Neurological Emergencies

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NeurologicalEmergencies

• by
• Jerry Demuth

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Seizures
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Forebrain Disease
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(No Transcript)
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Status Epilepticus

• Defined as continuous seizure activity lasting
  for 5 minutes or longer or repeated seizures with
  failure to return to normality within 30 minutes

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Etiology

• Idiopathic (genetic) epilepsy - 28
• Symptomatic epilepsy - 32 to 35
• Reactive epileptic seizures (RES) - 7 to 12
• Unknown - 25 to 28

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Complications

• Increased autonomic discharge
• tachycardia
• hypertension
• hyperglycemia
• Physiologic deterioration
• hypotension
• hypoglycemia
• hyperthermia
• hypoxia

• Metabolic derangements
• lactic acidosis
• hyperkalemia
• hypoxia
• hypercarbia
• hyperthermia
• Severe myoglobinuria

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Emergency Treatment

• Stop the seizure
• Get vascular access as soon as possible
• Systemic stabilization
• Initiate diagnostic workup
• History

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Stop the Seizure(Status epilepticus)

• Diazepam bolus
• 0.5-2.0 mg/kg
• Midazolam
• 0.07-0.22 mg/kg
• Diazepam CRI
• 0.5-2.0 mg/kg/h
• diluted into saline
• light sensitive
• Phenobarbital
• 2-4 mg/kg

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Stop the Seizure(refractory Status Epilepticus)

• Phenobarbital infusion
• 2-4 mg/kg/h
• maximum of 24 mg/kg/24 h
• Propofol
• bolus 2-8 mg/kg to effect
• 6-12 mg/kg/hr infusion
• Pentobarbital
• 2-15 mg/kg to effect
• 1-5 mg/kg/h infusion
• General anesthesia

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Systemic Stabilization

• ABCs
• Airway
• Breathing
• Circulation
• Temperature regulation
• passive cooling
• do not be too aggressive
• Correct derangements

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Traumatic Brain Injury
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Etiology

• Motor vehicle trauma
• Falls
• Animal attacks
• Gun shot wounds
• Malicious injury

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Pathophysiology

• Primary brain injury
• immediate
• direct parenchymal damage
• direct vascular damage
• beyond clinicians control

• Secondary brain injury
• minutes to days
• Extracranial events
• hypovolemia
• hypoxemia
• Intracranial events
• ?sensitivity of cerebrovascular and neuronal
  tissue
• elevation of ICP
• altered cerebrovascular reactivity

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Intracranial Pressure Dynamics

• Intracranial pressure (ICP) is the pressure
  exerted by tissues and fluids within the cranial
  vault
• Cerebral perfusion pressure (CPP) is a primary
  determinant of cerebral blood flow (CBF) and
  hence brain oxygenation and nutritional support.

CPP MABP - ICP
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Intracranial Compliance

• Change in volume per change in pressure
• Maintains ICP within the normal limit of 0-15 mm
  Hg
• Quickly exhausted in TBI
• Acute changes can be fatal

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Initial Assessment

• Do not focus on the patients neurological status
• ABCs first
• Quick assessment testing
• PCV/TS
• Azostix
• Blood glucose
• Blood pressure

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Fluid Therapy

• Hypovolemia and hypoxemia need to be recognized
  and addressed immediately
• Need to achieve normotension
• Do not over-hydrate
• Hetastarch

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Crystalloid Therapy

• LRS, 0.9 NaCl, Normosol
• Administered at shock volumes
• Dog -- 90 mls/kg/hr
• Cat -- 60 ml/kg/hr
• Do not overhydrate
• Never use D5W

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Hypertonic Saline

• Adminster at shock dose of 4 to 5 ml/kg over 3 to
  5 minutes
• Advantages
• improved MABP
• improved CPP
• protects against increased ICP
• The perfect crystalloid?

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Hetastarch

• Administered at a dose of 10 to 20 mL/kg to
  effect
• Advantage Long intravascular half-life

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Oxygen Therapy

• Hyperoxygenation is recommended
• PaO2
• Application
• face mask
• oxygen cage
• nasal catheter at 100 mL/kg/min
• intubation
• tracheotomy

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Mannitol

• Dose 0.5 to 1.0 g/kg i.v. over 10 to 20 minutes
• Repeat up to 3 times in a 24 hour period
• Give through filter
• First-line therapy for ? ICP and improving
  cerebral perfusion pressure

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Furosemide (Lasix)

• Dose 0.7 to 5 mg/kg i.v. several minutes prior
  to mannitol therapy
• May be synergistic with mannitol in ? ICP
• May prevent mild transient rise in ICP associated
  with initial mannitol therapy

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Corticosteroids

• Highly controversial
• NOT recommended at all in head trauma
• Hyperglycemia

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Other Therapy

• Keep head elevated 15 to 30 degrees
• NO jugular sticks
• Control of hyperglycemia
• Other therapies
• Polyethylene glycol (PEG)
• Pentobarbital coma

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Do not give up on these patients!

• The recuperative ability of brain-injured animals
  is tremendous
• Plasticity
• Time

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Modified Glasgow Coma Scale

• Motor Activity
• 6 - Normal gait normal spinal reflexes
• 5 - Hemiparesis tetraparesis
• 4 - Recumbent intermittent extensor rigidity
• 3 - Recumbent constant extensor rigidity
• 2 - Recumbent constant extensor rigidity with
  opisthotonus
• 1 - Recumbent hypotonia of muscles depressed or
  absent spinal reflexes
• Brainstem Reflexes
• 6 - Normal pupillary light responses and
  oculocephalic refexes
• 5 - Slow pupillary light reflexes normal to
  reduced oculocephalic reflexes
• 4 - Bilateral unresponsive miosis normal to
  reduced oculocephalic reflexes
• 3 - Pinpoint pupils reduced to absent
  oculocephalic reflexes
• 2 - Unilateral, unresponsive mydriasis reduced
  to absent oculocephalic reflexes
• 1 - Bilateral, unresponsive mydriasis reduced to
  absent oculocephalic reflexes
• Level of consciousness
• 6 - Occasional periods of alertness and
  responsiveness to the environment
• 5 - Depression or delerium capable of responding
  to the environment
• 4 - Semicomatose responsive to visual stimuli
• 3 - Semicomatose responsive to auditory stimuli

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MGCS Score Evaluation

• The patients score may be an indication of the
  underlying brain injury
• Provides a linear correlation with prognosis (in
  the first 48 hours)

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Spinal Cord Injury
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Acute Spinal Cord Disease

• Extruded intervertebral disc
• Meninitis or meningomyelitis
• Trauma
• Atlantoaxial subluxation

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Evaluation

• Handle very carefully
• Localize the lesion
• Test deep pain perception

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Treatment(Corticosteroids)

• Controversial -- Not recommended
• Polyethylene glycol
• 1 ml/lb i.v. over 30 minutes

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Treatment(Novel treatments)

• Decrease excitotoxicity
• NMDA antagonists
• Calcium antagonists
• Progesterone
• Inhibit lipid peroxidation
• Free radical scavangers
• Support or replace cell membranes
• Polyethylene glycol

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Treatment(Novel treatments)

• Improve spinal cord blood flow
• Opiate receptor antagonists
• Enhance neuronal and axonal repair
• Oscillating field stimulation
• Restore intracellular and extracellular potassium
  concentrations
• Potassium channel blockers

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Need to know...

• Time is of the essence!
• Statistics
• Patients down with conscious movement in the
  limbs (paresis) - surgery is 95 successful
• Patients down with no conscious movement (plegia)
  but still retaining deep pain perception -
  surgery is 90 to 95 successful
• Patients down with no conscious movement (plegia)
  and NO deep pain perception (less than 8 hours) -
  surgery is 50 to 75 successful
• Patients down with no conscious movement (plegia)
  and NO deep pain sensation (over 24 to 48 hours)
  -- surgery is less than 50 successful

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Seizure Disorders
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Four Components

• Prodrome
• Aura
• Ictus
• Post-Ictus

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Etiology

• Idiopathic (Genetic) Epilepsy
• Symptomatic Epilepsy
• Probable Symptomatic Epilepsy
• Reactive Seizures

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Anticonvulsants(First Line)

• Phenobarbital
• T½ - 24 hours
• 2 to 3 mg/kg p.o. q 12 hr
• Potassium Bromide
• T½ - 24 days
• 22 to 30 mg/kg p.o. q 12 to 24 hrs.

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Anticonvulsants(Second Line)

• Zonisamide (Zonegran)
• T½ - 15 to 20 hours
• 8 to 10 mg/kg p.o. q 12 hr
• Felbamate (Felbatol)
• T½ - 24 days
• 15 mg/kg p.o. q 8 hr
• Pregamblin (Lyrica)
• T½ - not published
• 2 mg/kg p.o. q 8 to 12 hr

• Levetiracetam
• T½ - 4 to 6 hours
• 5 to 30 mg/kg p.o. q 8 to 12 hr
• Topiramate
• T½ - 20 to 30 hours
• 2 to 10 mg/kg p.o. q 12 hr
• Gabapentin
• T½ - 2 to 4 hours
• 30 to 60 mg/kg/day
• 100 to 300 mg per dog q 8 hr

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Cost Comparison(Assuming a 30 dog)