Head: trauma

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Sections available in full article Introduction, Presenting signs, Acute presentation, Sex predisposition, Cost considerations, Special risks (e.g. anesthetic), Pathogenesis, Etiology, Predisposing factors, Pathophysiology, Timecourse (incubation, duration), Diagnosis, Client history, Clinical signs, Diagnostic investigation, Confirmation of diagnosis, Gross autopsy findings, Histopathology findings, Differential diagnosis, Treatment, Initial symptomatic treatment, Standard treatment, Monitoring, Subsequent management, Sequelae, Prognosis, Expected response to treatment, Reasons for treatment failure, Sources, Publications, Vetstream contributor(s),
Contributors Dr Simon Platt BVMS DipACVIM (Neurology) DipECVN MRCVS RCVS Specialist in Veterinary Neurology
Mr David Godfrey BVetMed CertSAD CertSAM DipABVP(Feline practice) CBiol FSB FRCVS
Dr Elisa Mazzaferro MS DVM PhD DipACVECC

Introduction

  • Cause : road traffic accident/hit by car, falls, kicks and gunshot injuries.
  • Signs : head trauma may be evident from visible wounds or from a dysfunction of one of the organs in the head, eg the brain, nose or tongue. Acute onset of neurological signs related to area of brain injury.
  • Treatment : emergency care should be given to establish an airway and to ensure that breathing and circulation are adequate. Decrease intracranial pressure; remove compressive lesions such as hematomas and depressed fractures; treat cerebral edema; treat seizures if they occur.
  • Eye trauma may need urgent treatment to maximize the chances of retaining sight.
  • Prognosis : guarded - depends on neurological status at presentation, response to emergency treatment, as well as presence of concurrent systemic injuries.

Diagnosis

Clinical signs

Do not focus initially on the patient's neurological status as many patients will be in a state of hypovolemic shock following a head injury, which can exacerbate a depressed mentation.

  • Hypovolemia will need to be recognized and addressed immediately.
  • As with all types of acute injury, the "ABCs" (airway, breathing, cardiovascular status) aspects of emergency care are extremely important  Emergency resuscitation  .
  • Assess whole animal for other signs of trauma:
    • Wounds on the skin or in the mouth.
    • Scuffed nails.
    • Loss, or fracture, of teeth.
    • Epistaxis.
    • Subconjunctival hemorrhage.
    • Ear drum rupture.
    • Contusions.
  • Vestibular disease  Vestibular disease   (head tilt, nystagmus and/or abnormal gait) is most commonly central. If peripheral there is usually blood in the external ear canal.
    Localization of the brain damage may be made by evaluating the cranial nerve reflexes on each side.
  • Neurological deficits:
    • Circling to the side of the lesion, ataxia or tetraparesis.
    • Contralateral blindness with normal pupillary light reflexes.
    • Postural deficits.
    • Possible vestibulo-cerebellar signs if trauma to the hind-brain or global ischemia/increased ICP.
    Damage may occur without signs of severe head trauma as a result of hemorrhage  Intracranial hemorrhage  .
  • Other potential traumatic injuries include:
    • Fractures of long bones.
    • Splenic torsions/rupture  Spleen: trauma  .
    • Ruptured ureters  Ureter: trauma  .
Systemic blood pressure
  • Initial hyperdynamic cardiovascular response to severe head trauma,   →     elevations in blood pressure, heart rate, and cardiac output which is sympathetically mediated.
  • Systemic hypertension elicits bradycardia; bradycardia in a stuporous or comatose animal may indicate rising ICP and the necessity for therapeutic intervention  Intracranial pressure measurement  .
    Hypotension is an ominous predictor of poor outcome.
  • The systemic or mean arterial blood pressure (MABP) is a valuable monitoring parameter for the management of head-injured cats because it is closely related to cerebral blood flow and brain perfusion.
  • As MABP decreases to < 50 mm Hg, vasodilatation ensues, and cerebral blood flow decreases and becomes dependent on MABP.
  • Blood pressure can also be checked regularly and easily with the aid of indirect blood pressure monitors.

Patient ventilation

  • Respiratory system dysfunction can be common after traumatic injury.
    Important to distinguish between abnormal ventilation due to pulmonary compromise or brain damage.
  • Objectively assess function with pulse oximetry, capnography and arterial blood gas analysis  Arterial blood sampling  .
  • The most dramatic respiratory abnormality seen following head injury can be neurogenic pulmonary edema (NPO) causing severe dyspnea, tachypnea and hypoxemia.
  • Hyperventilation may be caused by midbrain compression and as such represents a poor prognosis.
  • Apneustic, ataxic and Cheyne-Stokes respirations indicate brain-stem disease.
  • The head injured patient may have also sustained chest trauma which in itself may cause hypoxia, which reinforces the need for thoracic radiographs close to the time of patient admission.

Diagnosis

Differential diagnosis

  • In cases where no external signs of trauma:
    • Poisoning  Poisoning: overview  .
    • Metabolic coma or seizures  Epilepsy: idiopathic  .
    • Coagulopathy  Hemostatic disorders: acquired  (cerebral hemorrhage).
    • Epilepsy  Epilepsy: idiopathic  .
    • Brain herniation.

Sequelae

Prognosis

  • Guarded - severe injuries may require euthanasia.
  • Many animals are remarkably improved within 24 hours of head trauma.
  • A coma scale  Small animal coma score   is used as a guide to determining treatment and prognosis in humans with brain injury.
  • A similar scale has been adapted for use in dogs, however, its role in determining treatment and prognosis is less clear.
  • A common sense approach based upon diligent and repeated assessment of major neurological functions, such as level of consciousness and voluntary movement, is usually most important.
  • If brain herniation occurs , prognosis is grave.
  • Animals which recover from the acute injury may develop post-traumatic epilepsy  Traumatic epilepsy  weeks, or even months, after the injury.
  • Recovery from brain stem injury may be less than complete, and residual signs commonly remain.
  • Recovery from cerebellar injury often occurs in a similar time frame as for supratentorial injury.
  • If the secondary effects of brain injury are controlled, many animals can recover from the primary brain insult associated with trauma.

Expected response to treatment

  • Improving neurological signs.
  • Cats with concussion would usually be improving by the time that they reached the surgery.
  • In general, clinical signs of unilateral supratentorial injury improve within the first two weeks following trauma.
  • Usually the animal is ambulatory by 4 weeks post-injury, although, residual paresis and blindness may continue.
  • A tendency to circle may also persist. This is especially prominent when the animal is distressed or excited.

Reasons for treatment failure

  • Trauma too severe.

Sources

Publications

Refereed papers

  • Recent references fromPubMed.
  • Bar-Am Y, Pollard R E, Kass P H & Verstraete F J M (2008)The diagnostic yield of conventional radiographs and computed tomography in dogs and cats with maxillofacial trauma.Vet Surg37, 294-299PubMed.
  • Platt S R, Abramson C J, Garosi L S (2005)Administering corticosteroids in neurologic diseases.Vet Clin North Am Small Anim Pract27,210-220.
  • Syring R A (2005)Assessment and treatment of central nervous system abnormalities in the emergency patient.Vet Clin North Am Small Anim Pract27, 343-358PubMed.
  • Gordon P N, Dunphy E, Mann F A (2003)A traumatic emergency: handling patients with head injuries.Vet Med98, 788-798.
  • Syring R S, Otto C M, Drobatz K J (2001)Hyperglycemia in dogs and cats with head trauma: 122 cases (1997-1999).JAVMA218, 1124-1129PubMed.
  • Dewey C W (2000)Emergency management of the head trauma patient.Vet Clin North Am: Sm Anim Pract30, 207-225.
  • Ghajar J (2000)Traumatic brain injury.Lancet356, 923-929.
  • Proulx J & Dhupa N (1998)Severe brain injury - Part 1, Pathophysiology.Comp Cont Ed Pract Vet20, 897-905.
  • Proulx J & Dhupa N (1998)Severe brain injury - Part 2, Therapy.Comp Cont Ed Pract Vet20, 993-1005.
  • Hopkins A L (1996)Head trauma.Vet Clin N A26, 875-891.
  • Dewey C W, Budsberg S C & Oliver J E (1992)Principles of head trauma management in dogs and cats - Part 1.Comp Cont Ed Pract Vet14, 199-207.
  • Rudy R L & Boudrieau R J (1992)Maxillofacial and mandibular fractures.Vet Med Surg7, 3-20.
  • Kapatkin A & Matthiesen D T (1991)Feline high-rise syndrome.Comp Cont Ed Pract Vet13, 1389-1397.

Other sources of information

  • Shores A (1983)Craniocerebral trauma.In: Current Vet Therapy X: Small Anim Pract. W B Saunders. pp847-854.

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