Overview of Nasoseptal Flap
The nasoseptal flap technique has significantly improved the way surgeons repair the front part of the skull base, which is basically the floor of the brain. Before this method was introduced in 2006, doctors would use other tissue flaps from the head. However, these could create unnecessary complications or harm for patients.
It’s important to remember that not all skull base repairs require a tissue flap with its own blood supply. Often doctors can use grafts, which are like patches made from the patient’s own tissue or synthetic material. But for large skull base defects where there is a high-flow cerebrospinal fluid leak (the protective fluid around the brain and spinal cord is leaking), doctors usually need a tissue flap with its own blood supply to avoid a post-surgery leakage of cerebrospinal fluid. This could lead to complications.
The nasoseptal flap is a piece of tissue from inside the nose that has its own blood supply. This reduces the risk of complications and increases the chances of a successful surgery for the front part of the skull base.
This technique, also known as the Hadad-Bassagasteguy flap (HB flap), was developed in Argentina and the United States. Since its initial introduction in 2006, there have been numerous proposals on how to enhance and expand its use.
Anatomy and Physiology of Nasoseptal Flap
The nasal septum is the central support for the nose and the nasal cavity. There are four major parts of the nasal septum: the maxillary crest, the vomer, the perpendicular plate of the ethmoid bone, and a rectangular piece of cartilage. The cartilage and bone parts of the septum are covered with special membranes, and the whole septum is lined with a type of skin called mucosa. The mucosa has a strong blood supply and is made up of a certain type of cell. Much of the blood supply comes from arteries such as the sphenopalatine, posterior septal, and greater palatine arteries, as well as contributions from a few others.
The nasoseptal flap is a piece of tissue in the nasal septum that is supplied by the nasoseptal artery, a branch of the posterior septal artery. Child and adult nasoseptal flaps can have different sizes in length and width. The standard nasoseptal flap is bordered by the edges of the nasal septum. Sometimes, changes can be made to the nasoseptal flap, such as adding more tissue. This is often done to repair large defects at the base of the skull by including tissue from the nasal floor and possibly the side wall of the nose.
When the mucosa and other membrane are lifted off the cartilage and bone parts of the septum, the exposed areas of the nasal septum can regrow the mucosa as long as the other side is intact. The topmost part of the nasal septum not only moistens and lines the nasal cavity but also helps in the sense of smell. The top 1 to 2 cm of the nasal septum’s mucosa are smell receptors and contain nerves of the first cranial nerve. The lower portion of the septum has a small indentation often seen in many patients, known as vomeronasal organ or Jacobson’s organ. There’s debate about what this organ does, but many believe it to be an organ that’s no longer needed with no clear use.
Why do People Need Nasoseptal Flap
In the past, a medical procedure involving a ‘nasoseptal flap’ was commonly used to repair large defects in the bones and the tough outermost membrane covering the brain and spinal cord (known as the ‘dura’) towards the front of the base of the skull, following surgery in this area. Essentially, this procedure uses a flap of tissue from the divider between the nostrils (i.e., the nasoseptal area) to cover and heal the areas where surgery was performed.
Over the past twenty years, doctors have started to use this nasoseptal flap method for other conditions as well, and they are currently studying how effective these new uses are.
The nasoseptal flap can cover a large area in skull base surgeries, extending from the ‘cribriform’ (an area at the roof of the nasal cavity) to the ‘clivus’ (an area towards the back of the skull base). Recent research has looked at using the nasoseptal flap method to repair the nasal cavity and skull base, as well as the mouth and throat (or ‘oropharynx’) after certain types of robotic surgery. In these cases, the nasoseptal flap has been guided through the roof of the mouth to repair soft tissue defects in regions around the lower jawbone, a major artery called the internal carotid artery (ICA), and as far back in the throat as the vallecula (a part of the throat at the back of the tongue).
When a Person Should Avoid Nasoseptal Flap
There are times when using a nasoseptal flap, a kind of skin graft from inside the nose, may not be the best option or may not work at all for some patients. For example, if the patient has a large tumor inside the nose that has spread to the inner wall of the nose or to the sphenopalatine artery, which supplies blood to the nasal cavity, the nasoseptal flap might not work. Also, previous surgeries like removing the rear part of the nasal septum, surgery on the sphenoid sinus, or tying off the SPA could mean that using a nasoseptal flap isn’t a good idea.
Interestingly, a past uncomplicated septoplasty, which is a surgery to fix a deviated septum, doesn’t usually prevent the use of a nasoseptal flap. If a nasoseptal flap from the same side as the problem isn’t suitable, often a nasoseptal flap from the other side of the nose can be used instead.
If a nasoseptal flap can’t be used at all, there are other options your doctor may consider. These include flaps from the lower or middle part of the structures inside your nose. They might also use a flap from the side of your head near your ear, from the soft tissue that covers the outer layer of the skull, from the roof of your mouth, or from other parts of your body for bigger defects.
Equipment used for Nasoseptal Flap
Certain tools and setup specifics come down to what the surgeon prefers to use, but the procedure is usually done using standard equipment. The operating room should be organized as it typically is for standard procedures dealing with the sinuses or base of the skull. Total intravenous anesthesia (TIVA), which is when all the anesthesia is given through an IV, can be used if okayed by the anesthesia provider. It can lead to clearer visuals during the operation. The patient can be positioned lying down facing upwards at an inclined angle to help minimize blood loss and provide a clean area to operate on.
Even though there should be various types of endoscopes (instruments used to view inside the body) available, typically the surgeon will use either a 0 or 30-degree endoscope to look while lifting the flap of tissue. A tool called an ‘endoscopic monopolar electrocautery’ instrument helps make clean, precise incisions while controlling bleeding at the same time. Other tools that are typically used, and are usually found already in the basic setup for sinus surgery, are: Cottle elevator, micro-scissor, ball-tip probe, curette, curved olive-tip suction, and different types of forceps for cutting and handling tissue. These assist the surgeon to delicately lift and shape the tissue flap.
Various materials, either man-made, from the patient or from a donor, can be used to place under the tissue flap and help it stay secure in its new position. Artificial dura mater (a protective layer of tissue), the patient’s own fat and fascia (fibrous tissues), along with absorbable material that helps support the flap can all be used. Gauze or a type of inflatable instrument might be used to help keep the graft (the implanted tissues/materials) and additional material stable as the patient recovers from surgery. It’s worth noting though, that the choice of these materials often depends on the surgeon’s preference.
Who is needed to perform Nasoseptal Flap?
Carrying out a successful nasoseptal flap procedure requires a well-prepared and experienced medical team. This team often includes a circulating nurse, who helps out in the operating room, a scrub technician that assists the surgeon, a doctor who gives anesthesia (medicine that blocks pain), and a surgeon with expertise in nasal and skull base operations. Usually, this procedure is carried out by a specialist, known as an otolaryngologist, who has received extra training in nose-related and skull base surgeries. However, many brain surgeons (neurosurgeons) have the required skill and training to perform the procedure successfully.
The leading surgeon, assistant surgeon, or consulting surgeon can change depending on the specific case, location or hospital rules. Also, if the planned process involves using various materials, experts knowledgeable about the usage and limitations of these materials should be available physically or virtually. This is to make sure that the materials are used correctly and safely.
Preparing for Nasoseptal Flap
Before doctors start creating a nasoseptal flap, they need to understand your medical history and conduct a physical examination. This might include using an instrument to look inside your nose, a process known as an endoscopic nasal exam. The doctor will ask you about any current health problems you have, why you need the surgery, and if you have ever had any nose-related operations before.
They will check your head, neck, and inside your nose to see if there are any issues that might affect the surgery. These issues can include things like previous operations, a deviated septum, holes in the septum, or unusual skin lesions. If your septum is part of a tumor, this might also determine how the reconstruction is done.
Imaging exams, such as CT scans or MRIs, help doctors prepare for the surgery by providing them with detailed images of your sinuses, the base of your skull (where your brain rests), or other areas in your head. These exams can help them identify potential challenges that could arise during the surgery. You should stop using all nasal drugs and avoid anything, including new piercings, that could hurt your septum before the surgery.
Since this type of surgery involves areas that already contain bacteria, there is no need to sterilize the inside or outside of your nose beforehand. However, it may be necessary to trim the hairs in your nose to prevent any buildup of blood or secretions that could interfere with the scope used during the procedure and cause complications during the surgery. They’ll also take appropriate steps to make sure that your body is positioned correctly for the operation.
How is Nasoseptal Flap performed
Firstly, the procedure would start by giving you nasal decongestant medicine to unclog your nose. To numb the area we’ll operate, we’ll give you a local anesthetic inside your nose on the side we’ll be working on. To work effectively, we need good access and space, so we will move some structures inside your nose called “turbinates” to the sides. We need to measure the area where we will work and plan out a flap of tissue from your nasal septum (the divider between your nostrils).
We have to be careful not to damage the part of your nose that helps you smell things when we take out the tissue. So, we may draw on the tissue flap with a skin marker before cutting it, to help us remember where everything goes. The cuts for the flap are made in a specific pattern to ensure good blood flow in the flap.
Once we’ve made sure all the cuts are complete, we lift the flap using special instruments and start from the front and bottom. We have to be very careful while doing this to avoid injuring the blood supply to the flap. When lifted, the flap is tucked away safely, most commonly in the nasopharynx (the part of your throat that’s behind your nasal cavity) so it’s not in the way. Later in the procedure, we can get it out and put it back carefully in its correct orientation.
Next, based on the specifics of your case and surgeon’s preference, we rebuild the defect using a variety of materials, including tissue from you, synthetic materials, and other types of surgical flaps. We then put the nasal septal flap we created earlier into the defect and support it with a special medical gauze or a balloon-like device. However, we have to be careful not to inflate the balloon too much, or it can move the flap out of place.
We could also use a flap from the other side of your nasal septum to cover the area where we took the first flap, decreasing the discomfort you might feel from the procedure. However, by using this strategy, it means we’ve used up both flaps and will have to consider other options for any future procedures.
Possible Complications of Nasoseptal Flap
The nasoseptal flap, a type of surgery often used for skull reconstruction, is generally well-accepted within the surgical field due to its wide range of uses, high success rates, and few complications. Initial concerns about its use in children have been resolved, and it’s considered a safe option for skull reconstruction, without negatively affecting facial growth.
Generally, complications from the nasoseptal flap surgery are rare. In a case study with 44 patients, doctors Hadad and Bassagasteguy reported very few issues. One patient had a cerebrospinal fluid (CSF) leak (that’s when fluid around the brain and spinal cord leaks out), another had nosebleeds that required treatment, and a few patients developed symptom-free synechiae, which means sticking together of two bodily surfaces that are usually separate. However, the CSF leak was treated successfully in all cases, and the septum (the part of the nose that separates your nostrils) healed properly without any holes forming.
A study from Australia wanted to see if the quality of life changed after a nasoseptal flap surgery. It found that people had a temporary decrease in their nasal function and quality of life (based on different medical tests). They also reported increased ear pain and a reduced sense of smell compared to those who had different kinds of skull reconstruction. However, these symptoms and reduced scores got better by six weeks after surgery, showing no long-term issues in patients who underwent the nasoseptal flap surgery. Other studies suggested a mild reduced sense of smell persisted for up to six months after surgery.
What Else Should I Know About Nasoseptal Flap?
In 2006, Hadad and Bassagasteguy introduced an important technique in brain surgeries involving the front part of the skull. This technique, called the nasoseptal flap, has become a vital tool for surgeons specialized in operations involving the skull base, often referred to as endoscopic skull base surgeons. The technique utilizes a part of the nasal septum, the wall dividing the nasal cavity, to rebuild or repair the area under surgery.
Using the nasoseptal flap significantly lowers risks for patients. It avoids the need for more complicated procedures, such as using tissue from other parts of the body (free flap reconstruction) or making incisions on the face or head (external approaches).
One of the main advantages of the nasoseptal flap has been its effect on reducing a problem known as cerebrospinal fluid (CSF) leakage. In the early days of minimally invasive nose-based operations (Endoscopic Endonasal Approach or EEA), the risk of CSF leaking was up to 24%. But thanks to the nasoseptal flap technique, that risk has dropped to as low as 3%.
The uses of the nasoseptal flap are continuously expanding as more surgeons appreciate its benefits. It is highly versatile and can potentially be used for reconstructing the palate (roof of the mouth) and pharynx (part of the throat), in combination with other local tissue flaps. These potential applications are yet to be fully explored.
