Pathologies lead to new paths for neurological conditions
Research is blazing a trail through the venous system.
The traditional pathway for treating many cerebrovascular and spinal vascular conditions has been through the arteries. But new research suggests there may be another approach — through the veins.
Nestor Gonzalez, MD, MSCR, FACS, FAHA, professor of neurosurgery and director of the Neurovascular Laboratory at Cedars-Sinai Medical Center in Los Angeles, said the study and advancement of the treatment of these venous pathologies have proven to be somewhat elusive.
“There is less understanding of those conditions and, until recently, not enough work to show the possibilities therapeutic interventions — mainly with endovascular treatments — may have for pathologies or diseases that are derived from the venous system,” he said.
Dena Williams, DO, assistant professor of stroke and vascular neurology at the University of North Carolina School of Medicine in Chapel Hill, North Carolina, said these approaches are rare, and producing enough patients to perform large-scale, randomized trials has been difficult.
“Most of the current data and guidelines are based on consensus and expert opinion,” Dr. Williams said. “The pathophysiology of the cerebral venous system is complex and not perfectly understood, which can make it difficult to study. Often, as is the case in many of these scenarios, associations are identified and then explored further. As we discover more about these associations, they will be evaluated further. A lot of research is being done in regards to the role of endovascular treatment.”
That research will be part of the discussion in Wednesday’s session, Vein Voyage: Advancements in Neurointerventional Treatments and Diagnosis.
Several conditions in which intravenous treatment options are being explored influence a broad spectrum of central nervous pathologies, including intracranial hypertension, intracranial hypotension, fistulas and tinnitus, Dr. Gonzalez said.
With intracranial hypertension, patients may develop elevations in their intracranial pressure with no identifiable cause. In these cases, the answers may be coursing through their veins.
“That condition is known as idiopathic intracranial hypertension and affects numerous patients who have headaches and progressive vision loss, but very often they don’t get properly diagnosed,” Dr. Gonzalez said. “This increase in intracranial pressure can be produced by venous pathologies — for example, a narrowing of the outlets of the veins of the brain. Today, we have a series of possible interventions to determine if that narrowing is significantly associated with the symptoms of a patient with intracranial hypertension and to potentially treat them with the placement of intravascular stents.”
Dr. Williams identified research into the links between cerebral venous pathologies and diseases such as multiple sclerosis and Alzheimer’s disease. However, she cautioned that the research still has a long way to go.
“This is very poorly understood at the current time,” she said. “There is a concept of chronic cerebrospinal venous insufficiency playing a role. The thought is that abnormal venous drainage affects the functioning of the waste clearance from the central nervous system and can result in accumulation of abnormal proteins. However, again much of this is speculative and the precise relationships and how much venous pathology truly plays a significant role in these disease processes is undetermined.”
Dr. Gonzalez said another condition that may be associated with vascular abnormalities in specific cases is tinnitus.
“When the ringing in the ears has a pulsatile character, it may be associated with vascular abnormalities,” he said. “Those vascular abnormalities include abnormal arteriovenous connections and some lesser-known abnormalities of venous origin, including thinning of the bone around the sinuses, persistent large emissary veins — large veins that cross through the bone of the skull — that in many cases are physiological but in some cases may be the reason for the tinnitus and abnormally high jugular location inside of the skull.”
These pathologies are important for physicians to be aware of both in their practice and in a broader scientific sense, Dr. Williams said.
“It is important to recognize these disease entities and their relationship to the venous system in order to provide better clinical care now to our patients as well as to be able to ask more questions and research these relationships further,” she said. “Long term, this will enable us to improve patient care and outcomes.”
Dr. Gonzalez said venous pathologies of the central nervous system have been complex, difficult to study and, until recently, ignored. However, he said that attitude is beginning to change.
“There was not a clear understanding that the cerebral spinal fluid and the veins of the nervous system represent a continuum, and this relationship can cause pathological conditions,” he said. “Intracranial hypotension is another of those conditions where the cerebrospinal fluid can actually leak into these vessels, producing positional headaches that are sometimes very challenging to treat and can significantly affect the quality of life of many patients.
“Today, we have both surgical interventions and endovascular procedures in which cases resistant to the first-line management option — epidural blood patches — can be effectively treated. The better understanding of the anatomy of the veins and the flexibility of new endovascular catheters has allowed us now to specifically navigate to some of these places where the leaks occur and fix them from inside the veins. Another factor contributing to the advancement of these techniques has been an improvement in the quality of the imaging of the brain and the spinal canal that we have today.”
Continued understanding of veins and their contributions could pave the way for better treatment in the years to come, Dr. Gonzalez said.
“Over the years, we have become very familiar with trans-arterial navigation,” he said. “Now, we are embarked on a new frontier, navigating the veins to develop techniques that can significantly impact the treatment of numerous patients.”