The onset is usually as early as birth and initial symptoms include swallowing difficulties, self-mutilation, and delayed development . Later on, the perception of pain and temperature may be either partially or completely absent, followed by depressed reflexes and autonomic dysfunction presenting with postural hypotension, excessive sweating and gastroesophageal reflux . Frequent fractures, skin and corneal ulceration, intermittent fevers, irritability and behavioral issues (type IV), scoliosis and osteomyelitis after injury are also observed in a significant number of individuals  , whereas life-threatening recurrent aspirations are characteristic for type III .
A detailed patient history that reveals similar symptoms within the family or first-degree relatives may be one of the most important parts in the workup, together with a thorough physical examination that can confirm sensory and/or autonomic dysfunction . The initial diagnosis should be made on clinical grounds, as genetic tests are available for only a few subtypes  . Intradermal injection of histamine phosphate is a useful diagnostic method and in HSN patients . Normally, a diffuse reaction around a central histamine-induced wheal should be observed, but if HSN is present, a reduced axonal flare manifesting as a narrow areola around the wheal will be seen in virtually all types .
Supportive care is the mainstay of therapy, as there is no cure for HSN, regardless of the type. Topical lubricants are used to prevent corneal scarring, GABA agonists, anticholinergics and alpha-adrenergic agonists are used to cope with varying degrees of gastrointestinal dysfunction, hydration and exercise are recommended for long-term preservation of the cardiovascular system and various orthopedic measures in the form of splints and braces are used to reduce the burden of fractures  .
At this moment, seven types of HSN are recognized  :
Congenital autonomic dysfunction with universal pain loss (CAD) and progressive panneuropathy have also been proposed as subtypes of HSN .
Type III is estimated to occur in 1 per 3,600 live births and is exclusively seen in the Eastern European Jewish population, whereas types II and III are very rarely encountered in clinical practice . Family history is considered as the most important risk factor for virtually all types.
Across all types, genetic mutations have shown to impair lipid metabolism, regulation of intracellular vesicular transport, the activity of nerve growth factors and regulators of transcription, eventually leading to neuronal atrophy and degeneration of sensory and autonomic fibers  .
Genetic counseling can be recommended to parents with known family members suffering from HSN.
Hereditary sensory neuropathy (HSN) is a term encompassing several disorders inherited through either autosomal dominant or recessive patterns . At this moment, seven types have been recognized and classified as HSN subtypes, all distinguished with some form of sensory (disrupted sensation of pain and temperature, hyporeflexia) and/or autonomic (postural hypotension, excessive sweating, gastroesophageal reflux) dysfunction , which is why the term hereditary sensory and autonomic neuropathy (HSAN) is often used . Chronic skin ulcers, spontaneous fractures, and neuropathic arthropathy necessitating amputations are constitutive parts of the clinical presentation as well . The diagnosis is primarily made by obtaining a thorough patient history and a detailed physical examination, but a unique feature of almost all types is an abnormally reduced axonal flare after intradermal injection of histamine phosphate . Genetic tests are not readily available and treatment is mainly supportive.
Hereditary sensory neuropathy (HSN) is a disorder characterized by degeneration of neurons that regulate sensory input, such as temperature and pain, and autonomic functions, including blood pressure regulation and activity of the gastrointestinal system. So far, seven types have been described in the literature, with five caused by genetic mutations that are inherited by children from their parents. The clinical presentation starts from birth, with main signs being swallowing difficulties, a reduced sense of pain and temperature perception leading to severe unintentional injuries and fractures, blood pressure changes, skin and corneal ulcerations, but also behavioral changes in the form of irritability and rage. The diagnosis is primarily made based on clinical signs and symptoms, whereas treatment mainly consists of supportive care, as there is no cure for any of the recognized subtypes. Genetic counseling is recommended for parents with a positive family history for HSN, as the condition profoundly impacts the quality of life of patients and their families.