Cushing conceptualised the Monro-Kellie doctrine stating that a change in blood, brain or CSF volume resulted in reciprocal changes in one or. Introducción: El trauma craneoencefálico (TCE) es un problema de salud mundial que produce . Doctrina de Monroe-Kelly y de los compartimentos cerebrales. Meanings of “monro-kellie doctrine” in Spanish English Dictionary: 1 result(s) Medicine. 1, Medicine, monro-kellie doctrine · doctrina de monro.
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Cushing conceptualised the Monro-Kellie doctrine kellke that a change in blood, brain or CSF volume resulted in reciprocal changes in one or both of the other two. When not possible, attempts to increase a volume further increase ICP.
However, each volume component may not deserve the equal weighting this static concept implies. The slow production of CSF 0. Neuro-critical care eoctrina focusing on arterial and ICP regulation has been questioned. Failure of venous efferent flow to precisely match arterial afferent flow will yield immediate and dramatic changes in intracranial blood volume and pressure.
Interpreting ICP without interrogating its core drivers may be misleading. Multiple clinical conditions and the cerebral effects of altitude and microgravity relate to imbalances in this dynamic rather than ICP per se. This ekllie reviews the Monro-Kellie doctrine, categorises venous outflow limitation conditions, relates physiological mechanisms to clinical conditions and suggests specific management options.
The Monro-Kellie hypothesis: applications in CSF volume depletion.
Relevant articles were identified by searches of PubMed to Mayand also from the references they quoted. Edinburgh physician Alexander Monro 2 Figure 1 adescribed the skull jellie a rigid structure containing incompressible ee and stated that the volume of monrp must remain constant unless: This description fails to explain the importance of volume flow.
Local pathologist John Abercrombie 4 studied exsanguinated animals and showed that unless the skull and dura were breached, the brain did not exsanguinate in the same way as other organs — the protection the skull offers the brain when ICP is negative to atmospheric pressure often being forgotten.
In none of their accounts, however, did any of this Edinburgh group mention cerebral spinal fluid CSF. In the 16th century, the peers of Vesalius, a Flemish anatomist, rejected his observation that fluid rather than gas or spirit filled the cerebral ventricles.
Interestingly, neuro-critical care practices focusing on arterial and ICP regulation have recently been questioned. The equal weighting to blood and CSF that the static Monro-Kellie doctrine implies, however, misses the dynamic reality.
Many have focused on the role of cerebral arterial flow in neuro-critical care. By demonstrating a correlation coefficient of 0. However, their studies failed to investigate raised ICP secondary to kelkie obstruction. It is well recognised that gentle pressure to the neck over the jugular doctrkna causes an ICP rise.
Monro kellie principle | Blog
Such kelie lack a strong evidence base, 1122 perhaps in part because a single ideal Doctriha is unlikely to exist for all the different forms of brain injury and because increasing CPP also tends to increase ICP. The internal jugular veins are fed from three main intra-cerebral klelie drainage systems Figure 2 a: The dural reflections create a triangular lumen with no muscular wall in marked contrast to the arterial circulation. This makes venous structures more vulnerable to compression.
Obstruction to a dominant sinus has considerably more effect than obstruction to a non-dominant one. Only a small minority of people have significant drainage through the cervical venous plexi 28 which jellie of much greater significance in supine mammals such as swine that have not evolved to the gravitational effects of becoming bipeds. Unlike the strong muscular arterial walls, those of the venous sinuses being triangular dural reflections Figure 2 b are susceptible to dilatation and compression.
In the sitting position, the sagittal sinus has a negative pressure that can result in potentially fatal air embolism if opened.
When supine, bleeding from the sinuses can be torrential. Likewise, when upright, human internal jugular veins tend to collapse under negative pressure, but engorge on lying.
Concentration on arterial inflow, and failure to re the role of venous drainage in ICP regulation, means that much important subtlety is missed: Interpreting the value of regulating Doctrjna, without interrogating its core drivers, may be misleading. In this regard, much historical work has been forgotten. Leonard Hill 8 demonstrated that venous and CSF pressures were aligned and suggested that, given the lack of valves in the cranio-vertebral venous system, vena caval pressure reflected CSF pressure, and retinal venous distension could reflect intracranial venous pressure.
Specifically, increasing central venous pressure CVP results in increasing ICP when compliance is lost, 33 and this in turn results in the formation of brain oedema and swelling. The velocity of blood in the straight sinus and other venous structures, as measured using transcranial Doppler, has been shown to correlate linearly with ICP. Since most neurosurgery today is performed minro general anaesthesia, we are less aware of which intracranial structures are painful.
Ray and Wolff 37 reported multiple observations on up to 30 patient mohro. Again, the pain of venous structures has largely been forgotten. View of a coronal section through the head, showing the falx cerebri, the tentorium cerebelli, and the associated venous sinuses. The full legend is within the figure. Individual susceptibility to intracranial hypertension may thus be influenced by the anatomical balance of cerebral mnro drainage and its compliance. As cerebral blood flow rises, so too must venous drainage.
Venous distension will occur up to a limit, after which intravenous pressure and that upstream, and thus ICP will rise steeply in a similar manner to when the limits of compliance are reached in the classic Monro-Kellie doctrine dee Figure 1.
Anatomical imbalance in venous drainage i. Clinically, this may present with the headache of venous distension when alert or refractory intracranial hypertension if undergoing ICP monitoring.
Within the cranium this can be focal from outside the sinus, within the sinus wall or within the sinus lumen or it can be diffuse compression. Further, venous hypertension can originate in the neck, thorax or abdomen. See Table 1 for a suggested classification with clinical examples.
The thin dural venous sinus walls make them prone to both focal and diffuse compression. Acute compression may result from a depressed skull fracture Figure 4 a or, more commonly, from an expanding mass e. Compression may in turn lead to thrombosis and both may cause intracranial hypertension. It is our experience that occipital skull fractures over the right transverse sinus are more significant since this is the dominant sinus in most people.
Fractures over a hypoplastic sinus rarely have significant effect on ICP. The extradural can be seen compressing and narrowing the dominant right transverse sinus. Note the relatively hypoplastic left transverse sinus. Both left and right scores are summed to give a total CCS. Glomus tumours can have similar effects, although slow growth allows collateral circulation development and the opening of the opposite transverse sinus and cervical plexus.
Treatment depends on how significant the resulting venous compromise is. A conservative management with permissive intracranial hypertension may suffice, although elevating a fracture Figure 4 a or a single burr hole can reduce the mass compressing the sinus and subsequent intracranial hypertension.
Focal transverse sinus stenosis graded as shown in Figure 4 c 41 is associated with idiopathic intracranial hypertension IIH characterised by headache, loss mono peripheral vision and nausea. The additional weight may be contributory to intra-cerebral venous doctrlna through mechanisms III, IV, and V outlined belowtipping a patient that would otherwise be asymptomatic into the decompensated category.
Monro kellie hypothesis | Blog
Ecker 50 described dural sinus thrombosis associated with skull fracture and many more cases have been reported. This group also have impaired pressure reactivity. Treatments have included conservative management, 59 acetazolamide, anticoagulation, 52 ventricularperitoneal VP shunt insertion, 53 endovascular treatment 58 and decompressive craniectomy DC.
In symptomatic cases where there is a depressed skull fracture over the sinus, elevation raising of the depressed bone piece should be considered if there is flow disruption or symptomatic thrombosis.
This can safely be achieved by drilling off just the bone that is holding the fragment depressed and allowing it to rise Figure 4 a. Two of the patients died from associated intra-cerebral lesions. If the thrombosis is progressing and results from an undisplaced fracture then endovascular treatment where available may be considered.
Failure to elevate depressed skull fractures over the sagittal sinus iellie result in IIH.
Diffuse brain swelling can also cause generalised venous compression creating an internal starling type resistor. Recent evidence implies that in many cases of IIH, the entire dural sinus tree appears to minro compressed. This cycle can be broken with CSF drainage although it is likely to recur again, not as CSF accumulates but as venous hypertension recurs. This suggests that functional obstruction of venous outflow through the dural sinuses is present in many IIH doctrkna.
Raised CSF pressure partly obstructs venous sinus outflow, thereby increasing sinus pressure and then CSF pressure, et sequor. It is our experience that a similar phenomenon can occur with other causes of cerebral swelling, such as that resulting from trauma.
Figure 5 is a CT venogram of a patient with diffuse cerebral swelling following trauma which also demonstrates diffuse compression of both transverse sinuses.
A post-operative CT venogram demonstrated marked increase in sinus calibre. CT venograms of a male patient aged year-old male with refractory intracranial hypertension.
Venous pressures can be inferred from brain CT scans. The superior doctrian vein is normally between 1. Neck pressure is well recognised to have a significant effect on ICP. The test comprised jugular venous compression with concurrent lumbar puncture.
Those with spinal stenosis have a slower lumbar pressure CSF rise than those without. The author has modified this technique. By applying pressure over each jugular separately while watching invasively monitored ICP, a crude assessment can be made as to the dominance of venous drainage and the degree of venous compliance. Poor head position is often overlooked but is an incredibly important cause of raised ICP.
Flexion and worse still flexion with rotation caused significant increases in ICP e. This is an even greater problem in children with larger occiputs resulting in flexion and floppier necks. Cervical collars can increase ICP from about 4. These mean pressure increases may be doctria, but they can have profound effects if sustained 79 or if the patient is at the limit of their compliance. As a result, the benefits of cervical collars in the acute management of traumatic brain injury are questionable to say the least.
Positive pressure ventilation in the treatment of chest infection and Adult Respiratory Distress syndrome ARDS can severely raise intra-thoracic pressure as can the application of positive end expiratory pressure PEEP with inter-individual variation in ICP possibly reflecting differences in venous compliance — i. Abdominal compartment syndrome raised intra-abdominal pressure causing organ dysfunction raises ICP in brain-injured patients 89 which can be reduced by decompressive laparotomy DL.
It has also been suggested that the raised intra-abdominal pressures in preeclampsia cause raised cerebral venous and ICPs and contribute to the intracerebral haemorrhage that is sometimes seen.
Figure 6 demonstrates brain herniation occurring as an abdominal wound is closed. This patient who had an acute subdural removed concurrently with a splenectomy for trauma developed acute bleeding from his right transverse sinus and brain herniation as the abdomen was closed, reflecting the rise in venous pressure. Brain herniation occurring at the time of abdominal closure see text