Encephalitis

Question 1

What is the most common cause of encephalitis?

Answer 1

Viral, especially HSV-1

Question 1

What is encephalitis?

Answer 1

Acute inflammation of the brain parenchyma

Question 2

Name three viruses (other than HSV-1) that can cause encephalitis

Answer 2

1. VZV
2. Enteroviruses
3. Adenovirus (also HHV-6/7)

Question 3

What is limbic encephalitis, and what is it associated with?

Answer 3

Antibody-mediated encephalitis affecting the limbic system; may be paraneoplastic (associated with malignancy) or autoimmune

Question 4

What are the typical symptoms of encephalitis?

Answer 4

1. Fever
2. Meningism
3. Personality/behavioural change
4. Seizures
5. Focal neurological deficits
6. Reduced consciousness

Question 5

What feature helps distinguish encephalitis from meningitis?

Answer 5

1. Prominent behavioural and personality changes
2. Seizures
3. Focal deficits due to brain parenchyma involvement

Question 6

What is the most sensitive imaging for encephalitis?

Answer 6

MRI
(shows focal temporal lobe involvement in HSV)

Question 7

What would you expect on a lumbar puncture in viral encephalitis?

Answer 7

1. Elevated lymphocytes
2. viral DNA detected by CSF PCR

Question 8

What investigation helps confirm limbic encephalitis?

Answer 8

Detection of specific antibodies in serum or CSF

Question 9

What is the first-line treatment for suspected viral encephalitis?

Answer 9

IV acyclovir — start immediately, before results return

Question 10

Why is IV ceftriaxone (or cefotaxime) often given alongside acyclovir?

Answer 10

To cover possible bacterial meningitis until it is excluded

Question 11

How is autoimmune/paraneoplastic limbic encephalitis managed?

Answer 11

1. Immunosuppression (steroids)
2. Tumour treatment
3. IV immunoglobulin, or plasmapheresis

Question 12

How can you distinguish meningitis from encephalitis based on symptoms?

Answer 12

Meningitis mainly causes
(1) fever
(2) headache
(3) neck stiffness
(4) photophobia with usually preserved consciousness

whereas encephalitis causes
(1) behavioural/personality changes
(2) seizures
(3) focal neurological deficits
(4) reduced consciousness due to brain parenchyma involvement

Question 13

How does consciousness differ in meningitis vs encephalitis?

Answer 13

Meningitis → usually preserved early

Encephalitis → often reduced, may progress to coma

Question 14

Which symptom helps distinguish encephalitis from meningitis in an exam scenario?

Answer 14

Prominent confusion, behavioural change, or seizures → indicates parenchymal involvement

Question 15

What are the key investigations in suspected acute encephalitis?

Answer 15

CNS imaging
(CT at first, MRI subsequently)

Lumbar puncture
(including CSF viral PCR)

Question 16

What is the most appropriate site for lumbar puncture?

Answer 16

1. L4-5 intervertebral space
2. At the level of the iliac crests posteriorly

Question 17

What area of the brain is typically affected by Herpes Simplex Virus encephalitis?

Answer 17

Temporal lobe

Question 17

What is the most common infectious cause of encephalitis?

Answer 17

Herpes simplex virus

Question 18

What is the treatment for HSV encephalitis?

Answer 18

IV Aciclovir

Question 19

What are the features of encephalitis?

Answer 19

1. Headache and meningism
2. Fever and systemic upset
3. New-onset altered mental status
4. New-onset seizures
5. Flu-like prodromal illness

Question 20

A 60-year-old man is brought to the emergency department with confusion. He complains of a headache and appears photophobic. He is unable to give a coherent history and is behaving oddly during the assessment. His temperature is 39 °C. His neck is stiff on passive movement. He is poorly compliant with the neurological assessment, but appears to have full power in his limbs, and there is no facial asymmetry.

Routine blood tests show a normal FBC. Serum sodium is 130 mmol/L (normal range 135-145 mmol/L). CT head is performed and shows hypodensity in the temporal lobes bilaterally.

What is the next best step in the management of this patient?

Answer 20

Start IV acyclovir

Question 21

A 19-year-old university student is brought to A&E by ambulance after her flatmates noticed she was becoming very aggressive and confused.

On assessment she was pyrexial and complained of a headache. She denied any foreign travel, alcohol or recreational drug use. There were no localising signs on examination, and no photophobia. Her neck is soft and supple. Blood tests are unremarkable.

What treatment is the most important to initiate?

Answer 21

IV Aciclovir

Question 22

A 52-year-old man presents to the emergency department with a new onset of confusion and odd behaviour, associated with a fever of 39. Clinical examination is unremarkable, and chest x-ray and urine dip confirm that his chest and urine are clear.

A clinical diagnosis of encephalitis is suspected, and first-line investigations are sent. A CT scan shows bilateral involvement of the temporal lobes.

What is the single most useful diagnostic investigation?

Answer 22

CSF viral PCR

Question 23

A 56-year-old man presents to A&E with a severe headache which worsens when looking at light. He is noted to have a stiff neck and fever. Neurological examination is unremarkable, and he is not found to have a rash. However, he behaves strangely during the consultation, crawling on the floor and often needing several prompts to answer his doctor's questions. What is the most likely diagnosis?

Answer 23

Viral Encephalitis

Question 24

A 45-year-old woman with HIV presents to the Emergency Department with confusion, a change in behaviour and a GCS of 14. She is also complaining of a headache. She has witnessed a seizure in the department. She has recently not been taking her antiretrovirals, and in clinic last week had a high viral load with a CD4 count of 50. On examination, she has a temperature and is notably postictal. She has a vesicular rash on her body that started around her mouth. Other than that, she examines well, but her upper limb power is 4/5 on the MRC scale. She has a CT head before an LP to confirm the diagnosis. What describes the most likely CT head findings?

Answer 24

Focal bilateral temporal lobe involvement

Question 25

A 41-year-old woman presents to the Emergency Department with a generalised, photophobic headache. Whilst being seen by a doctor, she vomits. Throughout history, her doctor notes that she is behaving bizarrely and appears confused. On examination, she is febrile and is unable to flex her neck. Neurological examination otherwise shows no physical abnormalities. Her doctors suspect encephalitis and order an MRI scan Which sign on MRI would support the diagnosis of encephalitis?

Answer 25

Bilateral medial temporal lobe involvement

Question 26

A 31-year-old man prisoner presents to A&E with a new onset of confusion. During the consultation, he says very little, although the prison officers say that he has been behaving oddly over the last 5 days. During assessment, he suffers a convulsive seizure, which is terminated with IV lorazepam. On examination, he is alert, but confused (GCS 14), with a fever of 39, tachycardia of 122 and tachypnoea of 26. Blood pressure and saturations are normal. Initial blood tests reveal a neutrophilic leukocytosis and raised CRP. A CT head is unremarkable, and a lumbar puncture reveals lymphocytes and raised CSF protein. What is the most likely underlying diagnosis?

Answer 26

Acute encephalitis

Question 27

A 35-year-old male presents with 2 weeks of cognitive dysfunction, including memory loss, difficulty concentrating, and confusion. He has also had behavioural changes such as agitation, aggression, and emotional lability. His symptoms have been progressively worsening, and his family reports that he has had some seizures in the past week. His neurological exam is significant for confusion and agitation. Imaging shows no evidence of acute lesions, and his CSF is positive for antibodies against the N-methyl-D-aspartate (NMDA) receptor. What is the best initial treatment for this patient?

Answer 27

Intravenous (IV) methylprednisolone and IV immunoglobulin

Question 28

On examination, he has a fever of 38.5 °C with otherwise normal observations. His blood glucose level is 5.6 mmol/L. Cranial nerve examination is normal, but his peripheral nerve examination shows reduced power on his left side. He has negative Kernig and Brudzinski signs. Blood tests show raised inflammatory markers, and a lumbar puncture shows lymphocytosis with normal protein and glucose in the cerebrospinal fluid (CSF). A CT head is normal. Given the likely diagnosis, what is the next best step in management?

Answer 28

Start intravenous acyclovir and ceftriaxone

Question 29

A 23-year-old man is brought into the emergency department after a generalised tonic-clonic seizure. Over the past 4 days, he has had a fever, headaches, drowsiness and experienced irritability. He is known to have HIV, but his viral load and adherence to antiretroviral therapy are not known. (1) Pulse = 85 beats per minute (2) Blood pressure = 134/74 mmHg (3) Oxygen Sats = 97% He has nuchal rigidity but no rashes are noted. A CT scan of the head shows ill-defined hypodense areas in the bilateral temporal lobes and inferior frontal lobes. What does he have?

Answer 29

Encephalitis

Question 30

When a patient has features of both meningitis and encephalitis what is this called?

Answer 30

meningoencephalitis

Question 31

A 70-year-old man presents to the emergency department after a witnessed generalised tonic-clonic seizure. His wife tells you that he is not known to have seizures and that over the past 3 days, he has become quiet and withdrawn. He had a viral upper respiratory tract infection 3 weeks ago. On examination, the patient is withdrawn but alert. Tendon reflexes are brisk, but there are no other neurological findings. There is no visible rash or neck stiffness. CT head reveals no obvious intracranial masses and no signs of herniation. Given the likely diagnosis, what is the next most appropriate investigation?

Answer 31

Cerebrospinal fluid PCR