Empty nose syndrome has been observed to affect a small proportion of people who have undergone surgery to the nose or sinuses, particularly those who have undergone turbinectomy (a procedure that removes some of the bones in the nasal passage). The incidence of ENS is variable and has not yet been quantified, but it is considered rare.

Untreated, the condition can cause significant and longterm physical and emotional distress in some people; some of the initial presentations on the condition described people who committed suicide. It is difficult to determine what treatments are safe and effective, and to what extent, in part because the diagnosis itself is unclear.

Initial treatment is similar to atrophic rhinitis, namely keeping the nasal mucosa moist with saline or oil-based lubricants and treating pain and infection as they arise; adding menthol to lubricants may be helpful in ENS, as may be use of a cool mist humidifer at home. For people with anxiety, depression, or who are obsessed with the feeling that they can't breathe, psychiatric or psychological care may be helpful.

In some people, surgery to restore missing or reduced turbinates may be beneficial.

A 2015 meta-analysis identified 128 people treated with surgery from eight studies that were useful to pool, with an age range of 18 to 64, most of whom had been suffering ENS symptoms for many years. The most common surgical approach was creating a pocket under the mucosa and implanting material - the amount and location were based on the judgement of the surgeon. In about half the cases a filler such as noncellular dermis, a medical-grade porous high-density polyethylene, or silastic was used and in about 40% cartilage taken from the person or from a cow was used. In a few cases hyaluronic acid was injected and in a few others tricalcium phosphate was used. There were no complications caused by the surgery, although one person was over-corrected and developed chronic rhinosinusitis and two people were under-corrected. The hyaluronic acid was completely resorbed in the three people who received it at the one year follow up, and in six people some of the implant came out, but this did not affect the result as enough remained. About 21% of the people had no or marginal improvement but the rest reported significant relief of their symptoms. Since none of the studies used placebo or blinding there may be a strong placebo effect or bias in reporting.

Causes can be remembered by mnemonic HERNIA:

- Hereditary factors: the disease runs in families

- Endocrine imbalance: the disease tends to start at puberty and mostly involves females

- Racial factors: whites are more susceptible than natives of equatorial Africa

- Nutritional deficiency: vitamins A or D, or iron

- Infection: "Klebsiella ozaenae", diphtheroids, "Proteus vulgaris", "E. coli", etc.

- Autoimmune factors: viral infection or some other unidentified insult may trigger antigenicity of the nasal mucosa.

Parry–Romberg syndrome appears to occur randomly and for unknown reasons. Prevalence is higher in females than males, with a ratio of roughly 3:2. The condition is observed on the left side of the face about as often as on the right side.

The fact that some people affected with this disease have circulating antinuclear antibodies in their serum supports the theory that Parry–Romberg syndrome may be an autoimmune disease, specifically a variant of localized scleroderma. Several instances have been reported where more than one member of a family has been affected, prompting speculation of an autosomal dominant inheritance pattern. However, there has also been at least one report of monozygotic twins in which only one of the twins was affected, casting doubt on this theory. Various other theories about the cause and pathogenesis have been suggested, including alterations in the peripheral sympathetic nervous system (perhaps as a result of trauma or infection involving the cervical plexus or the sympathetic trunk), as the literature reported it following sympathectomy, disorders in migration of cranial neural crest cells, or chronic cell-mediated inflammatory process of the blood vessels. It is likely that the disease results from different mechanisms in different people, with all of these factors potentially being involved.

Specific infections, such as syphilis, lupus, leprosy and rhinoscleroma, may cause destruction of the nasal structures leading to atrophic changes. Atrophic rhinitis can also result from long-standing purulent sinusitis or radiotherapy of the nose, or as a complication of surgery of the turbinates. The United Kingdom National Health Service has stated that "Most cases of atrophic rhinitis in the UK occur when the turbinates are damaged or removed during surgery". Some authors refer to as Atrophic rhinitis secondary to sinus surgery as the empty nose syndrome.

PND is suggested to be a cause of extra-oral halitosis, especially when a sinus infection is also present. Acid reflux or heartburn is believed to aggravate and in some cases cause post-nasal drip. Post-nasal drip can be a cause of laryngeal inflammation and hyperresponsiveness, leading to symptoms of vocal cord dysfunction (VCD).

Post-nasal drip (PND, also termed upper airway cough syndrome, UACS, or post nasal drip syndrome, PNDS) occurs when excessive mucus is produced by the nasal mucosa. The excess mucus accumulates in the throat or back of the nose. It is caused by rhinitis, sinusitis, gastroesophageal reflux disease (GERD), or by a disorder of swallowing (such as an esophageal motility disorder). It is frequently caused by an allergy, which may be seasonal or persistent throughout the year.

However, other researchers argue that mucus dripping down the back of the throat from the nasal cavity is a normal physiologic process that occurs in healthy individuals. Post-nasal drip has been challenged as a syndrome due to a lack of an accepted definition, pathologic tissue changes, and available biochemical tests.

Paraneoplastic acrokeratosis, Bazex syndrome (also known as acrokeratosis paraneoplastica of Bazex and acrokeratosis neoplastica) is a cutaneous condition characterized by psoriasiform changes of hands, feet, ears, and nose, with involvement of the nails and periungual tissues being characteristic and indistinguishable from psoriatic nails. The condition is associated with carcinomas of the upper aerodigestive tract.

This condition should not be confused with the other unrelated disease called Bazex syndrome, otherwise referred to as Bazex-Dupre-Christol syndrome.

Nablus mask-like facial syndrome is a microdeletion syndrome triggered by a deletion at chromosome 8 q22.1 that causes a mask-like facial appearance in those affected.

It is characterized by a narrowing of the eyes, tight, glistening facial skin, and a flat, broad nose. Other features of the syndrome include malformed ears, unusual hair patterns on the scalp, bent fingers and toes and joint deformities in the hands and feet, unusual teeth, mild developmental delay, cryptorchidism, and a generally happy disposition. It is a rare genetic disorder by inheritance found in Palestinian people named after Nablus city in the West Bank. It is part of many new genetic disorders of newborns that is increasing exponentially in Arabs in recent years as reported by Centre for Arab Genomic Studies in Dubai.

The cause of Goldenhar syndrome is largely unknown. However, it is thought to be multifactorial, although there may be a genetic component, which would account for certain familial patterns. It has been suggested that there is a branchial arch development issue late in the first trimester.

An increase in Goldenhar syndrome in the children of Gulf War veterans has been suggested, but the difference was shown to be statistically insignificant.

A temporary loss of smell can be caused by a blocked nose or infection. In contrast, a permanent loss of smell may be caused by death of olfactory receptor neurons in the nose or by brain injury in which there is damage to the olfactory nerve or damage to brain areas that process smell (see olfactory system). The lack of the sense of smell at birth, usually due to genetic factors, is referred to as "congenital anosmia." Family members of the patient suffering from congenital anosmia are often found with similar histories; this suggests that the anosmia may follow an autosomal dominant pattern. Anosmia may very occasionally be an early sign of a degenerative brain disease such as Parkinson's disease and Alzheimer's disease.

Another specific cause of permanent loss could be from damage to olfactory receptor neurons because of use of certain types of nasal spray; i.e., those that cause vasoconstriction of the nasal microcirculation. To avoid such damage and the subsequent risk of loss of smell, vasoconstricting nasal sprays should be used only when absolutely necessary and then for only a short amount of time. Non-vasoconstricting sprays, such as those used to treat allergy-related congestion, are safe to use for prescribed periods of time. Anosmia can also be caused by nasal polyps. These polyps are found in people with allergies, histories of sinusitis & family history. Individuals with cystic fibrosis often develop nasal polyps.

Amiodarone is a drug used in the treatment of arrhythmias of the heart. A clinical study performed demonstrated that the use of this drug induced anosmia in some patients. Although rare, there was a case in which a 66-year-old male was treated with Amiodarone for ventricular tachycardia. After the use of the drug he began experiencing olfactory disturbance, however after decreasing the dosage of Amiodarone, the severity of the anosmia decreased accordingly hence correlating the use of Amiodarone to the development of anosmia.

Prevalence ranges from 1 in 3500 to 5600 live births. Male-female ratio is found to be 3:2.

There is no known cure for this syndrome. Patients usually need ophthalmic surgery and may also need dental surgery

Genetic counseling and screening of the mother's relatives is recommended.

The recurrence of DOOR in siblings and the finding of DOOR syndrome in a few families with consanguinity suggest that the condition is an autosomal recessive genetic condition. Mutations in TBC1D24 have been identified in 9 families.

BPES is very rare: only 50-100 cases have been described. It affects slightly more males than females.

This syndrome is due to mutations in the Nance Horan gene (NHS) which is located on the short arm of the X chromosome (Xp22.13).

Anosmia can have a number of harmful effects. Patients with sudden onset anosmia may find food less appetizing, though congenital anosmics rarely complain about this, and none report a loss in weight. Loss of smell can also be dangerous because it hinders the detection of gas leaks, fire, and spoiled food. The common view of anosmia as trivial can make it more difficult for a patient to receive the same types of medical aid as someone who has lost other senses, such as hearing or sight.

Losing an established and sentimental smell memory (e.g. the smell of grass, of the grandparents' attic, of a particular book, of loved ones, or of oneself) has been known to cause feelings of depression.

Loss of olfaction may lead to the loss of libido, though this usually does not apply to congenital anosmics.

Often people who have congenital anosmia report that they pretended to be able to smell as children because they thought that smelling was something that older/mature people could do, or did not understand the concept of smelling but did not want to appear different from others. When children get older, they often realize and report to their parents that they do not actually possess a sense of smell, often to the surprise of their parents.

A study done on patients suffering from anosmia found that when testing both nostrils, there was no anosmia revealed; however, when testing each nostril individually, tests showed that the sense of smell was usually affected in only one of the nostrils as opposed to both. This demonstrated that unilateral anosmia is not uncommon in anosmia patients.

This disorder is present at birth, however, it may not be understood until several years after birth. Acrodysostosis affects males and females in almost similar numbers. It is difficult to determine the frequency of acrodysostosis in the population as many cases of this disorder cannot be diagnosed properly.

A unibrow is part of normal human variation, but can also stem from developmental disorders. A unibrow is a recognized feature of Cornelia De Lange syndrome, a genetic disorder whose main features include moderate to severe learning difficulties, limb abnormalities such as oligodactyly (fewer than normal fingers or toes) and phocomelia (malformed limbs), and facial abnormalities including a long philtrum (the slight depression/line between the nose and mouth).

Other medical conditions associated with a unibrow include:

- Waardenburg Syndrome;

- Patau Syndrome;

- Smith-Lemli-Opitz Syndrome;

- Sanfilippo Syndrome;

- 3p Deletion Syndrome;

- Chromosome Deletion Dillan 4p Syndrome (Wolf–Hirschhorn Syndrome);

- Gorlin Syndrome (Basal Cell Nevus Syndrome);

- Frontometaphyseal Dysplasia;

- ATRX Syndrome;

- Chromosome 9q34 Microdeletion Syndrome or Kleefstra syndrome.

Binder's Syndrome/Binder Syndrome (Maxillo-Nasal Dysplasia) is a developmental disorder primarily affecting the anterior part of the maxilla and nasal complex (nose and jaw). It is a rare disorder and the causes are unclear.

The characteristics of the syndrome are typically visible. The syndrome involves hypoplasia of variable severity of cartilaginous nasal septum and premaxilla. It includes complete total absence of the anterior nasal spine. There are also associated anomalies of muscle insertions of the upper lip and the nasal floor and of the cervical spine. Affected individuals typically have an unusually flat, underdeveloped midface (midfacial hypoplasia), with an abnormally short nose and flat nasal bridge. They have an underdeveloped upper jaw, relatively protruding lower jaw with anterior mandibular vertical excess and a Class III skeletal and dental (reverse overjet) profile. They have a small frontal sinus and global facial imbalance.

Treatment is encouraged as early as possible with posteroanterior traction on the maxilla and, at about age 8, reinsertion of the nasolabial muscles onto the anterior border of the cartilaginous system. Many who have a severe case of the disorder undergo plastic surgery or orthodontic treatment for cosmetic reasons.

Acrodysostosis also known as Arkless-Graham syndrome or Maroteaux-Malamut syndrome is a rare congenital malformation syndrome which involves shortening of the interphalangeal joints of the hands and feet, intellectual disability in approximately 90% of affected children, and peculiar facies. Other common abnormalities include short head (as measured front to back), small broad upturned nose with flat nasal bridge, protruding jaw, increased bone age, intrauterine growth retardation, juvenile arthritis and short stature. Further abnormalities of the skin, genitals, teeth, and skeleton may occur.

Most reported cases have been sporadic, but it has been suggested that the condition might be genetically related i.e. in an autosomal dominant mode of transmission. Both males and females are affected. The disorder has been associated with the older age of parents at the time of conception.

A PRKAR1A mutation has been identified in acrodysostosis with hormone resistance.

Many professionals that are likely to be involved in the treatment of those with Stickler's syndrome, include anesthesiologists, oral and maxillofacial surgeons; craniofacial surgeons; ear, nose, and throat specialists, ophthalmologists, optometrists, audiologists, speech pathologists, physical therapists and rheumatologists.

Overall, the estimated prevalence of Stickler syndrome is about 1 in 10,000 people. Stickler syndrome affects 1 in 7,500 to 9,000 newborns.

Blepharophimosis, ptosis, epicanthus inversus syndrome or BPES is a rare disease characterized by the conditions it is named after: blepharophimosis, ptosis, and epicanthus inversus.