostoses Spinal bifida
Spinal dysraphism
Metabolic None
Idiopathic Disseminated idiopathic skeletal hyperostosis (DISH)
Neoplastic Primary or secondary spinal tumors Nutritional Pathologic fractures due to metabolic bone
disease Hypervitaminosis A (cats) Degenerative Intervertebral disc degeneration
Degenerative myelopathy Degenerative lumbosacral stenosis Degenerative osteoarthritis of articular facets Extradural synovial cysts
Developmental Cervical spondylomyelopathy
∗Bold used to indicate common diseases.
but can affect any region. For example, discospondylitis is more commonly seen in the lumbosacral area, but can affect any ver-tebral region.
Once the list of differential diagnoses is prepared for the patient, the most probable causes should be ruled in or ruled out, based on appropriate diagnostic tests. The diagnostic approach exemplifying the diagnostic tests used to confirm common brain and spinal diseases is presented in Fig. 4.1 and 4.2.
Specific brain regions
Forebrain (thalamocortex, prosencephalon, cerebrum)
Common diseases affecting the forebrain region mainly in small-breed dogs are the meningoencephalitis (any form of
Breeds Age Onset Neurologic deficits Granulomatous
meningoencephalitis (GME) (chapter 7)
Mainly small Terriers, Poodles
Typically middle age and young, but any age
Acute, subacute or chronic
Focal or multifocal Circling, seizures, blindness Common to see vestibular
signs Necrotizing
meningoencephalitis (NME) (Ch 7)
Mainly small Pug, Maltese, Shih-Tzu
Usually young adult Mean age 2 yrs
Acute Seizures are the most common
sign
Circling and central blindness also common
Meningoencephalitis of unknown etiology (MUE) (Ch 7)
Any, mainly small breeds
Any
Young to middle age more common
Acute, subacute or chronic
Focal or multifocal Circling, seizures, blindness Additional signs if involving
other brain regions Infectious
meningoencephalitis (Ch 7)
Depends on infectious agent, but no clear predisposition for most
Any Bacterial diseases are
typically acute or peracute, protracted course with other agents
Focal or multifocal Signs can progress quickly
from focal to multifocal in bacterial
meningoencephalitis Neoplasia (Ch 7) Golden retrievers and
Boxers have a high predisposition Other brachycephalic
and dolichocephalic breeds also affected
Dogs—vast majority over 5 yrs of age (mean age 9 yrs) Cats—typically older,
mean age 12 yrs
Slowly chronic progressive course is typical
Acute presentations are occasionally seen
Signs typically focal, with the majority fairly asymmetrical (circling, unilateral menace, nasal sensation and/or proprioceptive deficits) Behavioral changes very
common
Multifocal presentations can be seen with secondary neoplasia or primary multifocal neoplasia such as gliomatosis cerebri Cerebrovascular
disease (Ch 7)
Any breed but Cavaliers King Charles Spaniels and Greyhounds are overrepresented.
Thalamic infarcts more common in large breeds
Commonly seen in middle-age to older dogs
Peracute or acute nonprogressive presentation onset is typical
Abnormal mentation, asymmetric deficits (circling, postural reactions, menace and nasal sensation)
Head trauma (Chapter 8)
Any Any Peracute or acute
onset
Progression varies with severity of trauma and secondary effects
Mentation changes are common
Severity of trauma can be assessed based on level of consciousness, motor function, and cranial nerves reflexes (PLR and
oculocephalic reflex) Hydrocephalus Mainly small breeds
Chihuahua, Maltese, Yorkshire, Toy Poodle
Typically younger than 6 mos of age
Signs usually present at a young age, and may progress slowly
Behavioral abnormalities, circling, dome-shaped head, open fontanels, seizures Cognitive dysfunction Any breed Elderly dogs (older
than 9 yrs)
Slowly chronic progressive signs
Neurologic deficits (menace, nasal sensation) not expected
Signs are behavioral, such as inattentiveness, pacing, demented behavior, failure to recognize people or places
PLR=pupillary light reflex.
Table 4.4 Differential diagnoses for common diseases affecting the brain stem. These diseases will cause cranial nerve deficits, such as head tilt, facial nerve paresis, or paralysis, changes in the level of consciousness, and postural reaction deficits.
Breeds Age Onset Neurologic deficits
Granulomatous meningoencephalitis (GME) (Chapter 7)
Mainly small Terriers, poodles
Typically middle age and young, but any age
Acute, subacute or chronic
Typically focal involving pons (trigeminal nerve paresis) and medulla (head tilt, nystagmus, facial paralysis)
Necrotizing leukoencephalitis (NLE) (Chapter 7)
Mainly small Yorkshire Terrier,
Maltese, Shih-Tzu, French Bulldog
Usually young adult (mean age 4.5 yrs)
Acute or chronic progressive
Head tilt, circling, mentation changes, facial paresis/paralysis Circling also common
Meningoencephalitis of unknown etiology (MUE) (Chapter 7)
Any, mainly small breeds
Any age, but young to middle age more common
Acute, subacute or chronic
Focal or multifocal
Infectious
meningoencephalitis (Chapter 7)
Any breed Any Bacterial diseases are
typically acute or peracute, protracted course with other agents
Distemper and rickettsial agents (ehrlichiosis and RMSF) are known to frequently cause central vestibular dysfunction Neoplasia (Chapter 7) Golden Retrievers and
Boxers overrepresented Other brachycephalic
and dolichocephalic breeds also affected
Dogs—vast majority over 5 yrs of age (mean age 9 yrs) Cats—typically older
(mean age 12 yrs)
Slowly chronic progressive course is typical
Acute presentations are occasionally seen
Signs typically focal, many affecting cerebellomedullary angle causing a combination of brain-stem (head tilt, atrophy muscles mastication, facial paralysis) and cerebellar signs (hypermetria, tremors) PLR=pupillary light reflex; RMSF=Rocky Mountain spotted fever.
encephalitis), typically the noninfectious meningoencephali-tides (granulomatous meningoencephalitis, necrotizing menin-goencephalitis, or those where a specific diagnosis cannot be reached, so-called meningoencephalitis of unknown etiology).
Neoplasia is also a common disease, mainly in dogs older than 5 yrs of age. Most dogs and cats have primary brain tumors, but secondary (metastatic) brain tumors are also seen. Head trauma can affect dogs of any age and size, and typically leads to forebrain signs in mild to moderate cases. Cerebrovascular dis-ease (CVD) is being recognized more commonly in both dogs and cats. CVD develops as a peracute onset of typically strongly asymmetric signs. Table 4.3 lists the main characteristics of the primary differentials.
Brain stem (mesencephalon, pons, and rostral/caudal medulla)
Most patients with brain-stem signs will have inflammatory or neoplastic diseases. Less frequent diseases affecting the brain stem are metabolic diseases such as hypothyroidism (causing central vestibular disease), nutritional diseases (e.g. thiamine deficiency), or toxic, such as caused by metronidazole toxicity.
Table 4.4 lists the main characteristics of the primary differen-tials for brain-stem diseases.
Cerebellum
Cerebellar disease in young dogs is commonly caused by con-genital diseases such as cerebellar hypoplasia or abiotrophy
(degeneration). Inflammatory diseases also commonly affect the cerebellum. Idiopathic shaker syndrome (steroid respon-sive tremor syndrome, idiopathic cerebellitis, white dog shaker syndrome) is an inflammatory/immune-mediated disease that causes acute onset of tremors. Cerebellar infarcts are common and typically present as an acute, severe, central vestibular dis-ease. Neoplastic diseases can also affect the cerebellum in both young and old dogs. The main differentials are presented in Table 4.5.
Specific spinal regions
C1–C5 spinal cord segments/C1–mid-C5 vertebrae Common diseases affecting the C1–C5 spinal cord segments in small breeds are atlantoaxial subluxation and cervical intervertebral disc disease. Spinal pain is often present with these diseases. Primary differentials for large-breed dogs with C1–C5 lesions are intervertebral disc disease (IVDD), cervi-cal spondylomyelopathy, and spinal neoplasia, mainly menin-giomas. Trauma is also common and affects both small and large breeds. Cervical pain without neurologic deficits affect-ing the C1–C5 regions is usually caused by steroid-responsive meningitis arteritis, cervical intervertebral disc disease, or dis-cospondylitis. More information for the main clinical character-istics of each disease is presented in Table 4.6.
Table 4.5Differential diagnoses for common diseases affecting the cerebellum. These diseases will cause head and whole-body tremor, cerebellar ataxia, hypermetria, intentional tremors, and menace deficits.
Breeds Age Onset Neurologic deficits
Meningoencephalitis of unknown etiology (MUE) (Chapter 7)
Any, mainly small breeds Any
Young to middle age more common
Acute, subacute or chronic
Focal or multifocal
Neosporosis (necrotizing cerebellitis) (Chapter 7 and 12)
Any, but Labrador Retrievers are overrepresented
Adult dogs Slowly chronic
progressive course
Bilateral and symmetrical cerebellar signs (ataxia, head tremors, hypermetria) Corticosteroid responsive
tremor syndrome (idiopathic tremor syndrome, white dog shaker syndrome) (Chapter 12)
Any breed, but approximately 50%
cases in white dogs
Majority younger than 4 yrs
Acute onset High-frequency, low-amplitude generalized tremors involving head, trunk, and limbs May be seen associated with head
tilt Neoplasia (Chapter 7) Golden Retrievers and
Boxers overrepresented Other brachycephalic and dolichocephalic breeds also affected
Typically older dogs and cats Young dogs (1–4 yrs)
can have a neuroectodermal tumor known as medulloblastoma
Slowly chronic progressive course is typical
Acute presentations are occasionally seen
Signs typically focal, causing asymmetric cerebellar signs characterized mainly by cerebellar ataxia, asymmetric hypermetria, with or without brain-stem signs
Cerebrovascular disease (cerebellar infarcts) (Chapter 7)
Any breed but Cavalier King Charles Spaniels and Greyhounds are overrepresented Cerebellar infarcts more
common in large breeds
Commonly seen in middle-age to older dogs
Peracute or acute nonprogressive presentation is typical
Asymmetric cerebellar ataxia, ipsi-or contralateral head tilt, ipsilateral hemiparesis with postural reaction deficits, opisthotonus, nystagmus, ipsilateral menace deficit Intracranial arachnoid cyst
(IAC) (Chapter 7)
Small-breed dogs, mainly brachycephalic Shih Tzu, Maltese, Pug,
Yorkshire Terriers, and Bulldogs appear overrepresented
Young to young adult dogs (mean age 4 yrs)
Acute or chronic onset Most dogs with IAC are clinically normal
Cerebellar signs may be more common with more severe compressions
Cerebellar ataxia, head swaying, nystagmus, and menace deficits were reported
Cerebellar hypoplasia (Chapter 12)
Any breed of dog or cat Genetic in Chow Chow, Irish Setter, Fox Terrier, Airedale Terrier, and Boston Terrier
Young dogs and cats (signs noticed first few weeks of life)
Static signs
Animals can adapt over time and “improve”
Classic cerebellar signs Bilateral and symmetric Cerebellar ataxia with head and
whole-body tremors Hypermetria, menace deficits
C6–T2 spinal cord segments (cervical enlargement) / vertebrae C5–T1
Frequent conditions seen at this region are cervical interver-tebral disc disease in large-and small-breed dogs, and cervical spondylomyelopathy in large- and giant-breed dogs. Neoplasia, discospondylitis, osteomyelitis, trauma, and fibrocartilaginous embolic myelopathy can also occur in this region (Table 4.6).
T3–L3 spinal cord segments/T2–L3 vertebrae Most spinal diseases in dogs and cats affect the T3–L3 spinal segments. Intervertebral disc disease (either extrusion or pro-trusion) is very common in this location. Other common dis-eases are degenerative myelopathy, spinal trauma, neoplasia, and fibrocartilaginous embolic myelopathy. If the lesion is localized to the mid- to cranial thoracic region, between T2 and T10 ver-tebrae (based on the cut-off of the cutaneous trunci reflex and/or spinal pain), then a few diseases can be considered more likely.
It is important to mention that IVDD is rare at this region. The
diseases that are more commonly seen between T2 and T10 are spinal neoplasia, discospondylitis, and hemivertebra. The differ-ential diagnoses for the diseases affecting the T3–L3 spinal cord region are presented in Table 4.7.
L4–S3 spinal cord segments (lumbosacral enlargement)/L4–L5 vertebrae (dogs)
This is a small spinal cord region, and most diseases affecting the T3–L3 spinal cord region can also affect this region (e.g. IVDD, trauma, neoplasia). A disease that frequently affects this specific region is fibrocartilaginous embolic myelopathy. The main fea-tures of diseases affecting this region are shown on Table 4.8.
L6–L7 vertebrae and sacrum in dogs
Problems affecting the caudal lumbar region are very common in large-breed dogs. Spinal diseases affecting this region can appear similar to musculoskeletal disorders, as lameness may be the only clinical sign. The primary differential diagnoses
Table 4.6 Differential diagnoses for common diseases affecting the cervical spine (C1–C5 spinal cord segments and cervical enlargement). These diseases cause proprioceptive ataxia, tetraparesis, and/or neck pain. (All diseases of this chapter are discussed in detail in chapter 13).
Breeds Age Onset Neurologic deficits Spinal pain
Atlantoaxial instability (subluxation)
Mainly toy or small Yorkshire Terriers,
Poodles
Typically younger than 2 yrs
Acute or chronic Common Obvious ataxia and
tetraparesis
Present in the majority of cases
Arachnoid diverticulum (“cyst”)
Rottweilers (cervical region) Pugs (TL region)
Most dogs are young adults. Median age 2.5 yrs. Pugs are older
Chronic progressive signs
Common—various degrees of proprioceptive ataxia and paresis
Uncommon. If noted usually mild on palpation Cervical IVDD
(extrusions)
Any, mainly small Usually older than 2 yrs Acute Typically mild or not present
Severe Cervical IVDD
(protrusion)
Any, mainly large Middle age to old Chronic Mild to moderate Present, but mild to moderate Cervical
spondylomyelopathy (osseous-associated)
Giant breeds Great Danes, Mastiffs
Usually younger than 3–4 yrs
Usually
chronic, but can be acute
Common Obvious ataxia and
tetraparesis
Usually mild. Seen in 50% cases Cervical
spondylomyelopathy (disc-associated)
Large breeds Dobermans,
Weimaraners
Middle age to old dogs Usually
chronic, but can be acute
Common Obvious ataxia and
tetraparesis
Usually mild. Seen in 50–70% cases Fibrocartilaginous
embolic myelopathy (FCEM)
Any
Usually large breeds Any
Commonly middle age
Acute Common. Usually
strongly asymmetric
Absent (after 12–24 hours)
Spinal trauma Any Any Acute Common Common
Steroid-responsive meningitis arteritis (SRMA)
Boxers, Beagles, Berneses, English Pointers, Golden Retrievers
Young
Usually younger than 2 yrs
Acute or subacute Uncommon Severe
for diseases affecting this region are degenerative lumbosacral stenosis, discospondylitis, neoplasia, and extradural synovial cysts. Spinal pain is often a consistent feature of diseases affect-ing the caudal lumbar/lumbosacral spine. The main clinical features of the diseases affecting this region are presented in Table 4.9.
It is important to have a methodical way to approach patients with neurologic problems. Always start by localizing the lesion. The VITAMIN-D system can be used to select the pri-mary pathophysiologic mechanisms causing the patient’s clini-cal signs. Remember that, generally speaking, each mechanism has a typical onset of signs (e.g. acute onset= vascular and
Table 4.7 Differential diagnoses for common diseases affecting the thoracolumbar spine (T3–L3 spinal cord segments). These diseases cause proprioceptive ataxia, paraparesis, or paraplegia, with normal to increased pelvic limb reflexes. (All diseases of this chapter are discussed in detail in chapter 13 and 15).
Breeds Age Onset Neurologic deficits Spinal pain
Degenerative myelopathy
Mainly large German Shepherds,
Boxers, Pembroke Welsh Corgis
Older than 5 yrs Chronic (months) Common Obvious ataxia and
paraparesis
Absent
Fibrocartilaginous embolic
myelopathy (FCEM) Any
Usually large breeds Any
Commonly middle age
Acute Common
Usually strongly asymmetric
Absent (after 12–24 hrs) Hemivertebra Screw-tailed breeds
French Bulldogs, others Young
Usually younger than 1 yr
Chronic Common
Paraparesis and ataxia Rare
IVDD (extrusions) Any, mainly small Usually older than 2 yrs Acute Typically moderate to severe
Moderate to severe IVDD (protrusion) Any, mainly large Middle age to old Chronic Mild to moderate Usually present but
mild
Meningomyelitis Any Any Usually subacute (few
days)
Variable, but signs are often asymmetric
Variable, can wax and wane
Spinal neoplasia Any
Usually large breeds Any
Commonly middle age to older
Chronic or subacute (2–3 days)
Common Variable, but usually
present
Spinal trauma Any Any Acute Common Common
Table 4.8Differential diagnoses for common diseases affecting the lumbosacral (L4–S3) spinal cord segments or L4–5 vertebrae. These diseases cause mild proprioceptive ataxia, paraparesis, or paraplegia, with decreased to absent pelvic limb reflexes. (All diseases of this chapter are discussed in detail in chapter 13 and 15).
Breeds Age Onset Neurologic deficits Spinal pain
Degenerative myelopathy
Mainly large German
Shepherds, Boxers, Pembroke Welsh Corgis
Older than 5 yrs Chronic (months) Ataxia and paraparesis The decreased patellar reflex is
usually a manifestation of a dorsal (sensory)
radiculopathy, and not a LMN sign
Absent
Fibrocartilaginous embolic myelopathy (FCEM)
Any Usually large
breeds
Any
Commonly middle age
Acute Common
Usually strongly asymmetric
Absent (after 12–24 hours) IVDD (extrusions) Any
Mainly small
Usually older than 2 yrs
Acute Typically moderate to severe Moderate to severe IVDD (protrusion) Any
Mainly large
Middle aged to old Chronic Mild to moderate Usually present but
mild
Meningomyelitis Any Any Usually subacute
(few days)
Variable, but signs are often asymmetric
Variable, can wax and wane Spinal neoplasia Any
Usually large breeds
Any
Commonly middle age to older
Chronic or subacute (2–3 days)
Common Variable, but
usually present.
Spinal trauma Any Any Acute Common Common
Table 4.9Differential diagnoses for common diseases affecting the L6–7 vertebrae and sacrum. These diseases may cause paraparesis with or without proprioceptive deficits, but without proprioceptive ataxia because the spinal cord is not affected. Lameness is also frequently observed with asymmetric lesions in this area. (All diseases of this chapter are discussed in detail in chapter 13, 14 and 15).
Breeds Age Onset Neurologic deficits Spinal pain
Lumbosacral stenosis (cauda equina syndrome)
Usually large breeds German Shepherds are
overrepresented
Middle age to old Chronic Typically mild to moderate Can be severe in late
stages
Lameness may be the only sign
Often present, but may only be elicited with deep spinal palpation Spinal neoplasia Any
Usually large breeds
Any
Commonly middle age to older
Chronic or subacute (2–3 days)
Common Variable, but usually
present Discospondylitis Any
Usually large and giant breeds
Any
Commonly young to middle age
Usually acute Usually not present initially Severe pain, sometimes not localizable
Spinal trauma Any Any Acute Common Common
trauma; chronic=degenerative, neoplastic). (Fig. 1.1). Using the acronym VITAMIN-D or the specific tables by lesion local-ization, the clinician may be able to go from a large list of diagnostic possibilities to a shorter list of diagnostic probabil-ities. Further information on each one of the diseases listed in the tables is provided in the specific chapters elsewhere in the book.
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