What is trigeminal trophic syndrome?
The trigeminal trophic syndrome is a rare form of cutaneous dysaesthesia that most often presents with ulceration of the ala nasi. This is the wing of tissue at the end of the nose above the nostril. The trigeminal trophic syndrome is due to damage to the trigeminal nerve.
What are the clinical features of trigeminal trophic syndrome?
The trigeminal trophic syndrome most often arises in women and the elderly. It results in sores affecting the skin supplied by the sensory component of the trigeminal nerve.
The first sign is a small crust that leads to a crescent-shaped ulcer on the side of the nose. The characteristic shape helps in distinguishing it from other possible causes. The ulcer may extend to the cheek and lips. Healing leads to fibrosis (scarring), and the lip may be drawn up into a characteristic sneer.
Similar lesions may also occur in the corners of the eyes, scalp or inside the mouth.
The tip of the nose is characteristically spared because it derives sensation from a different nerve, the medial branch of the anterior ethmoidal nerve.
How do the ulcers arise?
Any lesion in the central or peripheral nervous system which impairs the function of the trigeminal nerve can lead to the trigeminal trophic syndrome. The commonest causes are injuries or procedures such as trigeminal rhizotomy or injection of alcohol to the Gasserian ganglion. These are treatments for trigeminal neuralgia.
Signs of trigeminal trophic syndrome begin weeks to decades after the injury to the nerve – generally around a year later.
The damaged area feels numb (anaesthesia) or tingly/prickly (paraesthesia). This provokes rubbing, scratching, picking and eventually ulceration.
Some people with trigeminal trophic syndrome complain of a blocked nose or a foreign body in a nostril purely because of the loss of sensation which impairs the ability to perceive air flowing through the nostril.
Trigeminal trophic syndrome differs from dermatitis artefacta or compulsive skin picking as there is an identifiable neurological abnormality. The patient is aware of the problem and readily admits to manipulation of the area. Even so, it can be commoner in individuals with psychological disorders.
What is the differential diagnosis for trigeminal trophic syndrome?
Other causes of facial ulceration include infections, autoimmune disorders and malignancies (cancer).
Infections that need exclusion may include:
- Viruses: herpes zoster, herpes simplex
- Moulds and fungi: sporotrichosis, zygomycosis
- Bacteria: neuralgic leprosy, cutaneous tuberculosis, syphilis, yaws, anthrax
- Parasites: leishmaniasis
Autoimmune disorders causing facial ulceration include:
The most common skin cancers causing ulceration are:
What investigations are necessary for trigeminal trophic syndrome?
Laboratory tests are often necessary to differentiate the skin disorders listed above. There are no distinguishing blood tests or characteristic skin biopsy features in trigeminal trophic syndrome.
X-rays and other imaging studies may be performed to attempt to locate the site of trigeminal injury, but they may prove unhelpful.
What is the treatment for trigeminal trophic syndrome?
The treatment options for the trigeminal trophic syndrome are varied. Unfortunately, they are often ineffective.
Patient education about the cause of the ulceration is of paramount importance. Covering the area to prevent self-manipulation until the wound heals may be useful.
If chronic herpes simplex virus is responsible, symptoms may respond to antiviral therapy, such as longterm oral aciclovir.
Medications such as carbamazepine, amitriptyline, chlorpromazine have been used to reduce paraesthesia with questionable benefit.
Transcutaneous electrical stimulation, stellate ganglionectomy and ionising radiation (radiotherapy) have also been used as a treatment in resistant cases.
A rotation flap taking tissue from the innervated unaffected side to cover the ulcer has proved successful in a few cases.