QuestionSBA
QuestionChoice
Migraine typically presents with unilateral throbbing pain, worsened by light and noise. Although this patient has photophobia, the presence of neck stiffness and fever is more suggestive of a diagnosis of meningitis
33736
d
Migraine
QuestionChoice
Meningococcal septicaemia is caused by Neisseria meningitidis infecting the blood. This can present as a petechial rash (usually non-blanching) with or without haemodynamic compromise. This patient does not present with these features; therefore, this is less likely than meningitis
33735
c
Meningococcal septicaemia
QuestionChoice
Subarachnoid haemorrhage presents as a "thunderclap headache" to the back of the head, which is very painful and may feel as though they have been hit in the back of the head. They may also have features of meningism (neck stiffness, photophobia) as blood irritates the meninges. The longer history and presence of fever, in this case, make meningitis more likely
33734
b
Subarachnoid haemorrhage
QuestionChoice
Meningitis is caused by inflammation of the meninges lining the brain. Clinical presentation includes: a triad of headache, neck stiffness and photophobia; fever; focal neurology; seizure or features of meningococcal septicaemia. As this patient is presenting with features of meningism and fever, meningitis is the most likely diagnosis
33733
a
Meningitis
QuestionChoice
Space occupying lesions typically present with red flag symptoms including: morning headache; headache on coughing, straining or lying down; vomiting; focal neurological signs; personal history of cancer. This patient is not presenting with any of these symptoms, and the history of meningism and fever make a diagnosis of meningitis more likely
33737
e
Space occupying neoplasm
Concept
Chapter
# Summary
 
Meningitis is a potentially life-threatening condition characterised by the inflammation of the meninges, the membranes enveloping the brain and spinal cord. Its causes span from infectious agents, such as bacteria, viruses, fungi, and parasites, to non-infective causes like malignancy and certain medications. Symptoms are often non-specific, necessitating accurate differential diagnoses and prompt investigations. Timely management, including empirical antibiotics and targeted therapy post-identification of causative agent, is crucial to mitigate complications and improve patient outcomes. 
 
 
# Definition
 
 
Meningitis is an inflammation of the meninges, which are composed of three layers: the dura mater, arachnoid mater, and pia mater. This inflammation may arise from both infective and non-infective aetiologies. 
 
 
# Epidemiology
 
 
Bacterial meningitis, while not the most common form of meningitis, is particularly significant due to its high morbidity and mortality rates. 
 
Viral meningitis, predominantly caused by enteroviruses, is more common but typically less severe. Fungal and parasitic causes are relatively rare, except in immunosuppressed individuals. 
 
In the United States, the annual incidence of bacterial meningitis is approximately 1.38 cases/100,000 population with a case fatality rate of 14.3%.

# Aetiology
 
 
Infective causes of meningitis include:
 
 
 - Bacterial: **Streptococcus pneumoniae (most common bacterial cause),** Neisseria meningitidis, Haemophilus influenzae, Listeria monocytogenes, among others.
 - Viral: **Enteroviruses are overall most common** (Echoviruses, Coxsackie viruses A and B, poliovirus), herpes viruses (HSV2, HSV1), Paramyxovirus, measles and rubella viruses, Varicella Zoster Virus, Arboviruses, Rabies virus.
 - Fungal: Particularly Cryptococcus neoformans, mainly affecting the immunosuppressed population.
 - Parasitic: Amoeba (Acanthamoeba), Toxoplasma gondii.
 
 
Non-infective causes of meningitis encompass:
 
 
 - Malignancies such as leukaemia, lymphoma, and other tumours
 - Chemical meningitis
 - Certain drugs, including NSAIDs and trimethoprim
 - Systemic inflammatory diseases such as sarcoidosis, systemic lupus erythematosus, Behcet's disease.
 
 
# Signs and Symptoms
 
 
The cardinal features of meningitis include:
 
 
- Headache
- Fever
- Neck stiffness
- Photophobia
- Nausea and vomiting
- Focal neurology
- Seizures
- Reduced conscious level
- Features of overwhelming sepsis, such as non-blanching petechial rash indicative of impending Disseminated Intravascular Coagulation (DIC). 
 
Specific signs suggestive of meningeal irritation (and therefore not specific to meningitis) include:
 
 
1. **Kernig's sign:** Kernig's sign is a test performed to evaluate the presence of meningeal irritation and stiffness in the hamstrings and lower back. To perform this test, the patient is positioned lying on their back with the hip and knee flexed at 90 degrees. The examiner then attempts to extend the patient's knee. If the patient experiences pain and resistance to knee extension, especially when attempting to straighten the leg, it is considered a positive Kernig's sign. This sign suggests meningeal irritation or inflammation.
 
 
2. **Brudzinski's sign:** Brudzinski's sign is another manoeuvre used to assess for meningeal irritation. This test involves passive neck flexion, where the examiner gently flexes the patient's neck forward toward the chest while the patient is lying on their back. If the patient involuntarily flexes their hips and knees in response to neck flexion, it is considered a positive Brudzinski's sign. This involuntary movement indicates irritation of the meninges.
 
 
 
 
# Differential Diagnosis
 
The key differentials for meningitis often present with overlapping symptoms. These include:
 
 
- **Encephalitis**: Headache, fever, altered consciousness, seizures, focal neurological signs, behaviour changes.
- **Subarachnoid hemorrhage**: Sudden severe headache, nausea and vomiting, neck stiffness, altered consciousness, seizures.
- **Brain abscess**: Headache, fever, nausea and vomiting, focal neurological deficits, seizures, altered mental status.
- **Sinusitis**: Headache, fever, facial pain, nasal congestion.
- **Migraine**: Recurrent headaches, often unilateral and throbbing, accompanied by nausea/vomiting, photophobia, phonophobia.
 
 
# Investigations
 
 
Diagnostic investigations for suspected meningitis include:
 
 
 - Blood tests: Full Blood Count, Urea and Electrolytes, Clotting, Glucose, PCT
 - Arterial Blood Gas
 - Blood cultures
 - Bacterial throat swab for meningococcus
 - PCR for meningococcus & pneumococcus
 - HIV test
 - Imaging: CT Head if there are signs of raised intracranial pressure (ICP)
 - Lumbar puncture for Cerebrospinal Fluid (CSF) analysis, once confirmed there are no signs of raised ICP.
 
 
## CSF Findings 
 
 
Analysis of the cerebrospinal fluid in acute meningitis can provide important clues as to the underlying aetiology. Once establishing that it is safe to do so, a CSF sample should be taken via lumbar puncture and the opening pressure should be measured.
 
 
This can be examined macroscopically, and then sent for haematology, biochemistry, and microbiological microscopy, culture and sensitivities, as well as PCR.
 
|                           | **Appearance**                      | **Predominant cell type**                          | **Culture**                                             | **Protein** | **Glucose** |
|---------------------------|-------------------------------------|---------------------------------------------------|--------------------------------------------------------|-------------|-------------|
| **Bacterial meningitis**   | Clear or turbid                    | **Polymorphonuclear** cells (i.e. neutrophils)     | Positive                                                | Raised      | **Reduced** |
| **Aseptic (viral) meningitis** | Clear or slightly turbid            | **Lymphocytes**                                    | Negative                                                | Raised      | **Normal**  |
| **Tuberculous meningitis** | Clear or slightly turbid ± fibrin web | **Lymphocytes** + polymorphonuclear cells         | Negative gram stain; acid-fast bacilli positive (auramine staining) | Raised      | **Reduced** |

 
N.b. Cryptococcal meningitis may give any of the above results, so should be considered as a differential in any HIV or immunocompromised patient. Classically the opening pressure is very high, and this is a poor prognostic sign. If suspected, request cryptococcal antigen or India Ink staining.
 
 
# Management
 
 
- Empirical antibiotic therapy for suspected bacterial meningitis typically includes 2g of IV ceftriaxone twice daily to ensure CNS penetration, with IV amoxicillin added in patients at age extremes for listeria coverage.
- In primary care, IM benzylpenicillin or ceftriaxone should be given while awaiting urgent transfer to hospital, especially if meningococcal disease is suspected.
- Dexamethasone should be given if bacterial meningitis is strongly suspected in the absence of a rash
	- This has been shown to reduce neurological sequelae in bacterial meningitis but not meningococcal meningitis
- In cases of suspected viral encephalitis, IV aciclovir should also be administered. For patients allergic to penicillin, alternatives such as chloramphenicol may be used. 
- It's important to note that any empirical antibiotic regimen should be adjusted based on culture results when available.
 
 **Additional notes**
 
Close contacts of the patient should receive prophylactic antibiotics. This will be guided by specialists but may be a single dose of oral ciprofloxacin, or rifampicin.
 
Bacterial meningitis is a notifiable disease and any suspected cases should be reported to the local health protection team.
 
 
# Complications
 
 
Meningitis may lead to severe complications if not promptly treated, such as:
 
 - Septic shock
 - Disseminated Intravascular Coagulation
 - Coma
 - Subdural effusions
 - Syndrome of inappropriate antidiuretic hormone secretion
 - Seizures
 - Delayed complications: Hearing loss, cranial nerve dysfunction, hydrocephalus, intellectual deficits, ataxia, blindness
 - Death
 
 
# NICE guidelines
 
 [NICE CKS: Meningitis - bacterial meningitis and meningococcal disease](https://cks.nice.org.uk/topics/meningitis-bacterial-meningitis-meningococcal-disease/)
 
 [NICE: meningitis (bacterial) and meningococcal disease: recognition, diagnosis and management](https://www.nice.org.uk/guidance/ng240/resources/meningitis-bacterial-and-meningococcal-disease-recognition-diagnosis-and-management-pdf-66143949881029)
 
# References
 
 [BNF: Ciprofloxacin](https://bnf.nice.org.uk/drugs/ciprofloxacin/)
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Picture
The typical appearance of a petechial rash.
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Petechiae - free.jpeg
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2683
Meningitis
Topic
34
Neurology
6747
A 20-year-old university student presents to the emergency department with a one-day history of headache. On examination, you notice he is wearing sunglasses. He is unable to touch his chin to his chest, but tone, power, and reflexes are all normal, and there are no rashes. His temperature is 38.7ºC, heart rate 88/min and his blood pressure is 120/80mmHg.

What is the most likely diagnosis?
a