What are the most common cerebral locations of pressure?

Most Common Cerebral Locations of Posterior Reversible Encephalopathy Syndrome (PRES)

The parieto-occipital regions are the most common cerebral locations affected in Posterior Reversible Encephalopathy Syndrome (PRES), with approximately 90% of cases showing involvement of these areas.

Anatomical Distribution of PRES

PRES typically affects specific regions of the brain in a characteristic pattern:

Primary Locations (Most Common)

• Parieto-occipital regions - bilateral and symmetric involvement is the hallmark presentation 1
• Posterior cerebral hemispheres - the defining feature of the syndrome 1

Secondary Locations (Less Common)

• Superior sagittal sinus region - can be affected in more severe cases
• Frontal lobes - involved in approximately 25% of cases
• Temporal lobes - less commonly affected
• Cerebellum - involved in about 30% of cases
• Brainstem - rarely affected
• Basal ganglia - uncommon location

Pathophysiology and Clinical Correlation

The distribution of PRES lesions correlates with the underlying pathophysiology:

• The posterior circulation is more vulnerable due to less sympathetic innervation compared to the anterior circulation, making these vessels more susceptible to sudden changes in blood pressure 1
• When intracranial pressure increases, the parieto-occipital regions are particularly vulnerable due to watershed areas in the posterior cerebral circulation
• The typical radiographic appearance shows vasogenic edema in these regions due to disruption of the blood-brain barrier

Diagnostic Imaging Findings

Imaging is essential for confirming the diagnosis and assessing the extent of involvement:

• MRI is the gold standard for diagnosis, showing hyperintense signals on T2-weighted and FLAIR sequences in the affected regions
• CT may show hypodense lesions in the same distribution but is less sensitive
• The European Society of Ophthalmology recommends OCT as a non-invasive technique that can help detect subtle changes in the optic nerve and retina 2

Clinical Implications

The location of PRES lesions has important clinical implications:

• Visual disturbances are common due to occipital lobe involvement
• Headache is present in nearly 90% of patients due to increased intracranial pressure 1
• Seizures occur in many patients and may be the presenting symptom
• Altered mental status ranges from confusion to coma depending on the extent and severity of involvement

Management Considerations

Management should be tailored based on the extent and location of cerebral involvement:

• Prompt control of blood pressure is essential to prevent progression
• Mannitol (0.5-2 g/kg) may be used to treat increased intracranial pressure in severe cases 2, 3
• Hypertonic saline solution is an alternative for reducing brain edema 1
• Removal of the inciting factor (e.g., immunosuppressive medications) is crucial

Monitoring and Follow-up

Regular monitoring is essential to prevent vision loss and other complications:

• Assessment of visual acuity, pupil examination, and formal visual field assessment should be performed regularly 2
• Follow-up imaging is recommended to document resolution of the lesions
• New or worsening neurological findings should prompt immediate specialist referral 2

The recognition of the characteristic distribution pattern of PRES is crucial for early diagnosis and appropriate management to prevent permanent neurological damage.