Neurological emergency book

What is the relationship between size of endotracheal tube and breathing resistance ?

Resistance of breathing increases as endotracheal tube decreased.

If diameter of the tube is halved, resistance increased to 16 fold

Link between ETT lenght and expiratory resistance

Doubling length of the tube will double the expiratory resistance flow.

What cause a long ETT on expired CO2

It increased the dead space and lead to re breathing of expired CO2

What happen when there's an increase pressure on trachea due to ETT

Risk of pressure necrosis on tracheal mucosa,so pressure within the cuff should not exceed 25 mmHg

Indication of tracheostomy

Chronic management of airway dysfunction in conscious patient ( tetanus, laryngeal paresis)

To reduce the amount of sedation or anesthesia

Several laryngeal trauma, obstruction of the airway

How to choose the size of the tracheostomy tube ?

Diameter of the tube is one half the diameter of trachea to allow breathing of the tube occlude

what can be the cause of tachy arrhythmia in neuro patient ?

Brainstem compression/ischaemia, trauma-related myocardial injury, hypovolaemia/ischaemia, electrolyte/acid–base disturbances, pain.

what can be the cause of Bradyarrhythmias in neuro patient ?

• Brainstem compression → Cushing reflex: hypertension → reflex bradycardia.

• Drugs: opioid overdose especially in daschund, alpha 2 agonist, miochiline betanechol,

• Systemic issues: severe hypothermia, K⁺ abnormalities (hyper/hypokalaemia).

what can be the cause of Poor Myocardial Contractility in neuro patient ?

• Anaesthetic/sedative drug effects.

• SIRS from hypotension, hypoxaemia, ventilator injury, multi-trauma.

how do you managed poor myocardial contractility in neuro patient ?

Management:

• Reduce/stop causative drugs; use opioid-based multimodal anaesthesia; use short-acting, titratable agents.

• If inadequate response or urgent need: Inotropes

  • Dopamine 2–5 µg/kg/min

  • Dobutamine 2–5 µg/kg/min

Why do you check the cutaneous trunci reflex from lumbar to thoracic region ?

because It can be decreased at the certain point and normal cranial and caudal to it

hemi-­ inattention is the correct wording

hemi-­ inattention is the correct wording

what is pseudohyperreflexia

what are the muscles of mastication

rostral digastricus, middle and lateral pterygoideus, temporalis, masseter, mylohyoideus

what are the sensory and the motor nucleus of the IX, X nerves

 the glossopharyngeal (CN IX) and vagus (CN X) nerves share sensory (nucleus solitarius) and motor (nucleus ambiguus) nuclei.

what is the minimal intracranial blood pressure

needs to be over 70 mmHgw

what is the reason and the clinical signs of hypovolemic shock ? 

which anesthetic drugs can cause vasodilation

isofluran, servofluran, propofol but less pronounced

How do you approach a spinal radiographs ?

• vertebral canal as a whole (alignment, steps, luxation)

• width of vertebral canal

• alteration in opacity

• disc space narrowing

• intervertebral foramina

• endplate changes

• incidental findings

How much percentage of bone needs to be lost during lysis to be seen on Rx?

50% of mineral must be lost to be seen on Rx

What is the approximate accuracy of disc space narrowing as a sign of disc herniation in Rx?

About 70%; false positives are common

In chondrodystrophic dogs, what does disc mineralization usually represent in Rx?

Chondroid degeneration—often a normal age-related finding, not necessarily clinically significant.

In non-chondrodystrophic dogs, what does disc mineralization indicate in Rx?

Pathological disc degeneration, though not always clinically relevant.

What does dorsal displacement of mineralized disc material indicate?

Disc herniation; significance must be assessed with myelography or advanced imaging (MRI/CT).

What is the “vacuum phenomenon” in spinal radiography?

Presence of gas in the disc space; a specific but insensitive indicator of acute disc herniation.

Which disc space is normally narrowed in dogs and should not be overinterpreted?

C2–C3

Which thoracic disc space is naturally narrowest?

T10–T11, with progressive widening caudal to T11–T12.

What is a normal anatomical variation in cats that may mimic disc collapse?

Wedge-shaped disc spaces.

Which disc space is normally wider than other lumbar discs?

L7-S1

What radiographic feature helps differentiate pressure atrophy from lytic vertebral tumors?

Pressure atrophy → smooth margins;
Tumors → irregular margins.

What radiographic finding is typical of discospondylitis?

Irregular, ragged endplate lysis involving adjacent endplates.

When is spondylosis deformans clinically significant?

When the proliferative bone extends dorsolaterally and impinges on the intervertebral foramen.

In which neurolocalization regions is myelography not recommended?

• Brachial plexus (C6–T2 focal peripheral)

• Cauda equina

• Mononeuropathies

What is the most common complication of myelography and what increases the risk?

Seizures (up to 21%). Increased risk with:

• Dogs >20 kg

• Cerebellomedullary injections

• Higher contrast medium concentration

Name additional risks associated with myelography.

• Temporary worsening of neurologic status

• Iatrogenic CNS injury

• Cardiac arrhythmias

• Respiratory arrest

• Death

What are the contraindications for myelography?

• Coagulopathy (including thrombocytopenia, thrombocytopathia)

• Spinal instability (relative; depends on fracture site and safety of positioning)

• Cloudy/turbid CSF (suggests infectious/inflammatory process)

What are the components of the dorsal compartment in the 3-compartment spinal trauma model?

Articular processes, laminae, pedicles, spinous processes, supporting soft tissues

What structures form the middle compartment? for the 3 compartment model

Dorsal longitudinal ligament, dorsal annulus fibrosus, dorsal aspects of vertebral bodies

What structures form the ventral compartment? for the 3 compartment model

Ventral vertebral body, lateral & ventral annulus fibrosus, disc nucleus, ventral longitudinal ligament.

According to the three-compartment model, when is a spinal injury considered unstable?

When ≥2 of the 3 compartments are disrupted/damaged.

When does a stable fracture still require surgery?

If spinal cord compression is present due to a bone fragment.

What is the sensitivity of survey radiographs for detecting vertebral fractures?

~72%.

What is the sensitivity of radiographs for detecting bone fragments in the vertebral canal?

~57%.same as vertebral canal narrowing

Where do spinal fractures most commonly occur in small animals?

At junctions of mobile and less-mobile regions: cervicothoracic, thoracolumbar, lumbosacral.

What soft-tissue complication of cervical spinal trauma may cause respiratory distress?

Severe soft-tissue swelling → upper airway obstruction.

is iatrogenic blood contamination a contraindication to myelography?

No, if contamination is obvious (initially clear CSF then blood swirl).

Why should contrast medium be warmed before use?

To reduce viscosity and minimize adverse effects

What needle types are used for myelography in small animals?

pinal needles, typically 22–20 gauge.

What type of contrast medium must be used for myelography?

Non-ionic, low-osmolar, iodinated, water-soluble (e.g. iohexol).

Why are ionic contrast media contraindicated?

Injection into subarachnoid space may be fatal.

What contrast concentration is recommended?

240–300 mg iodine/ml.

What are the usual contrast volume guidelines?

• Minimum: 2 ml

• Regional exam: 0.3 ml/kg

• Whole spine: 0.45 ml/kg (maximum)

Do larger animals require relatively more or less contrast per kg?

less per kg

What is the most common artefact with lumbar myelography?

epidural leakage

What should be done if all contrast is accidentally injected epidurally?

Wait ~15 minutes → resorption allows repeat injection.

Name causes of intramedullary swelling.

Intramedullary masses, ischemic myelopathy, contusion/hemorrhage, syrinx, myelitis.

What is the characteristic myelographic sign of intradural/extramedullary masses?

golf tee sign

What does contrast extension into the spinal cord indicate prognostically?

Poor prognosis → myelomalacia.

Best use for T2* GRE?

Detecting hemorrhage + bone changes.

What pathology is best seen on DWI?

Hyperacute infarcts.

What is the utility of STIR or fat-sat T1 post-contrast?

Detect soft tissue/bony marrow disease → especially for back pain localization.

What artefact may mimic skull bone loss on MRI?

Partial volume averaging.

How does brain ageing appear on MRI?

Sulcal widening + ventricular dilation.

Which breeds commonly have ventricular asymmetry and incomplete septum pellucidum?

brachycephalic

What MRI findings suggest pathological hydrocephalus rather than normal ventriculomegaly?

Rounded ventricles + periventricular FLAIR hyperintensity (halo).

What is a common incidental finding in CKCS on MRI?

Fluid or tissue in tympanic bullae (primary secretory otitis).

How do metastatic brain lesions typically appear?

Multiple, small, located at grey–white junction with marked edema.

Why is acute hemorrhage hyperattenuating on CT?

Due to X-ray attenuation by the globin portion of blood.

When does a hematoma become isodense on CT?

1 month

When does peripheral enhancement of a hematoma appear on contrast CT?

6 days to 6 weeks, due to revascularization.

Which MRI sequence is most sensitive for detecting hemorrhage?

T2* GRE — hemorrhage appears hypointense (signal void).

How does DWI help in dating infarcts?

• <9 days: hyperintense on DWI, hypointense on ADC

• 7–9 days: DWI pseudonormalizes

Typical MRI features of metabolic disease?

Bilaterally symmetrical hyperintensity on T2, minimal/no mass effect, no abnormal contrast enhancement.

MRI changes post-seizure in dogs?

Increased T2/FLAIR signal in piriform lobes, may extend to hippocampal gyrus, sometimes cingulate gyrus.

How to differentiate post-seizure changes from tumor?

Presence of mass effect or swelling favors tumor.

Compensatory hydrocephalus (ex vacuo) MRI features?

Ventriculomegaly + widened sulci, no calvarial thinning, often due to chronic brain parenchymal loss

Meningeal enhancement patterns on MRI?

• Dural: no extension into sulci

• Pial: extends into sulci (abnormal)

MRI signs of chronic disc protrusion?

Low-signal disc material protruding into vertebral canal, spinal cord atrophy, preservation of dorsal subarachnoid space/epidural fat.

Typical MRI findings?

Focal, asymmetrical T2 hyperintensity, primarily central grey matter, sometimes extending into white matter, irregular shape, variable cord swelling.

hydrocephalus congenital type MRI

Lateral ventricle dilation, cortical thinning, open fontanelle in toy breeds

Secondary/obstructive hydrocephalus, MRI?

3rd/4th ventricle dilation, periventricular FLAIR signal, contrast-enhancing masses possible (FIP, choroid plexus tumor)

Compensatory (ex vacuo) hydrocephalus MRI ?

entriculomegaly + widened sulci, no calvarial thinning

which view

Lateral oblique cervical spine view (20-30°)

other name of T2 shine-through

facilitated

otherwise version to describe B01/ B600 , ADC map

BO1: same as T2 , B600 highlight the area of restrictive diffusion so like DWI . ADC map : color ADC

hematolma on T1 on MRI

T1: hyperintense, rim is hypointense in T2 , big hemorrhages : fluid interphase, homogeneous , if heterogenous speaks for tumor

subarachnoid diverticulum —> tear drop on RX and MRI

CSF artefact

T2*

artefarctual nerve root masses

STIR

what are the abbreviation for STIR

which structures should show contrast enhancing in a normal animal

vessel, hypophysis, trigeminal nerve,

structure that are outside the BBB

area ostrema, and ???

which are the site of production of CSF

choroid plexuses of the lateral, third and

fourth ventricles

the brain by way of the ependymal lining of the ventricular system and the pial–glial membrane covering its external surface

the blood vessels in the pia-arachnoid

question 15 Nicolas

Cushing, CKD, PLN,

cingulate gyrus can be mildly asymmetric

what is the CSF

an ultra filtrate of the blood plasma

what are the contra indication for CSF collection ?

• Patient unstable for general anaesthesia

• Evidence of coagulopathy

• Instability or pathology suspected at the site of collection (e.g. atlanto-axial instability)

• Severe hydrocephalus

• Recent head trauma

• Imaging evidence of intracranial mass lesion oedema/haemorrhage causing mass effect

• Clinical indication of increased intracranial of collection or pressure

huge dermatological lesion at the region of puncture

why there is not a decreased risk for a lumbar tap when the cisternal tap is contraindicated

because the subarachnoid space becomes continuous between the 2 sites