📖 AIM Learning Material

An intracranial space-occupying lesion (SOL) is a mass that occupies space within the rigid skull. It may be a tumour, an abscess or another expanding lesion. The skull cannot expand in adults; therefore, increasing mass volume can raise intracranial pressure (ICP), compress nearby brain tissue and eventually cause herniation. A lesion may also cause focal symptoms by damaging a particular functional region.

Clinical classification

• Benign neoplastic: meningioma and some low-grade gliomas. Benign histology does not mean harmless: location, growth and compression determine danger.
• Malignant neoplastic: high-grade glioma, primary CNS lymphoma and brain metastases. These may infiltrate brain tissue or cause extensive surrounding oedema.
• Infective: pyogenic brain abscess and intracranial tuberculoma. Infections may produce focal deficits, seizures and raised ICP.

Useful distinction: A brain abscess contains a collection of pus; a tuberculoma is a granulomatous mass. Imaging can suggest the cause, but a ring-enhancing lesion is not specific for abscess and must be interpreted with clinical context.

AIM VISUAL 01 — Classification of Intracranial Space-Occupying Lesions

Symptoms depend on lesion size, site, rate of growth and associated oedema. Slowly growing masses may present over weeks or months; infection or haemorrhage may produce more rapid deterioration.

Raised intracranial pressure

Progressive headache, vomiting, reduced alertness and papilloedema may occur. Headache can be worse on waking or with coughing. Papilloedema indicates optic disc swelling from raised ICP but may be absent early. Late hypertension, bradycardia and irregular respiration (Cushing response) suggest life-threatening intracranial hypertension.

Focal and generalised features

• Frontal: personality change, executive dysfunction, contralateral weakness.
• Temporal: seizures, memory or language disturbance in the dominant hemisphere.
• Parietal: sensory deficit or neglect.
• Occipital: visual-field defects.
• Cerebellum/posterior fossa: ataxia, imbalance, vomiting and possible obstructive hydrocephalus.
• Other: new-onset seizures, cranial nerve deficits and altered cognition.

Bedside assessment

Establish symptom progression, seizures, fever, recent infection, cancer history, immunosuppression and drug use. Record vital signs, Glasgow Coma Scale (GCS), pupils, limb power, speech, cranial nerves, gait when safe and fundoscopic findings. Falling GCS, unequal pupils, new focal deficit or repeated vomiting requires urgent escalation.

AIM VISUAL 02 — Clinical Presentation and Focused Neurological Assessment

Urgent non-contrast CT head rapidly detects haemorrhage, significant mass effect, hydrocephalus and midline shift, especially in unstable patients. MRI brain with contrast better characterises many tumours, posterior fossa lesions and infection when the patient is stable and imaging is available.

• Mass effect: compression of ventricles or displacement of the midline suggests pressure on adjacent structures.
• Vasogenic oedema: surrounding brain swelling contributes to symptoms and raised ICP.
• Contrast enhancement: reflects altered blood–brain barrier or vascularity; patterns are suggestive, not definitive.
• Hydrocephalus: enlarged ventricles from impaired CSF flow, particularly with posterior fossa lesions.
• Abscess: may show a ring-enhancing lesion with surrounding oedema; MRI diffusion restriction can support the diagnosis.

Imaging is interpreted alongside history and examination. Histopathology or microbiology may be needed for definitive diagnosis, selected by the specialist team. Do not perform lumbar puncture when a mass lesion with significant raised ICP or herniation risk is suspected; seek urgent imaging and specialist advice.

AIM VISUAL 03 — Neuroimaging and Diagnostic Interpretation

Initial priorities are airway, breathing, circulation, neurological monitoring and urgent neurosurgical assessment. Support oxygenation and perfusion, elevate the head when appropriate, avoid hypotension and treat seizures. Deteriorating consciousness, herniation signs or obstructive hydrocephalus demand emergency escalation. In acute neurological deterioration from severe raised intracranial pressure, emergency measures may include hyperosmolar therapy with IV mannitol or hypertonic saline under specialist supervision while definitive treatment is arranged. Obstructive hydrocephalus may require urgent external ventricular drainage. These interventions must not delay neurosurgical management.

Cause-directed treatment

• Benign tumour: observation with interval imaging for selected stable lesions, or surgery when symptomatic, enlarging or compressive.
• Malignant tumour: specialist assessment for maximal safe resection or biopsy, followed by radiotherapy and/or systemic treatment depending on pathology.
• Brain abscess: prolonged appropriate intravenous antimicrobial therapy and, when indicated, neurosurgical aspiration or drainage.
• Tuberculoma: antituberculous treatment according to the treating team, with monitoring of clinical and radiological response.

Dexamethasone may reduce symptomatic vasogenic oedema around selected tumours; it is not routine for every SOL and is not a substitute for treating the cause. Antiseizure medicines are used for documented seizures or specific specialist indications rather than indiscriminately for every lesion. Surgical decisions depend on accessibility, diagnosis, mass effect, functional risk and patient condition.

AIM VISUAL 04 — Management of Intracranial Space-Occupying Lesions

Macrocephaly means an occipitofrontal head circumference above the 97th percentile (more than 2 standard deviations above the mean) for age and sex. A large head is a finding, not a diagnosis. Serial measurements and growth velocity matter more than a single reading.

Important causes

• Familial benign macrocephaly: normal development, normal examination and large parental head circumference.
• Hydrocephalus: increased CSF within the ventricles due to obstruction or impaired absorption; may cause progressive head enlargement in infants.
• Benign enlargement of subarachnoid spaces: typically in otherwise well infants, diagnosed with clinical and imaging correlation.
• Intracranial mass or subdural collection: may increase head size or cause pressure signs.
• Other causes: megalencephaly or selected metabolic/genetic conditions, especially when development is abnormal.

History and examination

Plot head circumference on age- and sex-appropriate growth charts and compare previous values. Ask about family head size, pregnancy/birth history, vomiting, feeding, irritability, milestones, seizures and trauma. Examine fontanelle tension, scalp veins, eye position (including sunsetting eyes), tone, reflexes, development and signs of raised ICP.

Investigation and management

A well child with proportionate familial head size, normal development and stable growth may need observation and follow-up. Rapid crossing of centiles, bulging fontanelle, vomiting, lethargy, seizures or developmental regression requires urgent assessment. Cranial ultrasound is useful through an open fontanelle; MRI gives anatomical detail, while CT is reserved for urgent indications because of radiation. Treatment targets the cause: hydrocephalus may require neurosurgical CSF diversion, whereas benign cases need reassurance and growth/development monitoring.

 

Head injury ranges from concussion to intracranial haemorrhage and severe traumatic brain injury (TBI). Primary injury occurs at impact; secondary injury develops through hypoxia, hypotension, swelling and raised ICP. Early care aims to prevent secondary brain injury.

Initial trauma approach

Use an ABCDE assessment with cervical-spine protection. Secure airway and oxygenation when necessary, control external bleeding, maintain circulation and check capillary glucose. Record GCS components, pupil size/reactivity, limb movement, seizures and vital signs; repeat observations because deterioration may be delayed.

Severity and imaging

GCS 13–15 indicates mild, 9–12 moderate and 3–8 severe TBI after initial stabilisation. Urgent CT is indicated for concerning features such as depressed consciousness, focal neurological deficit, suspected skull fracture, repeated vomiting, post-traumatic seizure or other validated head-injury risk criteria. A normal initial CT does not replace observation when symptoms or risk factors remain concerning.

Common intracranial injuries

• Epidural haematoma: classically biconvex/lens-shaped extra-axial collection, often related to skull fracture; may deteriorate rapidly.
• Subdural haematoma: crescent-shaped extra-axial collection, often due to bridging-vein injury.
• Contusion/intraparenchymal bleed: focal bruising or haemorrhage within brain tissue.
• Diffuse axonal injury: widespread shearing injury; severe impaired consciousness may occur despite relatively subtle CT findings.

Management principles

Mild uncomplicated injury may be managed with observation, clear return precautions and graded return to activity. Moderate or severe injury requires hospital care, frequent neurological review and specialist involvement. Significant haematoma, mass effect, depressed fracture or refractory raised ICP may require neurosurgical intervention. Avoid hypoxia, hypotension and unnecessary delays in referral.

AIM VISUAL 06 — Head Injury: Initial Assessment, Imaging and Treatment

After head-injury surgery, monitor neurological status, airway, oxygenation, blood pressure, temperature, fluid balance and wound condition. Watch for falling GCS, new weakness, worsening headache, repeated vomiting, seizures, fever, wound discharge or clear fluid leakage. These can indicate bleeding, raised ICP, infection or CSF leak and need immediate medical review. Explain to the family in clear language what injury occurred, why surgery was needed, what recovery may involve and why serial examinations and repeat imaging are sometimes necessary. Discuss medicines and follow-up as prescribed, wound care, seizure precautions where indicated and rehabilitation for weakness, speech, memory or behaviour problems. Discharge safety: provide written advice on red flags; avoid driving, hazardous work or sports until medically cleared; encourage gradual activity and supervised recovery. A patient may have persistent cognitive, emotional or physical symptoms despite a healed wound. Arrange neurosurgical review and rehabilitation support when indicated, and include the patient in decisions whenever capacity allows.

AIM VISUAL 07 — Postoperative Care, Family Counselling and Follow-Up

Feature	Epidural haematoma	Subdural haematoma
Typical vessel	Often arterial	Often bridging veins
CT appearance	Biconvex / lens-shaped	Crescent-shaped
Clinical concern	Rapid deterioration possible	Acute or delayed deterioration