QuestionSBA
QuestionChoice
The occipital lobe is involved in visuospatial processing, colour perception and facial recognition. It is not involved in the gag reflex. Occipital lobe damage may present with the above features, alongside a visual field defect of contralateral homonymous hemianopia with macular sparing.
52856
e
Occipital lobe
QuestionChoice
The midbrain may be damaged as a consequence of head injury; however, the nuclei of CN IX and X are found in the medulla, not the midbrain. The midbrain contains the nuclei of CN III and IV. These are not involved in the gag reflex.
52854
c
Midbrain
QuestionChoice
Skull fractures sustained during head injury can be a risk factor for septic cavernous sinus thrombosis. However, in this scenario, there is no fracture (the CT head is normal) and no clinical features of a septic cavernous sinus thrombosis, including involvement of nerves III, IV, Va, Vb and VI, which run through the cavernous sinus.
52855
d
Cavernous sinus
QuestionChoice
The pons may be damaged as a consequence of head injury; however, the nuclei of CN IX and X are found in the medulla, not the pons. The pons contains the nuclei of CN V, VI, VII and VIII. These are not involved in the gag reflex.
52853
b
Pons
QuestionChoice
The gag reflex is an evolutionary reflex with the primary role being to prevent foreign body inhalation. This reflex is made up of the glossopharyngeal nerve (CN IX) as the afferent limb and the vagus nerve (CN X) as the efferent. These two nerves have their nuclei in the brainstem medulla, alongside CN XI and XII. Compression may be as a result of raised intracranial pressure secondary to injury, given that no focal abnormalities were noted on his head scan.
52852
a
Medulla oblongata
QuestionComment
Stolen from another question:

Midbrain CN 1,2,3,4
Pons CN 5,6,7,8
Medulla CN 9,10,11,12
24142
User
subscriber
Supine Body
QuestionComment
Was anyone else completely humbled by this mock
53259
User
subscriber
Claire
Concept
Chapter
# Summary

Raised intracranial pressure (ICP) can result from various underlying causes and presents with a range of symptoms. Concerning features include **headaches**, particularly those worse in the morning or with bending over, **visual disturbances**, **nausea and vomiting**, and **focal neurological deficits**. Additional worrying signs related to the underlying cause include **weight loss** and **night sweats**. Prompt recognition and management are essential to prevent serious complications like **seizures**, **reduced Glasgow Coma Scale (GCS)**, and potentially fatal outcomes such as **brain herniation (coning)** and death.

# Definition

Raised ICP refers to increased pressure within the skull, which can lead to brain damage and death if left untreated. The **Monro-Kellie Doctrine** explains that the skull is a fixed volume, and any increase in the volume of brain tissue, blood, or cerebrospinal fluid (CSF) must be compensated for by a decrease in another component to maintain normal pressure. Failure to compensate leads to elevated ICP, increasing the risk of **coning** (herniation of brain tissue) and **brainstem death**.

# Aetiology

The causes of raised ICP are varied and can be classified using the **VITAMIN C DEF** mnemonic:

- **V**ascular: Stroke, intracranial hemorrhage (subdural, epidural, subarachnoid).
- **I**nfective: Meningitis, encephalitis, brain abscess.
- **T**rauma: Traumatic brain injury.
- **A**utoimmune: Vasculitis.
- **M**etabolic: Hepatic encephalopathy, hypercapnia.
- **I**atrogenic: Post-surgical or procedural complications.
- **N**eoplastic: Primary or metastatic brain tumors.
- **C**ongenital: Hydrocephalus.
- **D**egenerative: Normal pressure hydrocephalus (in elderly patients).
- **E**ndocrine: Pituitary adenoma, hypothyroidism (myxedema coma).
- **F**unctional: Idiopathic intracranial hypertension (IIH).

# Symptoms and Signs

## Symptoms

- **Headaches**: Worse in the morning, with coughing, straining, or bending over.
- **Nausea and vomiting**: Often early signs of raised ICP.
- **Visual disturbances**: Blurred vision, diplopia, or papilledema (swelling of the optic disc).
- **Seizures**: May occur as ICP rises.
- **Focal neurological deficits**: Varies depending on the underlying cause (e.g., weakness, sensory changes).

## Signs

- **Cranial nerve involvement**: 
  - **Abducens nerve (CN VI)** is most vulnerable due to its long course, leading to **lateral gaze palsy**.
  - **Third cranial nerve palsy** (uncal herniation): Ptosis, fixed dilated pupil, and eye deviation.
- **Cushing’s triad**: A late sign of impending brain herniation, includes:
  - **Bradycardia**.
  - **Hypertension**.
  - **Irregular breathing**.

# Investigations

## Clinical assessment

- **History and examination**: Look for signs of raised ICP and focal neurological deficits.
- **Observations**: Watch for **Cushing’s triad** as a sign of impending coning.

## Blood tests

- Focus on identifying the underlying cause (e.g., infection, metabolic derangements).

## Neuroimaging

- **CT head (CTH)**: First-line imaging to assess for mass lesions, hemorrhage, or hydrocephalus.
- **MRI**: May be used for further characterization of lesions or if clinical suspicion remains despite normal CT findings.

# Management

## Initial Assessment
Management begins with a standardized **ABCDE approach**:

- **Airway, Breathing, Circulation**: Ensure airway patency and adequate oxygenation.
- **Disability**: Assess using the **Glasgow Coma Scale (GCS)**.
- **Exposure**: Check for signs of trauma, infection, or other causes of raised ICP.

# Medical Management

1. **Seizure management**: Detect and treat seizures with **anticonvulsants** as per the **status epilepticus protocol**.
2. **Positioning**: Elevate the bed to **30-40 degrees** to facilitate venous drainage and reduce ICP.
3. **Sedation and airway protection**: If **GCS < 8**, consult an **anesthetist** for airway management.
4. **Hyperosmolar therapy**: 
   - **Hypertonic saline** is preferred for reducing ICP through osmotic effects.
   - **Mannitol** may also be used, but carries risks such as **unpredictable pharmacokinetics** and potential **anaphylaxis**.
5. **Control of underlying cause**: Treat infection (e.g., antibiotics for meningitis), control metabolic derangements, or manage systemic conditions contributing to raised ICP.

# Surgical Management

1. **Neurosurgical referral**: If the cause is a mass lesion, intracranial hemorrhage, or hydrocephalus, neurosurgical input is required.
2. **Definitive interventions**: These may include:
   - **Decompressive craniectomy** to relieve pressure.
   - **Ventriculostomy** or **ventriculoperitoneal (VP) shunt** for drainage of CSF in cases of hydrocephalus.

# Monitoring and Follow-Up

- Continuous monitoring of **GCS** and **ICP** is critical.
- Regular neuroimaging may be required to assess the progression of the underlying cause and response to treatment.


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Raised intracranial pressure
Topic
34
Neurology
10631
Lesions in the medulla oblongata can impair the gag reflex, indicating potential brainstem injury or raised intracranial pressure.
A 32-year-old man is brought in by ambulance to A&E after a road traffic collision. On examination, he has a large wound at the back of his head. His Glasgow Coma Score is 3. A CT scan of the head shows no abnormalities. A rapid sequence induction of anaesthetic is performed to secure his airway. A week into his admission, extubation is attempted on the Intensive Care Unit but this is unsuccessful. A gag reflex is documented as being absent in his medical notes.

Where is the lesion causing his clinical presentation?
a