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The long-term prognosis is uncertain, and has mostly to do with the underlying cause; i.e. autoimmune, paraneoplastic, etc. However, in recent years increased understanding of the basic mechanisms of NMT and autoimmunity has led to the development of novel treatment strategies. NMT disorders are now amenable to treatment and their prognoses are good. Many patients respond well to treatment, which usually provide significant relief of symptoms. Some cases of spontaneous remission have been noted, including Isaac's original two patients when followed up 14 years later.
While NMT symptoms may fluctuate, they generally don't deteriorate into anything more serious, and with the correct treatment the symptoms are manageable.
A very small proportion of cases with NMT may develop central nervous system findings in their clinical course, causing a disorder called Morvan's syndrome, and they may also have antibodies against potassium channels in their serum samples. Sleep disorder is only one of a variety of clinical conditions observed in Morvan's syndrome cases ranging from confusion and memory loss to hallucinations and delusions. However, this is a separate disorder.
Some studies have linked NMT with certain types of cancers, mostly lung and thymus, suggesting that NMT may be paraneoplastic in some cases. In these cases, the underlying cancer will determine prognosis. However, most examples of NMT are autoimmune and not associated with cancer.
The three causes of NMT are:
1. Acquired
2. Paraneoplastic
3. Hereditary
The acquired form is the most common, accounting for up to 80 percent of all cases and is suspected to be autoimmune-mediated, which is usually caused by antibodies against the neuromuscular junction.
The exact cause is unknown. However, autoreactive antibodies can be detected in a variety of peripheral (e.g. myasthenia gravis, Lambert-Eaton myasthenic syndrome) and central nervous system (e.g. paraneoplastic cerebellar degeneration, paraneoplastic limbic encephalitis) disorders. Their causative role has been established in some of these diseases but not all. Neuromyotonia is considered to be one of these with accumulating evidence for autoimmune origin over the last few years. Autoimmune neuromyotonia is typically caused by antibodies that bind to potassium channels on the motor nerve resulting in continuous/hyper-excitability. Onset is typically seen between the ages of 15–60, with most experiencing symptoms before the age of 40. Some neuromyotonia cases do not only improve after plasma exchange but they may also have antibodies in their serum samples against voltage-gated potassium channels. Moreover, these antibodies have been demonstrated to reduce potassium channel function in neuronal cell lines.
Antibodies against voltage-gated potassium channels (VGKC), which are detectable in about 40% of patients with acquired neuromytonia, have been implicated in Morvan’s pathophysiology. Raised serum levels of antibodies to VGKCs have been reported in three patients with Morvan’s Syndrome. Binding of serum from a patient with Morvan’s Syndrome to the hippocampus in a similar pattern of antibodies to known VGKC suggest that these antibodies can also cause CNS dysfunction. Additional antibodies against neuromuscular junction channels and receptors have also been described. Experimental evidence exists that these anti-VGKC antibodies cause nerve hyperexcitability by suppression of voltage gated K+ outward currents, whereas other, yet undefined humoral factors have been implicated in anti-VGKC antibody negative neuromyotonia. It is believed that antibodies to the Shaker-type K+ channels (the Kv1 family) are the type of potassium channel most strongly associated with acquired neuromyotonia and Morvan’s Syndrome.
Whether VGKC antibodies play a pathogenic role in the encephalopathy as they do in the peripheral nervous system is as yet unclear. It has been suggested that the VGKC antibodies may cross the blood–brain barrier and act centrally, binding predominantly to thalamic and striatal neurons causing encephalopathic and autonomic features.
Myasthenia gravis is the most common neuromuscular disease affecting function of the end plate in patients. It is present in 100 people out of 1,000,000 in the population, and its onset is usually in either younger or older individuals.(reference 14)
Acquired myasthenia gravis is the most common neuromuscular junction disease.(reference 7) Important observations were made by Patrick and Lindstrom in 1973 when they found that antibodies attacking the acetylcholine receptors were present in around 85% of cases of myasthenia gravis.(reference renamed form 13)(reference 36) The remaining diseases were also a result of antibody attacks on vital proteins, but instead of the acetylcholine receptor, the culprits were MuSK, a muscle-specific serum kinase, and lipoprotein receptor-related protein.(reference 36) So these mechanisms describe myasthenia gravis that is acquired, and not congenital, affecting these vital proteins by an immunological response against self-antigens. The cases not caused by antibodies against the acetylcholine receptors became by convention called seronegative myasthenia gravis.(reference 37) The term seronegative came about because scientists would be testing for acetylcholine receptor antibodies in patients that had myasthenia gravis resulting in negative tests in the serum. This does not imply that there are no antibodies present, but this terminology only became present because scientists were testing for the wrong antigen.(reference 36)(reference 38)
Neonatal myasthenia gravis is a very rare condition in which a mother with myasthenia gravis passes down her antibodies to her infant through the placenta, causing the it to be born with antibodies that will attach self-antigens.(reference 12)
Drug-induced myasthenia gravis is also a very rare condition in which pharmacological drugs cause a blockade or disruption of the NMJ machinery.(reference 12) Robert W. Barrons summarizes the possible causes of drug-induced myasthenia gravis: "Prednisone was most commonly implicated as aggravating myasthenia gravis, and D-penicillamine was most commonly associated with myasthenic syndrome. The greatest frequency of drug-induced neuromuscular blockade was seen with aminoglycoside-induced postoperative respiratory depression. However, drugs most likely to impact myasthenic patients negatively are those used in the treatment of the disease. These include overuse of anticholinesterase drugs, high-dose prednisone, and anesthesia and neuromuscular blockers for thymectomy."(reference 39)
It is not uncommon for drugs to damage muscle fibers. Particular families of drugs are known to induce myopathies on the molecular level, thus altering organelle function such as the mitochondria. Use of multiple drugs from these families in conjunction with one another can increase the risk of developing a myopathy. Many of the drugs associated with inducing myopathies in patients are found in rheumatology practice.
In one case, a patient was diagnosed with both Morvan's syndrome and pulmonary hyalinizing granulomas (PHG). PHG are rare fibrosing lesions of the lung, which have central whorled deposits of lamellar collagen. How these two diseases relate to one another is still unclear.
Thymoma, prostate adenoma, and in situ carcinoma of the sigmoid colon have also been found in patients with Morvan’s Syndrome.
Congenital syndromes affecting the neuromuscular junction are considered a very rare form of disease, occurring in 1 out of 200,000 in the United Kingdom.(reference 29) These are genetically inherited disorders. Symptoms are seen early since the affected individuals carry the mutation from birth. Congenital syndromes are usually classified by the location of the affected gene products. Congenital syndromes can have multiple targets affecting either the presynaptic, synaptic or postsynaptic parts of the neuromuscular junction.(reference 30) For example, if the malfunctioning or inactive protein is acetylcholinesterase, this would be classified as a synapse congenital syndrome.(reference 29)
Cramp fasciculation syndrome (CFS) is a rare peripheral nerve hyperexcitability disorder. It is more severe than the related (and common) disorder known as benign fasciculation syndrome; it causes fasciculations, cramps, pain, fatigue, and muscle stiffness similar to those seen in neuromyotonia (another related condition). Patients with CFS, like those with neuromyotonia, may also experience paresthesias.
Most cases of cramp fasciculation syndrome are idiopathic.
Cramp fasciculation syndrome is diagnosed by clinical examination and electromyography (EMG). Fasciculation is the only abnormality (if any) seen with EMG.
Cramp fasciculation syndrome is a chronic condition. Treatment options include anti-seizure medications such as carbamazepine, immunosuppressive drugs and plasmapheresis.
Treatment is similar to treatment for benign fasciculation syndrome.
Carbamazepine therapy has been found to provide moderate reductions in symptoms.
Many dietary factors and aberrations can induce ANIM. Chemical imbalances brought on by abnormal diets may either affect the muscle directly or induce abnormal functionality in upstream pathways.
- Excess Iodine consumption, especially in the form of kelp, can induce Hyperthyroidism. Hyperthyroidism is one of the most common ways to acquire ANIM. A hyperactive thyroid gland produces excessive amounts of hormones T3 and T4 leading to increased metabolism and increased sympathetic nervous system effects. The muscles exhibit a pathology similar to an overdose of epinephrine (commonly known as adrenaline). Patients with hyperthyroidism show weakness of shoulder girdle muscles in particular with this condition often being asymptomatic. More serious weakness of core and limb muscles may present.
- A dietary deficiency of vitamin D is most commonly associated with osteoporosis, but can cause ANIM as well. Vitamin D induced ANIM is most commonly associated with sleep deprivation as it induces tonsillar and adenotonsillar hypertrophy, as well as weakens the airway muscles. These changes induce sleep apnea and sleep disruption. Vitamin D induced ANM can also be associated with daytime impairment through this pathway.
Trauma to any muscle is also a common cause for acute ANIM. This is due to muscular contusions and partial or complete loss of function for affected muscle groups.
5 had positive response to immunotherapy and tumor therapy, 10 partial response, and 6 no response. Eventually 5 patients died; all had a tumor or additional paraneoplastic symptoms related to onconeuronal antibodies. Coexistence of onconeuronal antibodies predicted a poor outcome.
Prognosis is poor, however, current analysis suggests that those associated with thymoma, benign or malignant, show a less favorable prognosis (CASPR2 Ab positive).
Many doctors commonly recommend a combined treatment of: a warm compress applied to the eyes (to relieve muscle tension, relax the muscles, and reduce swelling); a small dosage of antihistamine (to reduce any swelling that may be caused by an allergic reaction); increase bed rest (to allow muscles to rest); decrease exposure to computer screens, televisions, or harsh lighting (to allow muscles to rest); and monitor caffeine intake (too much caffeine can cause an adverse reaction such as eye twitching, but a controlled dose can serve as an effective treatment by increasing blood flow).
Frequent contributing factors include: too much caffeine, high levels of anxiety, fatigue, dehydration, stress, overwork, and a lack of sleep. Use of certain drugs or alcohol may also be factors.
Magnesium deficiency.
Depending on subtype, many patients find that acetazolamide therapy is useful in preventing attacks. In some cases, persistent attacks result in tendon shortening, for which surgery is required.
Episodic ataxia (EA) is an autosomal dominant disorder characterized by sporadic bouts of ataxia (severe discoordination) with or without myokymia (continuous muscle movement). There are seven types recognised but the majority are due to two recognized entities. Ataxia can be provoked by stress, startle, or heavy exertion such as exercise. Symptoms can first appear in infancy. There are at least 6 loci for EA, of which 4 are known genes. Some patients with EA also have migraine or progressive cerebellar degenerative disorders, symptomatic of either familial hemiplegic migraine or spinocerebellar ataxia. Some patients respond to acetazolamide though others do not.
Other genetic causes of chorea are rare. They include the classical Huntington's disease 'mimic' or phenocopy syndromes, called Huntington's disease-like syndrome types 1, 2 and 3; inherited prion disease, the spinocerebellar ataxias type 1, 3 and 17, neuroacanthocytosis, dentatorubral-pallidoluysian atrophy (DRPLA), brain iron accumulation disorders, Wilson's disease, benign hereditary chorea, Friedreich's ataxia, mitochondrial disease and Rett syndrome.
The most common acquired causes of chorea are cerebrovascular disease and, in the developing world, HIV infection - usually through its association with cryptococcal disease.
Sydenham's chorea occurs as a complication of streptococcal infection. Twenty percent (20%) of children and adolescents with rheumatic fever develop Sydenham's chorea as a complication. It is increasingly rare, which may be partially due to penicillin, improved social conditions, and/or a natural reduction in the bacteria ( Streptococcus ) it has stemmed from. Psychological symptoms may precede or accompany this acquired chorea and may be relapsing and remitting. The broader spectrum of paediatric autoimmune neuropsychiatric disorders associated with streptococcal infection can cause chorea and are collectively referred to as PANDAS.
Chorea gravidarum refers to choreic symptoms that occur during pregnancy. If left untreated, the disease resolves in 30% of patients before delivery but, in the other 70%, it persists. The symptoms then progressively disappear in the next few days following the delivery.
Chorea may also be caused by drugs (commonly levodopa, anti-convulsants and anti-psychotics).
Other acquired causes include systemic lupus erythematosus, antiphospholipid syndrome, thyrotoxicosis, polycythaemia rubra vera, transmissible spongiform encephalopathies and coeliac disease.
Around 250 cases have been reported since the recognition of this syndrome. It is a rare syndrome with no known prevalence, although it is more common than the generalized form of acquired lipodystrophy (Lawrence syndrome).
- Race: No clear relationship exists between incidence and race in this syndrome; however, most reported patients have been of European descent.
- Age: The median age of onset of lipodystrophy has been reported to be around seven years; however, onset occurring as late as the fourth or fifth decade of life also has been reported. The median age at presentation has been about 25 years, and women have been found to present later than men (age 28 for women, age 18 for men).
- Sex: Analysis of the pooled data revealed female patients were affected about four times more often than males.
Estimating the mortality rate based on the available literature is difficult. Several case reports have revealed an association between acquired partial lipodystrophy and other diseases.
Nephropathy, in the form of membranoproliferative glomerulonephritis, occurs in about 20% of patients. Usually, patients do not have clinically evident renal disease or abnormalities in renal function until they have had the disease for 8 or more years. Membranoproliferative glomerulonephritis usually presents with asymptomatic proteinuria or hematuria.
The disease may gradually progress. About 40-50% of patients develop end-stage renal disease over the course of 10 years. This condition is responsible for most recurrent hospital admissions in patients with acquired partial lipodystrophy. Rapid progression of renal disease in a pregnant patient was reported. Recurrent disease in transplanted kidneys is common, although there have been reports of successful transplantations.
Associated autoimmune diseases (e.g., systemic lupus erythematosus, thyroiditis) contribute significantly to increased morbidity in these patients compared with the general population. Although uncommon, insulin resistance increases cardiovascular risk. Susceptibility to bacterial infections probably results from a C3 deficiency (due to complement activation and consumption of C3). Low C3 levels may impair complement-mediated phagocytosis and bacterial killing.
The prognosis for children with LKS varies. Some affected children may have a permanent severe language disorder, while others may regain much of their language abilities (although it may take months or years). In some cases, remission and relapse may occur. The prognosis is improved when the onset of the disorder is after age 6 and when speech therapy is started early. Seizures generally disappear by adulthood. Short-term remissions are not uncommon in LKS but they create difficulties in evaluating a patient's response to various therapeutic modalities.
The following table demonstrate the Long-Term Follow-up of Acquired Epileptic Aphasia across many different instrumental studies:.
Lower rates of good outcomes have been reported, ranging between 14% to 50%. Duran "et al." used 7 patients in his study (all males, aged 8–27 years of age) with LKS. On long-term followup, most of his patients did not demonstrate total epilepsy remission and language problems continued. Out of the seven patients, one reported a normal quality of life while the other six reported aphasia to be a substantial struggle. The Duran "et al." study is one of few that features long-term follow up reports of LKS and utilizes EEG testing, MRIs, the Vineland Adaptive Behavior Scales, the Connor's Rating Scales-revised, and a Short-Form Health Survey to analyze its patients.
Globally, more than 200 cases of acquired epileptic aphasia have been described in the literature. Between 1957 and 1980, 81 cases of acquired epileptic aphasia were reported, with 100 cases generally being diagnosed every 10 years.
The mechanism for paraneoplastic syndrome varies from case to case. However, pathophysiological outcomes usually arise from when a tumor arises. Paraneoplastic syndrome often occurs alongside associated cancers as a result of activated immune systems. In this scenario, the body may produce antibodies to fight off the tumor by directly binding and destroying the tumor cell. Paraneoplastic disorders may arise in that antibodies would cross-react with normal tissues and destroy them.
Treatment options include:
1. Therapies to eliminate the underlying cancer, such as chemotherapy, radiation and surgery.
2. Therapies to reduce or slow neurological degeneration. In this scenario, rapid diagnosis and treatment are critical for the patient to have the best chance of recovery. Since these disorders are relatively rare, few doctors have seen or treated paraneoplastic neurological disorders (PNDs). Therefore, PND patients should consult with a specialist with experience in diagnosing and treating paraneoplastic neurological disorders.
A specific prognosis for those afflicted with paraneoplastic syndromes links to each unique case presented. Thus, prognosis for paraneoplastic syndromes may vary greatly. For example, paraneoplastic pemphigus often included infection as a major cause of death. Paraneoplastic pemphigus is one of the three major subtypes that affects IgG autoantibodies that are characteristically raised against desmoglein 1 and desmoglein 3 (which are cell-cell adhesion molecules found in desmosomes). Underlying cancer or irreversible system impairment, seen in acute heart failure or kidney failure, may result in death as well.
Acquired C1 esterase inhibitor deficiency also known as "Acquired Angioedema" presents with symptoms indistinguishable from hereditary angioedema, but generally with onset after the fourth decade of life.
C4 levels are low and C3 levels are normal.
Treatment for LKS usually consists of medications, such as anticonvulsants and corticosteroids (such as prednisone), and speech therapy, which should be started early. Some patients improve with the use of corticosteroids or adrenocorticotropin hormone (ACTH) which lead researches to believe that inflammation and vasospasm may play a role in some cases of acquired epileptic aphasia.
A controversial treatment option involves a surgical technique called multiple subpial transection in which multiple incisions are made through the cortex of the affected part of the brain beneath the pia mater, severing the axonal tracts in the subjacent white matter. The cortex is sliced in parallel lines to the midtemporal gyrus and perisylvian area to attenuate the spread of the epileptiform activity without causing cortical dysfunction. There is a study by Morrell "et al." in which results were reported for 14 patients with acquired epileptic aphasia who underwent multiple subpial transections. Seven of the fourteen patients recovered age-appropriate speech and no longer required speech therapy. Another 4 of the 14 displayed improvement of speech and understanding instructions given verbally, but they still required speech therapy. Eleven patients had language dysfunction for two or more years. Another study by Sawhney "et al." reported improvement in all three of their patients with acquired epileptic aphasia who underwent the same procedure.
Various hospitals contain programs designed to treat conditions such as LKS like the Children's Hospital Boston and its Augmentative Communication Program. It is known internationally for its work with children or adults who are non-speaking or severely impaired. Typically, a care team for children with LKS consists of a neurologist, a neuropsychologist, and a speech pathologist or audiologist. Some children with behavioral problems may also need to see a child psychologist and a psychopharmacologist. Speech therapy begins immediately at the time of diagnosis along with medical treatment that may include steroids and anti-epileptic or anti-convulsant medications.
Patient education has also proved to be helpful in treating LKS. Teaching them sign language is a helpful means of communication and if the child was able to read and write before the onset of LKS, that is extremely helpful too.