Neurological Emergencies (PDF download) by mikesanye

VIEWS: 243 PAGES: 30

									Neurologic Emergencies:
 Triage and Treatment




    Edward MacKillop, DVM
      Neurology Resident
North Carolina State University -
College of Veterinary Medicine
                   Overview
Neuroanatomic localization
Seizures
  Classification
  Etiology
  Treatment
Thoracolumbar disk disease
  Clinical signs
  Treatment
  Grading and prognosis
   Neuroanatomic Localization
• Prosencephalon – cerebral hemispheres +
  thalamus/hypothalamus
• Brainstem – midbrain, pons and medulla
• Cerebellum
• C1-5
• C6-T2
• T3-L3
• L4-S3(Cd)
• Diffuse neuromuscular – neuropathy,
  junctionopathy, myopathy
       Seizure Classification
Generalized – excessive and/or
hypersynchronous neuronal activity, loss of
consciousness
  Tonic-clonic – tonic phase (opisthotonos, extensor
  rigidity) followed by clonus (paddling) of limbs
     Salivation, defecation, urination, mydriasis
Partial (focal) – limited spread, +/- loss of
consciousness or disturbed sensorium
  Simple partial – motor activity, no change in
  sensorium
  Complex partial (pyschomotor) - abnormal behavior,
  flybitting, circling/running,
      Seizure Definitions
Aura – beginning of seizure (short): attention
seeking, agitation, hiding
Ictus - seizure
Post-ictal period – depression, blindness,
demented, ataxia, pacing
Cluster seizures – >1 seizure in 24 hours with
interictal recovery
Status epilepticus – continuous seizure > 5
minutes or >1 seizures with incomplete interictal
recovery
         Seizure Mimics
Syncope – activity related, arrhythmia
Vestibular disease – nystagmus,
dysequilibrium
Narcolepsy/cataplexy – atonic, follows
eating or pleasurable activity
         Seizures - Etiology
Extracranial
  Hypoglycemia
  Electrolyte imbalance – hypocalcemia, hypernatremia
  (hyperkalemia, hyponatremia)
  Hepatic encephalopathy
     Congenital portosystemic shunt (PSS)
     Acquired PSS/liver failure
  Uremia
  Intoxication – ethylene glycol, organophosphates,
  amphetamine, methylxanthines, mycotoxins, lead
  Cardiovascular - hypoxia
          Seizures - Etiology
Intracranial
  Anomaly – hydrocephalus, lissencephaly, arachnoid
  cyst
  Vascular – ischemic, hemorrhagic or hypertensive
  Trauma – ICH, sub/epidural hematoma, skull fracture
  Neoplasia
     Primary – meningioma, glioma, choroid plexus papilloma,
     ependymoma
     Secondary – local invasively (nasal ACA), metastatic
     (melanoma, HSA) or systemic (LMA)
  Meningoencephalitis
     Infectious – rickettsial, fungal, protozoal, viral, bacterial,
     parasite migration (cats)
     Immune-mediated – GME, necrotizing encephalidites
  Primary (idiopathic) epilepsy
          Intracranial Signs
Prosencephalic signs – must wait for interictal
recovery
  Menace deficits
  Postural reaction deficits
  Nasal hypalgesia
  Adversive syndrome – cirlcing, head turn
  History of behavior changes
Brainstem signs
  Cranial nerve deficits
  Ataxia/paresis
  Vestibular disease/opisthotonos
  Normal Neurologic Exam?
Structural lesion in a quiet area – olfactory
bulb, frontal lobe
Extracranial cause
Primary epilepsy
                  Treatment
Benzodiazepines – allosteric GABA agonist
  Pharmacokinetics: mean half-time to equilibration w/
  CSF 3.2 minutes, T½ 3.2 hours
  Diazepam or midazolam – 0.5 mg/kg IV, in a pinch:
  cat/toy dog ½ mL, small dog 1 mL, medium dog 2 mL
  large dog 3 mL
    Ex. cat/toy dog ~10 lbs = 4.5 kg
    4.5 kg x 0.5 mg/kg = 2.3 mg
    2.3mg / 5 mg/mL = 0.46 mL
    GIVE TO EFFECT!
  No venous access: 0.5-1 mg/kg per rectum or
  intranasal, 0.5 mg/kg IM midazolam
                Treatment
Phenobarbital – GABA agonist, glutamate
antagonism, Ca2+ channel inhibition
  Pharmacokinetics – onset of action 15-30 minutes,
  T½ ~42-72 hours (97% steady state @ 5 T½)
  Dosing
    Maintenance 2-3 mg/kg
    Loading 12-20 mg/kg
  Therapeutic blood concentration – 15-45 μg/ml
     1 mg/kg dose = 1 μg/ml increase in serum
            Status Epilepticus
Diazepam – 0.5 mg/kg IV or 1 mg/kg PR
(Airway – if apneic intubate, supplement 02 if
hypoventilating)
Venous access
   Electrolytes, Big 4 (BG)
   If hypoglycemic, 1 mL/kg of 50% dextrose IV diluted 1:1 w/ 0.9 %
   NaCl
   SAVE BLOOD: CBC, chemistry profile, ammonia/bile acids,
   Pb/Br level, (insulin:glucose ratio)
Temperature – start cooling if T>105 (DIC if T>107F);
stop cooling 103F
HR/blood pressure – Cushing’s reflex
Phenobarbital – maintenance or load
Status Epilepticus - Refractory
CRI – heavy sedation/light anesthesia
  Diazepam – 0.1-0.5 mg/kg/hr
  Propofol – bolus 2-4 mg/kg (to effect) then 0.05-0.1 mg/kg/min
     MUST monitor ventillation – pulse ox on lip, blood gas 10 minutes
     after starting
  Pentobarbital – 2-4 mg/kg then 2-5 mg/kg/hr
     May need to intubate
     Violent recovery
Mannitol 0.5 g/kg +/- furosemide
Hyperventillation - PaCO2 28-32 mmHg
(Flumazenil – hepatic encephalopathy)
Steroids – 0.5 – 1 mg/kg prednisone, 0.15-0.25 mg/kg
dexamethasone: last ditch effort, may help brain tumor
or encephalitis, may confound diagnosis
    Indications for Emergency
         Neurodiagnostics
Rapidly progressive neurologic disease
Stupor or coma
Unrelenting seizures
Evidence of early herniation
  Miosis mydriasis
  Opisthotonos with extensor rigidity
  Vestibular signs
Cushing’s reflex - hypertension + bradycardia
  Cerebral perfusion pressure (CPP) = mean arterial
  pressure (MAP) – intrcranial pressure (ICP)
  CPP = MAP – ICP reflex bradycardia
Thoracolumbar Intervertebral Disk
           Disease
Spinal Cord Disease Definitions
Paresis – weakness
  Paraparesis – pelvic limb weakness
    Hindlimb paraparesis = redundant
    Posterior paresis = anatomically wrong
Ataxia – incoordination
Ipsilateral – same side
Contralateral – opposite side
“No superficial pain” = hypalgesia
“No deep pain” = analgesia
   Neuroanatomic Dx: T3-L3
Gait – general proprioceptive (spinal) ataxia, paraparesis
or paraplegia
Posture – kyphosis, scoliosis, recumbent
Tone – normal to increased (spastic)
Postural reactions – decreased to absent
Spinal reflexes
   Patellar - normal to increased (brisk, clonic)
   Withdrawal – normal
   Cutaneous trunci – cut off 2 segments caudal to lesion, may be
   normal with caudal lesions
Pelvic limb pain sensation – norm, hypalgesia, analgesia
+/- Schiff-Sherrington phenomenon – extensor rigidity of
thoracic limbs
Differential Diagnosis: Acute T3-L3
             Myelopathy
 Intervertebral disk disease
 Fibrocartilagenous embolism
 Myelitis/diskospondylitis
 Neoplasia – ischemia, hemorrhage, fracture
 Trauma – fracture, (sub)luxation, traumatic disk
 Hematomyelia – coagulopathy,
 thrombocytopenia
 Non-neural
   Aortic thromboembolism
   Bilateral cruciate disease
      Ancillary Diagnostics
Intervertebral disk disease
      Ancillary Diagnostics
Not intervertebral disk disease
Anatomy of a disk




   Courtesy Dr. Richard Jakowski
  Intervertebral Disk Disease
Hansen type I disk herniation – complete tear of annulus
fibrosis with extrusion of calcified nucleus pulposis into
vertebral canal
   Chondrodystrophoid breeds (Dachshund, Corgi, Pekingese)
   May be acute or chronic
Hansen type II disk herniation – disruption or tear of
inner annular fibers with subsequent protrusion of dorsal
annulus into spinal canal
   Large breed dogs
   Chronic myelopathy or pain
Gun-shot or missile disk herniation – acute, concussive
but non-compressive disk extrusion
   Treatment - Conservative
Cage rest – 4-6 weeks of strict rest (23.5
hours/day in a crate)
   Allow tear in annulus to heal
   Does not address material herniated into
  canal
NSAID – control inflammation/pain
associated with herniated disk material
Steroids – no proven benefit, JUST SAY
NO
   Treatment - Conservative
Methylprednisolone sodium succinate
(Solumedrol) - 30 mg/kg IV bolus followed by 5.4
mg/kg/hr for 23 hours
  Attenuates cell membrane lipid peroxidiation
  (independent of GC receptor)
  NASCIS II: Modest improvement in motor function at
  6 months and 1 yr in MPSS group (only if given within
  8 hours of injury)
Recommendation (Neurosurgery March 2002 Supp):
  “Treatment with methylprednisolone…should be
  undertaken with the knowledge that evidence
  suggesting harmful side effects is more common than
  any suggestion of clinical benefit”
Treatment - Surgery
     Treatment - Surgery
Hemilaminectomy
  Neurologic Grade and Prognosis
Neurologic grade                      Conservative                   Decompression
                                      % Success                      % Success
No deficits
                                      100                            97
Ambulatory paraparesis
                                      84                             95
Non-ambulatory
paraparesis
                                      84                             93
Paraplegia
                                      81                             95
Paraplegia with no deep
pain
                                      7                              64
              Adapted from Sharp and Wheeler, Small Animal Spinal Disorders: Diagnosis and
              Surgery 2005
     Indications for Surgery
Failure to respond to conservative
management
  Persistent pain or neurologic deficits
Rapidly progressive neurologic deficits
Paraplegia with no deep pain
       Ascending/Descending
           Myelomalacia
Ascending/descending liquifactive necrosis of
the spinal cord
   5-10% of cases with no deep pain
Ascending cutaneous trunci cut-off
Loss of pelvic limb reflexes
Limp abdomen
Severe back pain, sometimes fever
Horner’s syndrome
Usually fatal
  Respiratory paralysis

								
To top