CNS

Question 1

When doing a lumbar puncture, what information do we gather?

Answer 1

1. CSF pressure (indicates pressure on brain)
2. Fluid colour (infection, haemolysis, bleeds)
3. Fluid contents (WCCs/proteins present)

Question 2

Where do we insert our needle during a lumbar puncture?

Answer 2

Equidistant between the iliac crests.

Between L3-4 or L4-5 (lumbar cistern: subarachnoid spaceL2-S2)

(Since spinal cord finishes at L2)

• we go through deep muscle > ligaments > dura (pop!)

Question 3

What is a normal intracranial pressure? (In mmhg)

Answer 3

<15 mmhg

It is normal for it to be low, this means the brain stem isn’t pushed down the foremen magnum.
It can even become negative when standing

Question 4

What is a raised intracranial pressure? (In mmhg)

Answer 4

> 20 mmhg

Question 5

What is the monroe-Kelly doctrine?

Think of raised intracranial pressure

Answer 5

The skull is a fixed volume, so it’s compliance decides the intracranial pressure

Compliance = Increase in one component of the skull contents displaces another component(brain, CSF, blood)

Three phases of increased intracranial volume exist:

1. High compliance = blood and CSF exit the skull so ICP doesn’t increase as intracranial volume increases
2. Compliance lowers = no more blood or CSF to remove, ICP starts to rise as intracranial volume increases
3. No compliance = as intracranial volume increases the ICP rises very rapidly

Question 6

Which infections occur with a clear CSF?

Answer 6

Fungal and viral

Question 7

Which infections cause the CSF to be turbid (cloudy)?

Answer 7

Bacterial and TB infections

Question 8

Which infections cause CSF to become viscous?

Answer 8

Fungal and TB

Question 9

In bacterial meningitis, which will be increased: polymorphs or lymphocytes?

Answer 9

Bacterial = increased polymorphs

Question 10

In viral meningitis, which will be increased: polymorphs or lymphocytes?

Answer 10

Viral = lymphocytes increased

Question 11

In fungal meningitis or TB, which will be increased: polymorphs or lymphocytes?

Answer 11

Fungal and TB = increased polymorphs AND increased lymphocytes

Question 12

In bacterial meningitis, how will the glucose and protein levels be in CSF?

Answer 12

Bacterial:

Very low glucose

High protein

Question 13

In viral meningitis, how will the glucose and protein levels be in CSF?

Answer 13

Viral:

Glucose is normal (no consumption)

Protein is raised

Question 14

In TB and fungal meningitis, how will the CSF protein and glucose be affected?

Answer 14

TB and fungal:

Glucose is low

Protein is very high

Question 15

A patient presents with a headache:

What extra finding or circumstance would indicate for neuroimaging?

Basically the associated red flags.

(Examination, natural history, high risk groups)

Answer 15

• Focal neurological signs (On examination e.g. visual change, muscle weakness)
• A change in headache semiology (A change in the pattern and severity of longstanding headaches)
• Nocturnal headaches (Worsening headaches which are waking the patient at night)
• New onset headache in the middle aged .

Question 16

A patient presents with unilateral headache and temporary loss of vision in the same sided eye:

What is your first test?

Answer 16

ESR and CRP

This is giant cell arteritis presentation, a medical emergency.

Question 17

How do you confirm your diagnosis of giant cell arteritis? (AKA temporal arteritis)

Answer 17

Temporal artery biopsy in multiple places

Question 18

What is the first line investigation for suspected subarachnoid haemorrhage?

Answer 18

CT head

Question 19

What does the glass test indicate for? And why is it relevant to meningitis investigations?

Answer 19

If a clear glass tumbler placed in a rash does not make the rash disappear under pressure, it indicates septicaemia

Sepsis is a contraindication for lumbar puncture

Question 20

Which signs are contraindications for lumbar punctures?

Answer 20

New onset rash (Sepsis)

Thrombocytopenia (can’t clot puncture site)

Signs of infection (fever, inflammation - sepsis risk)

Papilloedema (raised ICP means depressurisation can pull brain stem downwards - resp depression)

Focal neurological signs (indicate SOL and raised ICP)

Overall:

1. Signs of raised ICP
2. Coagulation defects
3. Signs of infection near puncture site

Question 21

What are the signs of a brain tumour on MRI?

Answer 21

The tumour itself may be visible.

Local swelling around the tumour.

Guru and sulci are lost: outer border of affected hemisphere is smooth (roughenings are gyru and sulci)

Question 22

What are the signs specific to a space occupying lesion in the occipital lobe?

Answer 22

Visual field loss: hemianopia, loss of vision to one/both eyes

Question 23

What are the signs specific to a space occupying lesion in the parietal lobe?

Answer 23

Sensory symptoms: anosmia, touch, recognition.

Aphasia and coordination difficulties.

Visual field defects.

Question 24

What are the signs specific to a space occupying lesion in the temporal lobe?

Answer 24

Dysphasia

Visual field defects (adjacent to optic nerve route)

Question 25

What are the signs specific to a space occupying lesion in the cerebellum?

Answer 25

Cranial nerve palsies Tremors Nystagmus Dysmetria (lack of coordination of movement, causes overshooting and undershooting) Ataxic gait

Question 26

What are the signs specific to a space occupying lesion in the frontal lobe?

Answer 26

Personality change Dementia Dysphasia Muscle weakness

Question 27

How many 30+ minute headaches do you need per month to be diagnosed with chronic tension headache?

Answer 27

>15 headaches per month for more than three months

Question 28

How do we diagnose cause of transient loss of consciousness?

Answer 28

Most of the diagnosis is down to the history; it can present significant opportunity to be incorrectly diagnosed. ``` In short: Diagnosis of exclusion Uncomplicated vasovagal syncope Situational syncope Orthostatic hypotension Epilepsy Cardiogenic ``` ``` 1. History from the patient Presyncopal symptoms (light headedness, dizziness, visual blurring, ringing in ears, auditory distortion, sweating, feeling cold) ``` ``` Seizure symptoms (Pre-seizure: epigastric rising sensation, abnormal taste/smells, dejavu.) (Post-seizure: where were they after, confusion, recognise people around them) ``` ``` 2. History from witnesses: What they were doing Posture before event Any warning symptoms Colour change Pale/red in the face Movement in the limbs; stiffness, jerking or twitching How long did movements continue for Tongue biting (which side) Injury during the event Duration of event How long after movement stops did patient come around Weakness down one side during recovery Confusion present/absent ``` ``` 3. Past history: Previous episodes, number and frequency Medical history Family history of cardiac disease Current medications ``` 4. Vital signs, neurological and cardiovascular examinations 5. 12 lead ECG, look for red flags: - heart blocks - evidence of long or short QT intervals - ST segment abnormalities - T wave abnormalities - Persistent Bradycardia - L/RVH - Atrial arrhythmias - Heart murmur - New/unexplained dyspnoea - Family history of sudden cardiac death under 40 6. If red flags found: urgent referral to cardiology - If NO red flags found: 7. Diagnose uncomplicated vasovagal syncope (AKA faint) if: No features of alternative diagnosis Features are PPP ; -posture is prolonged standing/prevented by lying -provoked by pain or medical procedure -prodromal symptoms (sweating, feeling warm before) 7. Diagnose situational syncope if: No features of alternative diagnosis Syncope is consistency provoked by straining during micturition, coughing or swallowing = micturition syncope, cough syncope or swallow syncope 8. Diagnose Orthostatic hypotension if: No features of situational/uncomplicated syncope Provocation is caused by changing from lying/sitting to standing Measure sitting and standing BP to confirm. 8. Suspect epilepsy when they have 1 or more feature: Bitten tongue Head turning to one side during TLOC No abnormal behaviour beforehand Unusual posturing Prolonged limb jerking (short jerking can occur in faints) Confusion after the event Prodromal deja vu -Refer for specialist assessment within 2 weeks- ``` Features making it less likely: Prodromal symptoms abolished by sitting/lying Sweating before episode Prolonged standing precipitating TLOC Pallor during the episode ``` 8. Investigate for cardiogenic syncope, Epilepsy and orthostatic hypotension not suspected: Refer for specialist cardiovascular assessment Repeat ECG and investigate for arrythmias, structural heart disease, neurogenic (vasovagal and carotid sinus) syncope

Question 29

How do we diagnose epilepsy?

Answer 29

1. Screen in A+E based on history: Abnormal movements predominates Disturbed awareness, thoughts and sensations predominate -These two categories have subcategories that narrow the list of possible differentials- 2. Refer to specialist for epilepsy 3. Diagnosis is not made based on the presence/absence of single features If any uncertainty exists, referral to a cardiogist is to be considered 4. EEG performed to support diagnosis of epilepsy Helps determine seizure type and epilepsy syndrome (based on age of onset, seizure type, EEG characteristics and other features) 5. Neuropsychological assessment: in cases of learning disabilities or cognitive dysfunction 6. Neuroimaging by MRI: Identify any abnormalities that may be causing epilepsy, potentially supported with blood tests - Final product is 1) seizure type 2) epilepsy syndrome, and 3) aetiology

Question 30

What are the recommendations for a patient attending a first seizure clinic?

Answer 30

1. Don’t drive 2. Bring someone who witnessed the seizure They are not normally given anti epileptic medication unless condition causing epilepsy makes another seizure very likely - e.g. brain tumours

Question 31

In a patient with reduced GCS after a seizure, what should be the first investigation?

Answer 31

Blood glucose Anyone with altered conscious level must be suspected of hypoglycaemia. Hypoglycaemia could also be the cause of the seizure.

Question 32

In the case of a post-operative surgical patient who has a seizure (and no history of seizures) what should be the first investigation?

Answer 32

Serum electrolytes - hyponatremia and hypernatremia can both cause seizures In the post-operative stage, patients receive IV fluids, these can contain insufficient or excess sodium, thereby inducing seizure.

Question 33

How is a seizure defined as general or focal?

Answer 33

If it starts on one side it is focal, regardless of any ensuing progression to bilateral.

Question 34

What features should we expect from a non-epileptic attack disorder?

Answer 34

Gradual onset Prolonged duration Abrupt termination Accompanied by: closed eyes, rapid breathing, fluctuating motor activity, and episodes of motionless unresponsiveness. CNS exam, CT, MRI, and EEG are normal. It may coexist with true epilepsy

Question 35

How do you diagnose encephalitis?

Answer 35

FBC Cultures and CSF sampling CT