What is basal cistern effacement?
Effacement of the basal cisterns As well as causing mass effect from one side to the other, an intracranial lesion may cause mass effect downwards into the posterior fossa. This may manifest as effacement of the basal cisterns.
What is basal cistern?
The subarachnoid cisterns, or basal cisterns, are compartments within the subarachnoid space where the pia mater and arachnoid membrane are not in close approximation and cerebrospinal fluid (CSF) forms pools or cisterns (Latin: “box”). As they are interconnected, their patency is essential for CSF circulation.
What does midline shift of the brain mean?
A midline shift occurs when the pressure exerted by the buildup of blood and swelling around the damaged brain tissues is powerful enough to push the entire brain off-center. This is considered a medical emergency and is an ominous sign.
What does basilar cisterns are patent?
Arguably, the patency of the basal cisterns is the most commonly used of these signs. Basal cisterns were patent in 51.72% of scans, effaced in 34.48% and obliterated in 13.79%. Even when cisterns were open, more than 40% of scans had at least one episode of ICP ≥ 20 mmHg, and 14% of scans had a mean ICP ≥ 20 mmHg.
What causes Sulcal effacement?
Sulcal effacement is a local secondary sign of mass effect in the cranium. Any lesion exerting mass effect on brain parenchyma can push adjacent gyri together, thereby displacing the CSF from the sulci.
Where are the basal cisterns?
The interpeduncular cistern (or basal cistern) is an unpaired CSF-filled subarachnoid cistern located between the cerebral peduncles. It is partially bounded by the leaves of the Liliequist membrane, one of the arachnoid membranes, which separate it from its direct cranial and caudal relations1.
What is the largest cistern in the brain?
Cisterna magna also called cerebellomedullary cistern – the largest of the subarachnoid cisterns. It lies between the cerebellum and the medulla oblongata. It receives CSF from the fourth ventricle via the median aperture (foramen of Magendie).
Why is a midline shift bad?
Following traumatic brain injury (TBI), midline shift of the brain at the level of the septum pellucidum is often caused by unilateral space-occupying lesions and is associated with increased intracranial pressure and worsened morbidity and mortality.
How much midline shift is significant?
Indications for Surgery. An important reason for operating on a mass lesion is a midline shift of 5 mm or more. Such a shift may be demonstrated by CT scan or occasionally by angiography. Most epidural, subdural, or intracerebral hematomas associated with a midline shift of 5 mm or more are surgically evacuated.
What is arachnoid space?
The subarachnoid space is the interval between the arachnoid membrane and the pia mater. It is occupied by delicate connective tissue trabeculae and intercommunicating channels containing cerebrospinal fluid (CSF) as well as branches of the arteries and veins of the brain.