Neurology: Technician's role in the management of the head and spinal trauma Patient (Proceedings)

Initial evaluation –

If the owner calls your clinic first, and states that the animal is recumbent, instruct them to transport the animal on a plywood stretcher or similar firm support system if at all possible. This is to avoid further damage to the spinal cord if spinal fractures also exist.

Upon arrival at your clinic evaluate the ABCs (airway, breathing, cardiac function) and perform a rapid but thorough physical examination (PE) and TPR.

Address and manage any non-neurologic life-threatening problems such as hypovolemic shock, excessive hemorrhage, or pneumothorax, etc.

Obtain a brief history as soon as possible. Items to focus on include:

1. Time since trauma occurred

2. Type/description of trauma

3. Status immediately after trauma (conscious? ambulatory?)

4. Method and manner of transport to clinic

5. Previous medical or surgical problems

6. Vaccination status (esp. Rabies vacc.)

Once life-threatening emergencies have been managed an initial neurologic evaluation can be done. Observations that can be made by the technician include:

1. Observation for hemorrhage in nasal cavity, ear canals, orbits, and nasopharyngeal regions

2. Palpation for presence of skull fxs

3. Specific neurologic observations include:

Level of Consciousness (best to worst)

- Normal – Bright, alert, responsive to environment

- Obtunded, depression – Lethargic, despondent but capable of responding to environment in a normal manner

- Delirium – Disoriented, irritable, fearful; capable of responding but usually response is inappropriate. Overreacts to minimal handling.

- Stupor (semi comatose) – Responsive only to noxious stimuli, otherwise animal is unaware of surroundings

- Coma – unconscious and unresponsive to even repeated noxious stimuli

*Note! Seizures which appear soon after trauma many times indicate intraparenchymal cerebral hemorrhage.

Pupillary size/response: Assess for symmetry, size, and response to light. This assessment should preferably be done every 30 minutes during the initial 3 hours of hospitalization and then every 1-2 hrs. for the remainder of the 1st 24 hours. Unilateral, slowly progressing pupillary abnormalities are characteristic of brain stem compression and/or herniation. Acute onsets of bilateral pupillary abnormalities are more suggestive of brain stem hemorrhage.

Oculocephalic/tonic eye/doll's head reflex: This test is performed by holding the animal's head in a normal position (with the nose pointed forward) and them moving the head to the right and left briskly and observing for an initial deviation of the globes in a direction opposite to the movement of the head. This initial slow deviation is the tonic eye reflex. This reflex tests the integrity of the vestibular input to cranial nerves 3, 4, and 6, and, if absent, points to brain stem (medulla) damage, which is a poor sign.

Motor responses: Animals that are not comatose, but have an altered state of consciousness usually maintain some voluntary motor activity. If there is brain stem damage, weakness on one side of the body (hemiparesis) or all 4 limbs (tetraparesis) may be seen. Voluntary motor activity is absent in the comatose patient. One form of motor activity called decerebrate rigidity is exemplified by the animal that is in lateral recumbency, has extensor rigidity in all 4 limbs, and many times has the head extended backwards over the neck (Opisthotonus). This motor activity is usually constant. It signifies severe midbrain damage and almost always points to a grave prognosis.

Patterns

If any of these respiratory patterns are documented the prognosis should be guarded to grave, but in the author's experience, if the patient has hyperventilation and pinpoint pupils the prognosis is better than for the other 3 respiratory patterns.

Summary of treatment for severe head trauma

1. No jugular catheters

2. Elevate head at a 30° angle

3. Lasix – 0.5-2.0 mg/kg, IV, q 6hr – do not give beyond first 24hrs

4. Methylprednisolone (Sol-U-Medrol, Upjohn)

- 30 mg/kg IV Bolus

- 12.5 mg/kg IV Bolus at 2 and 4 hours

- 2.5 mg/kg hr for next 18 hours

5. Hyperventilation- 10-20 breaths/min with 100% O2 for 1-2 hours. Most effective method is via endotracheal tube, therefore if animal is not comatose or stuporous, then heavy sedation or light anesthesia with propofol may be needed to facilitate intubation.

6. Mannitol – 0.25-2.0 gm/kg over 30minutes. Can be given q 3-8 hours for a maximum of 3 doses in 24 hours.

7. Oxyglobin: may have several beneficial properties in the head trauma patient. Dosages as low as 3-6 ml/kg may provide neuroprotective effects.

8. Seizures? Use diazepam (5-10 mg IV bolus) as needed followed by Phenobarbital (2 mg/kg IV, IM BID-TID). If szs are numerous, then pentobarbital may be required.

9. Surgery?? Craniotomy to decrease intracranial pressure

Patient monitoring/prognosis

The patient should ideally be evaluated every 15-60 minutes for the first 24 hours depending upon the initial patient status. All usual patient husbandry should be performed for a recumbent animal. In the author's experience, any patient remaining comatose for longer than 48 hours has a very grave prognosis for recovery. Included is a coma scale that Dr. Andy Shores has developed to aid in establishing a prognosis during the initial 24 hours.

Coma scale

Small Animal Coma Scale (SACS). Neurologic function is assessed for each of the three categories and a grade of 1 to 6 is assigned according to the descriptions for each grade. The total score is the sum of the three category scores. This scale is designed to assist the clinician in evaluating the neurologic status of the craniocerebral trauma patient. As a guideline and according to clinical impressions, a consistent total score of 3 to 8 represents a grave prognosis, 9 to 14 a poor to guarded prognosis, and 15 to 18 a good prognosis. (Modified from the Glasgow Coma Scale used in humans).