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128.e2 Brachial Plexus Injury

Brachial Plexus Injury
VetBooks.ir Initial Database

○ Thoracic limb monoparesis/monoplegia
BASIC INFORMATION
or bilateral thoracic limb paresis/plegia • Neurologic examination
Definition ○ Proprioceptive deficit of affected limbs • Cutaneous sensory evaluation (cutaneous
Disruption or dysfunction of the nerves and/ ○ Hyporeflexia/areflexia autonomous zones)
or nerve roots of the brachial plexus (C6-T2 ○ Loss of nociception (superficial or deep • Deep pain evaluation
spinal segments) pain sensation) of autonomous zones of
the thoracic limbs Advanced or Confirmatory Testing
Synonyms ■ Evaluation of all thoracic limb • Electrodiagnostic testing: confirms loss of
Brachial plexus avulsion, brachial plexus autonomous zones and all digits may sensory/motor function (not necessary to
neuritis be necessary. achieve diagnosis)
○ Loss of ipsilateral cutaneous trunci reflex ○ Abnormal spontaneous muscle activity
Epidemiology
■ Lateral thoracic nerve injury (C8-T1 ○ Decreased sensory and/or motor nerve
SPECIES, AGE, SEX spinal nerve roots) conduction velocities
More common in dogs than cats; any age or ○ Ipsilateral Horner’s syndrome • Brachial plexus ultrasonography: can be
sex ■ Sympathetic pathway (T1-T3 spinal useful to visualize brachial plexus neoplasm
nerve roots) (not often effective in diagnosing a brachial
RISK FACTORS • Focal thoracic limb muscle atrophy (5-10 plexus injury)
Trauma, autoimmune/antigenic stimulation days after injury) • CT scan or MRI: rules out other compressive
myelopathies or neuropathies (not often
ASSOCIATED DISORDERS Etiology and Pathophysiology effective in diagnosing a brachial plexus
• If traumatic injury sustained • Brachial plexus injury/avulsion: abduction injury); MRI should be performed if evaluat-
○ Systemic shock, head trauma, pneumo- and/or cranial or caudal displacement of the ing for brachial plexus tumor
thorax, +/− Horner’s syndrome, +/− uni- thoracic limbs that results in injury to the • CSF analysis: usually normal
lateral C6-T2 myelopathy nerves or nerve roots of the brachial plexus
• If neoplasia ○ Complete avulsion more common than TREATMENT
○ +/− Horner’s syndrome, +/− unilateral partial avulsion
C6-T2 myelopathy ○ Caudal nerve root avulsion more common Treatment Overview
than cranial nerve root avulsion Conservative medical management is the treat-
Clinical Presentation • Brachial plexus neuritis: idiopathic inflam- ment of choice for traumatic brachial plexus
DISEASE FORMS/SUBTYPES matory response injuries. During this time, physical rehabilitation
Can involve some or all nerves of brachial ○ Theories include antigenic stimulation by aimed at maintaining joint mobility and avoiding
plexus recent vaccination, allergic reaction, or muscle contracture are key, while monitoring
• Brachial plexus trauma: degree of injury diet hypersensitivities (horse meat). for self-mutilation of the affected limbs. The
○ Neurapraxia: transient conduction block • Neoplasia patient should be monitored for at least 6 weeks
to the nerves without anatomic interrup- with regards to return of neurologic function
tion (avulsion) DIAGNOSIS of the limbs. For inflammatory or neoplastic
○ Axonotmesis: partial avulsion of brachial disease, additional therapies can be considered
plexus nerves (disruption of the axon; Diagnostic Overview in conjunction with rehabilitation.
endoneurium, perineurium, epineurium A presumptive diagnosis can usually be made
remain intact) based on an accurate history of recent trauma Acute General Treatment
○ Neurotmesis: complete avulsion of brachial or vaccination/allergy and neurologic examina- • Supportive care/monitoring/resuscitation for
plexus nerves (axon and surrounding tion findings supporting a brachial plexus traumatic injuries
connective tissue) abnormality: lameness or paresis with hypotonia • Prevent self-mutilation or trauma to the
• Brachial plexus neuritis: inflammation of and hyporeflexia of the thoracic limbs, +/− affected limbs:
nerves of brachial plexus ipsilateral Horner’s syndrome, +/− loss of ○ Booties to protect the paw
• Malignant nerve sheath neoplasm (MNSN): ipsilateral cutaneous trunci, and normal pelvic ○ Elizabethan collar to prevent licking and
can be proximal or distal within brachial limbs. Diagnostic workup typically includes chewing
plexus electrodiagnostic testing (electromyography ○ Neuropathic analgesia
and/or nerve conduction velocities), advanced ■ Gabapentin (10 mg/kg PO q 8h): may
HISTORY, CHIEF COMPLAINT imaging, and cerebrospinal fluid (CSF) analysis. prevent paresthesia and self-mutilation
• Onset of thoracic limb lameness, paresis, or These diagnostics can confirm neuroanatomic • Glucocorticoids: might be of benefit for
paralysis (acute or chronic) lesion localization, identify underlying cause, brachial plexus neuritis, although sufficient
• History of trauma and provide vital prognostic information. scientific information to support their use
• History of antigenic stimulation (e.g., recent has not been confirmed.
vaccination, allergic hypersensitivity) Differential Diagnosis
• Neoplasia: soft-tissue sarcoma, lymphoma Chronic Treatment
PHYSICAL EXAM FINDINGS • Intervertebral disc disease (lateralized) • Prevent self-mutilation
Depends on degree of nerves/nerve roots • Musculoskeletal injury: fracture, joint disloca- • Physical rehabilitation: maintain joint mobil-
injured tion, muscle avulsion ity and prevent muscle contracture
Findings include • Neuropathy: rabies encephalomyelitis, acute ○ Target all joints of the affected limbs
• Neurologic deficits of thoracic limbs, normal canine polyradiculoneuritis/coonhound ○ Passive-range-of-motion (PROM) exercises
pelvic limbs paralysis for 10-15 minutes 3-5 times daily

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