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684.e2 Neck Ventroflexion

Neck Ventroflexion
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PHYSICAL EXAM FINDINGS
BASIC INFORMATION
• Neuromuscular weakness: generalized or physical exam, and basic clinical blood tests are
generally sufficient.
Definition localized neck muscle weakness is possible.
A clinical sign; the neck is continuously or Ventroflexion may be episodic or continuous. Differential Diagnosis
intermittently maintained in a flexed position Exercise or stress may induce weakness or Neuromuscular weakness:
due to an inability or unwillingness to extend collapse. Muscle pain may be present. • Metabolic: hypokalemia (most common cause),
the neck dorsally or involuntary muscular • Neck guarding: pain on neck manipula- hypernatremia, hypocalcemia, hypomagnese-
flexion of the neck tion can occur with or without neurologic mia, hypoglycemia, hepatic encephalopathy
abnormalities (ataxia, limb reflex and • Endocrinopathies: hyperaldosteronism,
Epidemiology proprioceptive abnormalities, mental depres- hyperthyroidism, diabetes mellitus
SPECIES, AGE, SEX sion). The patient may resent or resist neck • Junctionopathies: congenital or acquired
• Cats are predominantly affected, but dogs manipulation. myasthenia gravis
may also display neck ventroflexion. • Active flexion: the neck is actively tucked in • Myopathies: Burmese hereditary episodic
• Age and sex vary, depending on the underly- toward the sternum. Increased muscle tone, paralysis/hypokalemic periodic paralysis,
ing cause. ataxia, spastic gait, mydriasis, opisthotonos, Devon rex myopathy, Labrador retriever
stupor, and seizures may be present. hereditary myopathy, immune-mediated poly-
GENETICS, BREED PREDISPOSITION myositis, Toxoplasma or Neospora myositis,
• Burmese cat: hereditary hypokalemic periodic Etiology and Pathophysiology systemic lupus erythematosus
paralysis/polymyopathy (WINK4 mutation) Neuromuscular weakness: • Neuropathies: chronic inflammatory demy-
• Devon rex cat: hereditary myopathy • The dorsal neck muscles fail to extend the elinating polyneuropathy
• Labrador retriever dog: hereditary myopathy neck to lift the head. • Toxic: organophosphates, botulism, tick
• Miniature smooth-haired dachshund, Jack • Cervical ventroflexion is a hallmark of weak- paralysis (Ixodes, Dermacentor), elapid snake
Russell terrier: congenital myasthenia gravis ness in cats due to their lack of a nuchal bite
ligament. Neck guarding:
RISK FACTORS Neck guarding: • Cervical spinal cord diseases: intervertebral
• Hypokalemia (pp. 516 and 1240) • Cervical pain may cause an animal to disc disease, cervical spondylomyelopathy,
• Hyperthyroidism hold the neck in a fixed flexed position to atlantoaxial luxation, spondylitis, spinal
• Kidney disease minimize head and neck movement. ankylosis (hypervitaminosis A, mucopoly-
• Thiamin deficiency Active flexion: saccharidosis), vertebral fractures/tumors/
• Thiamin deficiency results in polioencephalo- infections, ischemic myelopathy
ASSOCIATED DISORDERS malacia with bilateral symmetrical spongiosis, • Meningitis/meningoencephalitis
• Generalized neuromuscular weakness necrosis, and hemorrhage in the brainstem • Polyarthritis
• Megaesophagus nuclei, cerebrum, and cerebellum. Active flexion:
• Thiamin deficiency
Clinical Presentation
DISEASE FORMS/SUBTYPES DIAGNOSIS Initial Database
The clinical signs can be subdivided into three Diagnostic Overview • Complete neurologic exam (p. 1136)
general categories: Neck ventroflexion is a clinical sign, not a diag- • CBC, serum biochemistry profile (include
• Neuromuscular weakness; more common in nosis. The underlying cause must be identified blood glucose, creatinine, creatine kinase,
cats by a systematic diagnostic approach. Because sodium, potassium, calcium), urinalysis
• Neck guarding; more common in dogs the list of potential causes is fairly short, history, • Serum thyroxine levels (cat)
• Active flexion; rare
HISTORY, CHIEF COMPLAINT
Neuromuscular weakness:
• Ventroflexion may be associated with gen-
eralized weakness; reluctance or inability to
walk; stiff, stilted gait; and other signs of
systemic illness. Signs may be transient or
persistent.
Neck guarding:
• Ventroflexion may be associated with mental
depression and ataxia. The neck may be held
in a fixed position, with decreased movement
of the head.
Active flexion:
• Dietary history may reveal an all-meat diet
or a raw fish diet (i.e., thiamine deficiency).
• Gastrointestinal signs, such as inappetence,
ptyalism, vomiting, and weight loss, may
precede neurologic signs. Ventroflexion may
be associated with ataxia, spastic gait, and NECK VENTROFLEXION Seven-year-old, female, spayed domestic shorthair cat with flaccid ventroflexion
+
seizures. of the neck due to severe hypokalemia (serum K = 2.8 mEq/L). (Courtesy Dr. Etienne Côté.)
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