Those at the overall highest risk for lateral medullary syndrome are men at an average age of 55.06. Having a history of hypertension, diabetes and smoking all increase the risk of large artery atherosclerosis. Large artery atherosclerosis is thought to be the greatest risk factor for lateral medullary syndrome due to the deposits of cholesterol, fatty substances, cellular waste products, calcium and fibrin. Otherwise known as plaque build up in the arteries.

It can be caused by an interruption to the blood supply of the anterior inferior cerebellar artery or circumferential arteries.

A lateral pontine syndrome is a lesion which is similar to the lateral medullary syndrome, but because it occurs in the pons, it also involves the cranial nerve nuclei of the pons.

Medial medullary syndrome, also known as inferior alternating syndrome, hypoglossal alternating hemiplegia, lower alternating hemiplegia, or Dejerine syndrome, is a type of alternating hemiplegia characterized by a set of clinical features resulting from occlusion of the anterior spinal artery. This results in the infarction of medial part of the medulla oblongata.

Medial pontine syndrome results from occlusion of paramedian branches of the basilar artery.

The infarction (which arises in the paramedian branches of the anterior spinal artery and/or the vertebral arteries) leads to death of the ipsilateral medullary pyramid, the medial leminiscus, and the hypoglossal nerve fibers that pass through the medulla. The spinothalamic tract is spared because it is located more laterally in the brainstem and is not supplied by the anterior spinal artery, but rather by the vertebral and posterior inferior cerebellar arteries. The trigeminal nucleus is also spared, since most of it is higher up in the pons, and the spinal part of it found in the medulla is lateral to the infarct.

Although medial pontine syndrome has many similarities to medial medullary syndrome, because it is located higher up the brainstem in the pons, it affects a different set of cranial nuclei.

Depending upon the size of the infarct, it can also involve the facial nerve.

The outlook for someone with lateral medullary syndrome depends upon the size and location of the area of the brain stem damaged by the stroke. Some individuals may see a decrease in their symptoms within weeks or months. Others may be left with significant neurological disabilities for years after the initial symptoms appeared. However, more than 85% of patients have seen minimal symptoms present at six months from the time of the originatl stroke, and have been able to independently accomplish average daily within a year.

Foville's syndrome is caused by the blockage of the perforating branches of the basilar artery in the region of the brainstem known as the pons. Most frequently caused by vascular disease or tumors involving the dorsal pons.[3]

Structures affected by the infarct are the PPRF, nuclei of cranial nerves VI and VII, corticospinal tract, medial lemniscus, and the medial longitudinal fasciculus. There's involvement of the fifth to eighth cranial nerves, central sympathetic fibres (Horner syndrome) and horizontal gaze palsy.[3]

Pheochromocytoma is seen in between two and eight in 1,000,000, with approximately 1000 cases diagnosed in United States yearly. It mostly occurs in young or middle age adults, though it presents earlier in hereditary cases.

- About 10% of adrenal cases are bilateral (suggesting hereditary disease)

- About 10% of adrenal cases occur in children (also suggesting hereditary disease)

- About 15% are extra-adrenal (located in any orthosympathetic tissue): Of these 9% are in the abdomen, and 1% are located elsewhere. Some extra-adrenal pheochromocytomas are probably actually paragangliomas, but the distinction can only be drawn after surgical resection.

- About 11.1% of adrenal cases are malignant, but this rises to 30% for extra-adrenal cases

- About 15–20% are hereditary

- About 5% are caused by VHL disease

- About 3% recur after being resected

- About 14% of affected individuals do not have arterial hypertension (Campbell's Urology)

In terms of treatment/management one should observe what signs or symptoms are present and therefore treat those as there is no other current guideline. The affected individual should be monitored for cancer of:

- Thyroid

- Breast

- Renal

The massive release of catecholamines in pheochromocytoma can cause damage to heart cells. This damage may be due to either compromising the coronary microcirculation or by direct toxic effects on the heart cells.

Multiple Endocrine Neoplasia type 1 (MEN1) is a rare hereditary endocrine cancer syndrome characterized primarily by tumors of the parathyroid glands (95% of cases), endocrine gastroenteropancreatic (GEP) tract (30-80% of cases), and anterior pituitary (15-90% of cases). Other endocrine and non-endocrine neoplasms including adrenocortical and thyroid tumors, visceral and cutaneous lipomas, meningiomas, facial angiofibromas and collagenomas, and thymic, gastric, and bronchial carcinoids also occur. The phenotype of MEN1 is broad, and over 20 different combinations of endocrine and non-endocrine manifestations have been described. MEN1 should be suspected in patients with an endocrinopathy of two of the three characteristic affected organs, or with an endocrinopathy of one of these organs plus a first-degree relative affected by MEN1 syndrome.

MEN1 patients usually have a family history of MEN1. Inheritance is autosomal dominant; any affected parent has a 50% chance to transmit the disease to his or her progeny. MEN1 gene mutations can be identified in 70-95% of MEN1 patients.

Many endocrine tumors in MEN1 are benign and cause symptoms by overproduction of hormones or local mass effects, while other MEN1 tumors are associated with an elevated risk for malignancy. About one third of patients affected with MEN1 will die early from an MEN1-related cancer or associated malignancy. Entero-pancreatic gastrinomas and thymic and bronchial carcinoids are the leading cause of morbidity and mortality. Consequently, the average age of death in untreated individuals with MEN1 is significantly lower (55.4 years for men and 46.8 years for women) than that of the general population.

A recommend surveillance program for Multiple Endocrine Neoplasia Type 1 has been suggested by the International Guidelines for Diagnosis and Therapy of MEN syndromes group.

This produces ipsilateral horizontal gaze palsy and facial nerve palsy and contralateral hemiparesis, hemisensory loss, and internuclear ophthalmoplegia.

The genetics of the Bannayan–Riley–Ruvalcaba syndrome is determined, in the majority of cases, via the PTEN gene which presents about 30 mutations in this condition. This gene which regulates cell growth, when "not" working properly can lead to hamartomas. PTEN chromosomal location is 10q23.31, while the molecular location is 87,863,438 to 87,971,930 There are many syndromes that are linked to PTEN aside from Bannayan–Riley–Ruvalcaba Syndrome.

The syndrome combines Bannayan–Zonana syndrome, Riley–Smith syndrome, and Ruvalcaba–Myhre–Smith syndrome. Bannayan–Zonana syndrome is named for George A. Bannayan and Jonathan Zonana

When inherited, multiple endocrine neoplasia type 2 is transmitted in an autosomal dominant pattern, which means affected people have one affected parent, and possibly affected siblings and children. Some cases, however, result from spontaneous new mutations in the "RET gene". These cases occur in people with no family history of the disorder. In MEN2B, for example, about half of all cases arise as spontaneous new mutations.

The table in the multiple endocrine neoplasia article lists the genes involved in the various MEN syndromes. Most cases of MEN2 derive from a variation in the "RET proto-oncogene", and are specific for cells of neural crest origin. A database of MEN" implicated RET mutations is maintained by the University of Utah Department of Physiology.

The protein produced by the "RET gene" plays an important role in the TGF-beta (transforming growth factor beta) signaling system. Because the TGF-beta system operates in nervous tissues throughout the body, variations in the RET gene can have effects in nervous tissues throughout the body.

MEN2 generally results from a gain-of-function variant of a "RET gene". Other diseases, such as Hirschsprung disease, result from loss-of-function variants. OMIM # lists the syndromes associated with the RET gene.

Without treatment, persons with MEN2B die prematurely. Details are lacking, owing to the absence of formal studies, but it is generally assumed that death in the 30s is typical unless prophylactic thyroidectomy and surveillance for pheochromocytoma are performed (see below). The range is quite variable, however: death early in childhood can occur, and it is noteworthy that a few untreated persons have been diagnosed in their 50s. Recently, a larger experience with the disease "suggests that the prognosis in an individual patient may be better than previously considered."

Thyroidectomy is the mainstay of treatment, and should be performed without delay as soon as a diagnosis of MEN2B is made, even if no malignancy is detectable in the thyroid. Without thyroidectomy, almost all patients with MEN2B develop medullary thyroid cancer, in a more aggressive form than MEN 2A. The ideal age for surgery is 4 years old or younger, since cancer may metastasize before age 10.

Pheochromocytoma - a hormone secreting tumor of the adrenal glands - is also present in 50% of cases. Affected individuals are encouraged to get yearly screenings for thyroid and adrenal cancer.

Because prophylactic thyroidectomy improves survival, blood relatives of a person with MEN2B should be evaluated for MEN2B, even if lacking the typical signs and symptoms of the disorder.The mucosal neuromas of this syndrome are asymptomatic and self-limiting, and present no problem requiring treatment. They may, however, be surgically removed for aesthetic purposes or if they are being constantly traumatized.

Dissociated sensory loss is a pattern of neurological damage caused by a lesion to a single tract in the spinal cord which involves "selective" loss of fine touch and proprioception "without" loss of pain and temperature, or vice versa.

Understanding the mechanisms behind these selective lesions requires a brief discussion of the anatomy involved.

Loss of pain and temperature are due to damage to the lateral spinothalamic tracts, which cross the central part of the cord close to the level where they enter it and travel up the spinal column on the opposite side to the one they innervate (i.e. they "ascend contralaterally"). Note that a lesion of the lateral spinothalamic tract at a given level will not result in sensory loss for the dermatome of the same level; this is due to the fibers of the tract of Lissauer which transmit the neuron one or two levels above the affected segment (thus bypassing the segmental lesion on the contralateral side).

Loss of fine touch and proprioception are due to damage to the dorsal columns, which do not cross the cord until the brainstem, and so travel up the column on the same side to the one they innervate (i.e. they "ascend ipsilaterally").

This means that a lesion of the dorsal columns will cause loss of touch and proprioception below the lesion and on the same side as it, while a lesion of the spinothalamic tracts will cause loss of pain and temperature below the lesion and on the opposite side to it.

Dissociated sensory loss always suggests a focal lesion within the spinal cord or brainstem.

The location of cord lesions affects presentation—for instance, a central lesion (such as that of syringomyelia) will knock out second order neurons of the spinothalamic tract as they cross the centre of the cord, and will cause loss of pain and temperature without loss of fine touch or proprioception.

Other causes of dissociated sensory loss include:

- Diabetes mellitus

- Syringomyelia

- Brown-Séquard syndrome

- Lateral medullary syndrome aka Wallenberg's syndrome

- Anterior spinal artery thrombosis

- Tangier disease

- Subacute combined degeneration

- Multiple sclerosis

- Tabes dorsalis

- Friedreich's ataxia (or other spinocerebellar degeneration)

Anterior cerebral artery syndrome is a condition whereby the blood supply from the anterior cerebral artery (ACA) is restricted, leading to a reduction of the function of the portions of the brain supplied by that vessel: the medial aspects of the frontal and parietal lobes, basal ganglia, anterior fornix and anterior corpus callosum.

Depending upon the area and severity of the occlusion, signs and symptoms may vary within the population affected with ACA syndrome. Blockages to the proximal (A1) segment of the vessel produce only minor deficits due to the collateral blood flow from the opposite hemisphere via the anterior communicating artery. Occlusions distal to this segment will result in more severe presentation of ACA syndrome. Contralateral hemiparesis and hemisensory loss of the lower extremity is the most common symptom associated with ACA syndrome.

Variations in the RET proto-oncogene cause MEN2B. In recent decades no case of MEN2B has been reported that lacks such a variation. The M918T variant alone is responsible for approximately 95% of cases. All DNA variants that cause MEN2B are thought to enhance signaling through the RET protein, which is a receptor molecule found on cell membranes, whose ligands are part of the transforming growth factor beta signaling system.

About half of cases are inherited from a parent as an autosomal dominant trait. The other half appear to be spontaneous mutations, usually arising in the paternal allele, particularly from older fathers. The sex ratio in de novo cases is also uneven: sons are twice as likely to develop MEN 2B as daughters.

In medicine, split hand syndrome is a neurological syndrome in which the hand muscles on the side of the thumb (lateral, thenar eminence) appear wasted, whereas the muscles on the side of the little finger (medial, hypothenar eminence) are spared. Anatomically, the abductor pollicis brevis and first dorsal interosseous muscle are more wasted than the abductor digiti minimi.

If lesions affecting the branches of the ulnar nerve that run to the wasted muscles are excluded, the lesion is almost sure to be located in the anterior horn of the spinal cord at the C8-T1 level. It has been proposed as a relatively specific sign for amyotrophic lateral sclerosis (ALS or Lou Gehrig's disease). It can also occur in other disorders affecting the anterior horn, such as spinal muscular atrophy, Charcot-Marie-Tooth disease, poliomyelitis and progressive muscular atrophy. A slow onset and a lack of pain or sensorial symptoms are arguments against a lesion of the spinal root or plexus brachialis. To an extent, these features can also be seen in normal aging (although technically, the apparent muscle wasting is sarcopenia rather than atrophy).

The term split hand syndrome was first coined in 1994 by a researcher from the Cleveland Clinic called Asa J. Wilbourn.

The cause of alternating hemiplegia is the mutation of ATP1A3 gene. In a study of fifteen females and nine males’ patient with alternating hemiplegia, a mutation in ATP1A3 gene was present. Three patients showed heterozygous de-novo missense mutation. Six patients were found with de-novo missense mutation and one patient was identified with de-novo splice site mutation. De novo mutation is a mutation that occurs in the germ cell of one parent. Neither parent has the mutation, but it is passed to the child through the sperm or egg.

Singleton Merten Syndrome is an autosomal dominate genetic disorder with variable expression with an onset of symptoms during childhood.