Overview of Mucous Membrane Graft
The conjunctiva is an important part of our eyes. It’s a clear layer of tissue covering the front of our eyeballs and the insides of our eyelids. This layer is actually quite complex, containing multiple types of cells and structures including lymph and blood channels, fibrous tissue, accessory tear glands, and others. One special type of cell in the conjunctiva, known as a goblet cell, produces a mucus-like substance that helps keep our eyes moist and protected. By helping produce tears and providing physical protection, our conjunctiva plays an essential role in our eye health.
Unfortunately, injury or disease can sometimes cause harm to the conjunctiva, resulting in problems like dryness, vision issues, or incorrectly positioned eyelids. If the conjunctiva gets damaged, doctors will try to replace it with similar tissues. Sometimes, they’ll use parts of the amniotic membrane (the lining of the womb), a piece of the hard palate (the roof of the mouth), nasal septal mucosa (lining of the nose), or other materials. However, these replacements can be challenging to obtain or limited in availability.
For this reason, doctors often turn to grafting (transplanting) a piece of oral mucosa (tissue from inside the mouth) to replace the damaged conjunctiva. This method has several benefits:
– Similarity: Oral mucosa has biological properties that are close to those of the conjunctiva.
– Accessibility and abundance: The inside of the mouth is easy to reach, and there’s plenty of tissue to use.
– Ease and affordability: Removing a piece of the oral mucosa is simple and inexpensive.
– Few complications: Problems following this type of graft are rare.
– Reharvesting: If needed, doctors can repeat the process.
– Autografting: Because the graft is from your body, there’s no risk of rejection.
This technique was first introduced in 1912 to treat lime burns and has since found use in treating several eye conditions including: after removal of pterygia (a growth on the eye), to fix contracted-eye sockets, for reconstruction after tumour resection, for various eyelid deformities, for repair of erosions over eye drainage devices, support of keratoprosthesis (artificial corneas) associated with corneal melt, and more. It’s important to note, though, that oral mucosa does not contain goblet cells and so cannot help dry eyes unless transplanted with minor salivary glands (the glands that produce saliva). Also, if a patient has a large deficiency of limbal stem cells (cells that help regenerate the cornea), a stem cell transplant procedure may have to be performed simultaneously. Despite these considerations, the oral mucosal membrane remains a valuable resource in eye care due to its resilience, high vascular nature (lots of blood vessels), and compatibility.
Anatomy and Physiology of Mucous Membrane Graft
The mouth is a complex structure with many different parts, all of which serve different functions. Two of these parts are the buccal mucosa (the inner cheek) and mandibular labial mucosa (the lower lip), both of which have special properties.
The buccal mucosa and mandibular labial mucosa can be thought of as a patch of smooth, moist skin. This area is bounded by the corners of the mouth, the base of the mouth, and the folds of skin that line the upper and lower jaws.
These sites have a rich blood supply, provided by the maxillary artery, which branches out to provide blood to the rest of the mouth. Other arteries, such as the infraorbital artery and the superficial temporal artery, also contribute to the blood flow.
The long buccal nerve, which is a branch of a larger nerve called the trigeminal nerve, provides a sense of touch to the buccal mucosa. Other branches of the trigeminal nerve and the facial nerve also play roles in sensation.
The structure of this skin is made up of several layers, with the topmost layer being a type of cell called stratified non-keratinized squamous epithelium. Beneath this layer is a network of blood vessels embedded in a layer of connective tissue. There are also layers that contain salivary glands. These glands produce saliva that helps us with digestion.
One unique property of the mouth is the presence of a layer called the oral mucosa. This layer is exceptionally durable and flexible, allowing it to resist damage. It’s also rich in blood vessels and nerve fibers, contributing to the mouth’s sensitivity. This resilience and adaptability make the oral mucosa an excellent choice for certain types of medical procedures, like mucous membrane grafts.
Moreover, the inside mouth skin is remarkable at defending itself against disease-causing microorganisms, thanks to various antimicrobial substances it secretes. It also has a high number of immune cells to help fight off any potential infections.
Interestingly, there are also some similarities between the mouth’s physiological functions and those of our eyes. Both areas produce a substance called mucin, which helps to keep the surfaces moist and defend against infection. Mucin reduces surface tension and forms a protective layer that prevents evaporation. This is very useful, for example, in maintaining proper eye lubrication.
Why do People Need Mucous Membrane Graft
A symblepharon is a condition where the insides of the eyelids stick abnormally to the eye’s surface (conjunctiva), caused by various issues like chemical injury or different diseases. If left untreated, this condition can limit eye movements and potentially even threaten sight. For mild cases, a type of tissue transplant using amniotic membrane (the lining that surrounds a fetus in the womb) can be useful. This treatment can help prevent the return of symblepharon by providing support to the growing cells.
A ‘contracted socket’ happens when the space left after the removal of an eye (due to a disease or accident) shrinks, making it harder for a prosthetic eye to fit and stay in place. This can happen as a result of many factors, such as excessive tissue loss during surgery or inflammation. To tackle this, a medical procedure that uses a graft of mucous membrane (a protective layer lining various body cavities) can be performed. This helps in expanding the socket, allowing a prosthetic eye to fit better. This method has been shown to be quite effective in patients with this condition.
‘Post-enucleation socket syndrome’ refers to complications that arise after the surgical removal of the eye. In this situation, the socket tends to appear sunken and angled backward. This condition can be corrected by fixing the socket with a specialized implant and supplementing it with a mucous membrane graft.
When an artificial eye’s supporting structure (orbital implant) becomes exposed, this can also be repaired using a graft from the buccal mucous membrane – the lining inside the mouth.
There are numerous conditions, like Steven Johnson syndrome or chemical burns, that can lead to abnormal eyelid shape, loss of eyelashes, and lid surface hardening. This can result in damage to the cornea (the clear front surface of the eye), potentially leading to blindness. To address this, the lid’s hardened margin can be treated with a mucous membrane graft, thereby aiming to prevent hardened tissue and eyelashes from touching the eye’s surface. In cases where a disease like ocular cicatricial pemphigoid is present, it’s crucial to control the underlying condition medically.
Chlamydia trachomatis infection causes trachoma, a major cause of blindness worldwide. This disease prompts an immune response that leads to severe scarring, primarily on the upper eyelid. The ensuing complications may cause corneal scarring and even blindness. Thus, surgery to correct the eyelid deformities can help prevent blindness.
Lastly, mucous membrane grafts can also be employed in the reconstruction of the eyelid after injury or in congenital conditions like cryptophthalmos (a rare disorder where the eyelids fail to separate in the early stages of fetal development).
For severe instances of symblepharon, where scar tissue must be removed, creating raw surfaces on the inside of the eyelid, the use of the amniotic membrane or mucous membrane grafts can provide relief and aid in healing.
When a Person Should Avoid Mucous Membrane Graft
Some people should not use this particular treatment if they have certain eye conditions, including:
– Severe kerato-conjunctivitis sicca, which is a fancy name for very dry eyes and inflammation.
– Advanced ocular cicatricial pemphigoid. This is a rare, serious condition that scars the inside of your eyelids and can hurt your vision.
– Active conjunctival inflammation, which is swelling and redness in the clear thin tissue that covers the front of the eye, that is not controlled by medications used to reduce the body’s immune response.
Equipment used for Mucous Membrane Graft
If your doctor is preparing a procedure on your eye, they need special tools to make sure everything goes well. For the initial phase, which doctors call “preparing the recipient bed”, the doctor uses things called “Westcott conjunctival scissors”—a kind of medical scissors made specially for eyes, as well as non-toothed forceps, which are like medical tweezers that won’t pinch or hurt the delicate tissue. They also use blotting paper, which is used to dry the area.
For the next step called “Fornix Formation”, the doctor will use a 4-0 silk, which is a type of thread that’s super thin and delicate, perfect for eyes. They will also use something called Castervejo forceps, which are similar to the previous forceps but are designed specifically for stitching up small, delicate places like the eyes.
Last for the “harvesting of the mucosal graft”, which is a fancy way of saying taking a small piece of healthy tissue from one place to put it in another (like a transplant) they again use the Westcott conjunctival scissors to do this safely and effectively.
Who is needed to perform Mucous Membrane Graft?
The inside skin layer of the lips is easily accessible and a special type of surgeon who focuses on eye-related surgeries can take tiny samples from this inside lip skin layer. However, if a patient needs a skin graft from the inside of their cheek, it might be a good idea to get help from a dentist who also performs surgeries.
Preparing for Mucous Membrane Graft
Before surgery, the patient is usually advised to use a mouthwash containing chlorhexidine or betadine for at least a week. These mouthwashes help clean the mouth and reduce the risk of infection.
How is Mucous Membrane Graft performed
Mucosal grafts are small pieces of tissue that can be taken from different parts of the body like the mouth, nose, vagina, or rectum and used elsewhere where it’s needed. The mouth is often the preferred area to take these grafts from because it’s easy to access and the procedure to remove the tissue is straightforward. In the mouth, grafts can be harvested from either the labial mucosa (the inside of the lip), the buccal mucosa (the inner cheek), or the hard palate (the roof of the mouth).
Getting a full-thickness mucous membrane graft, specifically from the buccal mucosa or inner cheek, is a common procedure because it reduces the possible ‘shrinkage’ of the graft after the surgery. This kind of grafting can be performed under local or general anesthesia. During the procedure, the doctor uses special tools to expose the mucosa and keeps it taut, aiding the removal of the graft.
The size of the graft needed is measured and marked on the donor site, the spot where the graft will come from. The site is then numbed and the incision site is marked before the incision is made and the graft is extracted. The removal of the graft needs to be done carefully to avoid damaging the underlying fat and glands, and to avoid injuring the buccinator muscle – a muscle responsible for facial expressions.
When the graft has been harvested, it is carefully separated from any attached fat using scissors, attached to the new site, and secured in place. Afterward, the original donor site is lightly cauterized – exposed to heat – to prevent excessive bleeding. In the days following the surgery, the patient is advised to use mouthwash and antibiotics and to opt for a liquid diet until the wound has healed.
Labial mucosal grafts from the lower lip are another option. This type of graft is achieved by understanding the anatomy of the lower lip and taking caution to avoid injuring nerves and muscles. Similarly, grafts can also be harvested from the minor salivary glands which are small glands scattered throughout the linings of the mouth and lips.
Lastly, there’s the possibility of getting only a part of the membrane, resulting in a split-thickness mucous membrane graft. This is less common, but may be preferred for visual reasons, as it might look better in the area where it’s placed.
Once the graft has been harvested, the donor site can either be sutured or left to heal naturally. The mouth has a remarkable ability to heal itself rapidly, due to the presence of growth factors in saliva and defensive cells protecting against infection. For aftercare, patients are advised to avoid eating hot and spicy foods and to use mouthwash and betadine gargles after meals for a week.
Possible Complications of Mucous Membrane Graft
If you’re having a surgical procedure involving grafts (pieces of tissue from your body that are moved to a different part of your body), there’s a chance you might run into complications. These issues might include the graft moving inappropriately, getting smaller than expected, dying off, becoming infected, forming unusual lumps of tissue, or leading to eyelid thickening over time. Some complications can also occur where the graft was taken from, such as infections, tissue death, wounds not healing properly, lip scarring, blood being trapped (a hematoma), ongoing pain, and numbness around the mouth if a nerve was accidentally damaged.
Some patients may experience a feeling of tightness in their mouth due to the wound shrinking, which could limit their ability to open their mouth fully. If this happens, additional surgeries might be needed to improve mouth opening ability. Some patients might notice changes in salivary function due to injury to the duct of a salivary gland. This could manifest as a decrease in saliva production caused by trauma or swelling after the surgery.
In rare cases, individuals might experience persistent numbness in the lower lip for several months after surgery. This usually disappears on its own, unless a nerve was injured during the procedure. There’s also a risk of lip tightening and lip inversion if the graft site in the lip isn’t carefully chosen.
Certain lifestyle factors, such as alcohol abuse and smoking, may pose a risk to the outcomes of the procedure, as they can lead to abnormal changes in the mouth’s lining. Some medications may also change the mouth’s lining and affect the outcome.
When grafts that involve the full thickness of the mucous membrane are used, they may remain pink, which might be a cosmetic concern if they’re visible. Meanwhile, grafts that involve only a portion of the mucous membrane are less pink, but they’re more likely to shrink. These two types of grafts are suited for different types of reconstructions.
In some instances, grafts may not work as expected and can eventually die off, which leads to a need for additional treatment approaches. Excessive secretion from salivary glands in the graft may also be a problem, requiring additional surgical interventions.
Finally, grafts taken from the inner cheek generally cause less post-surgery discomfort, fewer sensory deficits, and fewer changes to salivary flow when compared to grafts taken from the lower lip.
What Else Should I Know About Mucous Membrane Graft?
A grafting procedure using mucus membrane from the mouth is a straightforward treatment choice for the repair of eye surfaces. This can help patients with extreme scarring disorders like injuries from heat, Steven Johnson’s syndrome, and a condition known as ocular cicatricial pemphigoid. This technique can also be used to manage severely shrunken eye sockets.
One easily accessible source for grafting is the lining of the lips, known as the labial mucosa. This grafting process is pretty straightforward and an eye specialist, known as an ophthalmologist, can conveniently conduct it. Furthermore, the mouth offers a readily available and abundant source for grafts.
To add, the oral mucus membrane is thick and stable, which reduces the chances of repeated occurrences of the eye conditions.
