Cisternostomy

Cisternostomy is a neurosurgical procedure which uses skull base and microvascular techniques to access and open the basal subarachnoid cisterns and reverse the brain swelling in moderate to severe head trauma.
In head injuries, the principle of “CSF-Shift Edema” plays the pathophysiological role in increasing the intracranial, or more precisely, the intra-parenchymal pressure as a consequence of traumatic subarachnoid hemorrhage. Cisternostomy reverses the “CSF-Shift” by opening the cisterns to atmospheric pressure, hence reversing the pressure gradient that caused the cerebrospinal fluid (CSF) to shift into the brain parenchyma through the Virchow Robin Spaces.
Unlike Decompressive craniectomy, Cisternostomy avoids the risks associated with bone flap removal and cranioplasty as well as the displacement of the swollen brain to the craniectomy defect resulting in extensive damage to tracts and axons due to stretch.
The procedure accesses the basal cisterns through the axial and sagittal unlocking of the frontal and temporal lobes by drilling off the sphenoid ridge and dissection of the orbito-meningeal band. The dura is opened at the base and the blood is washed out following dissection of the optico-carotid cister. The carotico-oculomotor cistern is opened. The opticocarotid cistern is opened and the blood is washed out, the carotico-oculomotor cistern is opened. Dissection of the Liliequest membrane leads to the cisterns of the posterior fossa. A feeding tube is inserted into the prepontine cistern and kept for five days to drain CSF.
The entire procedure takes about ten to twenty minutes to complete post learning curve. The learning curve to reach the basal cisterns in exceedingly swollen brain is important as many neurosurgeons find it difficult to retract a swollen brain. However, once the cisterns are reached even with some retraction damage to the orbitofrontal gyri, the brain starts getting lax. Cisternostomy is increasingly being regarded as a more efficient and effective primary surgical intervention for moderate to severe TBI. Its potential application is highly due to its immediate effect in lowering intracranial pressure (ICP) and its role in the improvement of brain oxygenation and metabolism.
Severe head trauma results in subarachnoid hemorrhage. This results in blood entering the cisterns at a relatively higher pressure and this results in increased pressure within the cisterns.
The increase in pressure within the cisterns results in a gradient that pushes the CSF from the cisterns into the brain parenchyma. This is the basis of CSF shift edema and this has been proven with animal experiements by Dr. Garnette Surtherland
At this point, the skull drilling stops and the dura is carefully detached from the bone.
This maneuver allows one to get to the base very close to the cisterns. The basal dura is opened in a linear fashion near the orbital roof. This maneuver allows easy (and sometimes rather difficult) access to the interoptic, optico-carotid and the lateral carotid cisterns that can now be opened for draining. Cerebrospinal outflow immediately provides brain relaxation which enables further reaching the membrane of Liliequist.
The membrane of Liliequist can be approached through the optico-carotid window or the lateral carotid window. The membrane, made up of two layers, can be opened by a sharp dissection. After the membrane is widely opened, the basilar quad consisting of the basilar artery, both P1 segments, the superior cerebellar arteries and the Occulomotor nerve on both sides is visualized. Timing of intervention is an important indicator of Cisternostomy as the primary surgical management in moderate to severe brain injury. The rationale of Cisternostomy based on the reversal of CSF-Shift edema is applicable when there are clinico-radiological signs of raised ICP and imminent transtentorial herniation. According to a clinical study, the deterioration of motor score on the Glasgow Coma Scale from 5 to 4, with associated radiological sign of ipsilateral cerebello-pontine angle (CPA) cistern widening, warrants immediate Cisternostomy to prevent the ongoing herniation.
Outcomes following Cisternostomy in moderate to severe brain injury have been remarkable till date. The current studies and reports from centers performing Cistenrostomy have well-established the efficacy of this procedure in playing a two-fold role by decreasing ICP and preventing progression to secondary brain injury.
Various studies have observed the following outcomes post cisternostomy:
* Normalization of intracranial pressure (ICP)
The similar effect was observed when the cisterns were opened serendipitously assuming an aneurysm repair rather than a traumatic brain by Dr. Iype Cherian during his practice in India. The surprisingly significant brain laxity observed led to further clinical observations, with the initial years of performing a hybrid Cisternostomy with bone flap removal, and a considerably improved prognosis in patients.
Cisternostomy and the manoeuvres to access the skull base have been routinely practised in neurosurgery for skull base tumours and aneurysms. However, when introduced as a primary surgical procedure for traumatic brain injury, this faced significant challenges in terms of acceptance. There is a reluctance to adopt a change in the current practice of DHC regardless of the rising mortality and vegetative states it leads to. Over the course of a decade with evidently positive prognosis in some centres in India, Nepal, China and parts of Europe have created waves in the field of neurotraumatology. Comparative studies to assess the prognostic value of Cisternostomy over DHC have clearly shown that opening the basal cisterns in a traumatic brain instantly reduces the brain edema. Furthermore, the replacement of the bone flap back in a single procedure prevents the cortical stretch which otherwise alters the topography of the motor and sensory cortices of the brain that leads to hemiplegia and other forms of morbidity seen in patients undergoing DC Further studies are also evaluating the recognition of Cisternostomy as a protocol for emergency neurotrauma provided the available expertise and instruments is available. An on-going neurotrauma study, Global Neurotrauma Outcomes Study funded by the NIHR regards cisternostomy as one of the techniques vital to the reduction of ICP in emergency TBI. Other trials and studies to evaluate alternate surgical options for moderate to severe TBI are based on the principles of a single-staged surgery, preventing decompression as much as possible for a positive outcome.

Main Menu

See Also

Main Menu