Directly assessing nerve conduction of electrical impulses can exclude other causes of acute muscle weakness, as well as distinguish the different types of Guillain–Barré syndrome. Needle electromyography (EMG) and nerve conduction studies may be performed. In the first two weeks, these investigations may not show any abnormality. Neurophysiology studies are not required for the diagnosis.

Formal criteria exist for each of the main subtypes of Guillain–Barré syndrome (AIDP and AMAN/AMSAN, see below), but these may misclassify some cases (particularly where there is reversible conduction failure) and therefore changes to these criteria have been proposed. Sometimes, repeated testing may be helpful.

Cerebrospinal fluid envelops the brain and the spine, and lumbar puncture or spinal tap is the removal of a small amount of fluid using a needle inserted between the lumbar vertebrae. Characteristic findings in Guillain–Barré syndrome are an elevated protein level, usually greater than 0.55 g/L, and fewer than 10 white blood cells per cubic millimeter of fluid ("albuminocytological dissociation"). This combination distinguishes Guillain–Barré syndrome from other conditions (such as lymphoma and poliomyelitis) in which both the protein and the cell count are elevated. Elevated CSF protein levels are found in approximately 50% of patients in the first 3 days after onset of weakness, which increases to 80% after the first week.

Repeating the lumbar puncture during the disease course is not recommended. The protein levels may rise after treatment has been administered.

Most patients reported in the literature have been given treatments suitable for autoimmune neurological diseases, such as corticosteroids, plasmapheresis and/or intravenous immunoglobulin, and most have made a good recovery. The condition is too rare for controlled trials to have been undertaken.

Anti-GQ1b antibodies are found in two-thirds of patients with this condition. This antibody is also found in almost all cases of Miller Fisher syndrome. The EEG is often abnormal, but shows only slow wave activity, which also occurs in many other conditions, and so is of limited value in diagnosis. Similarly, raised CSF protein levels and pleocytosis are frequent but non-specific. It was originally thought that raised CSF protein without pleocytosis ('albuminocytological dissociation') was a characteristic feature, as it is in Guillain–Barré syndrome, but this has not been supported in more recent work. In only 30% of cases is a MRI brain scan abnormal. Nerve conduction studies may show an axonal polyneuropathy.

The important factors for successful prevention of GBS-EOD using IAP and the universal screening approach are:

- Reach most pregnant women for antenatal screens

- Proper sample collection

- Using an appropriate procedure for detecting GBS

- Administering a correct IAP to GBS carriers

Most cases of GBS-EOD occur in term infants born to mothers who screened negative for GBS colonization and in preterm infants born to mothers who were not screened, though some false-negative results observed in the GBS screening tests can be due to the test limitations and to the acquisition of GBS between the time of screening and delivery. These data show that improvements in specimen collection and processing methods for detecting GBS are still necessary in some settings. False-negative screening test, along with failure to receive IAP in women delivering preterm with unknown GBS colonization status, and the administration of inappropriate IAP agents to penicillin-allergic women account for most missed opportunities for prevention of cases of GBS-EOD.

GBS-EOD infections presented in infants whose mothers had been screened as GBS culture-negative are particularly worrying, and may be caused by incorrect sample collection, delay in processing the samples, incorrect laboratory techniques, recent antibiotic use, or GBS colonization after the screening was carried out.

No current culture-based test is both accurate enough and fast enough to be recommended for detecting GBS once labour starts. Plating of swab samples requires time for the bacteria to grow, meaning that this is unsuitable as an intrapartum point-of-care test.

Alternative methods to detect GBS in clinical samples (as vaginorectal swabs) rapidly have been developed, such are the methods based on nucleic acid amplification tests, such as polymerase chain reaction (PCR) tests, and DNA hybridization probes. These tests can also be used to detect GBS directly from broth media, after the enrichment step, avoiding the subculture of the incubated enrichment broth to an appropriate agar plate.

Testing women for GBS colonization using vaginal or rectal swabs at 35–37 weeks of gestation and culturing them in enriched media is not as rapid as a PCR test that would check whether the pregnant woman is carrying GBS at delivery. And PCR tests, allow starting IAP on admission to the labour ward in those women in whom it is not known if they are GBS carriers or not. PCR testing for GBS carriage could, in the future, be sufficiently accurate to guide IAP. However, the PCR technology to detect GBS must be improved and simplified to make the method cost-effective and fully useful as point-of-care testing]] to be carried out in the labour ward (bedside testing). These tests still cannot replace antenatal culture for the accurate detection of GBS carriers.

Neonatal sepsis of the newborn is an infection that has spread through the entire body. The inflammatory response to this systematic infection can be as serious as the infection itself. In infants that weigh under 1500 g, sepsis is the most common cause of death. Three to four percent of infants per 1000 births contract sepsis. The mortality rate from sepsis is near 25%. Infected sepsis in an infant can be identified by culturing the blood and spinal fluid and if suspected, intravenous antibiotics are usually started. Lumbar puncture is controversial because in some cases it has found not to be necessary while concurrently, without it estimates of missing up to one third of infants with meningitis is predicted.

Patients presenting with this disease undergo antibiotic treatment and gammaglobulin transfusions. Antibiotics are used to fight off the pathogenic organisms and the gammaglobulin helps provide a normal balance of antibodies to fight the infection. Bone marrow transplantation may be an option in some cases.

OMIM: 308230

Symptoms and the isolation of the virus pathogen the upper respiratory tract is diagnostic. Virus identification is specific immunologic methods and PCR. The presence of the virus can be rapidly confirmed by the detection of the virus antigen. The methods and materials used for identifying the RSV virus has a specificity and sensitivity approaching 85% to 95%. Not all studies confirm this sensitivity. Antigen detection has comparatively lower sensitivity rates that approach 65% to 75%.

Babies born from mothers with symptoms of Herpes Simplex Virus (HSV) should be tested for viral infection. Liver tests, complete blood count (CBC), cerebrospinal fluid analyses, and chest X-ray should all be completed to diagnose meningitis. Samples should be taken from skin, conjunctiva (eye), mouth and throat, rectum, urine, and the CSF for viral culture and PCR analysis with respect to the sample from CSF.

A lumbar puncture (LP) is necessary to diagnose meningitis. Cerebrospinal fluid (CSF) culture is the most important study for the diagnosis of neonatal bacterial meningitis because clinical signs are non-specific and unreliable. Blood cultures may be negative in 15-55% of cases, deeming it unreliable as well. However, a CSF/blood glucose ratio below two-thirds has a strong relationship to bacterial meningitis. A LP should be done in all neonates with suspected meningitis, with suspected or proven sepsis (whole body inflammation) and should be considered in all neonates in whom sepsis is a possibility. The role of the LP in neonates who are healthy appearing but have maternal risk factors for sepsis is more controversial; the yield of the LP in these patients may be low.

Early-onset is deemed when infection is within one week of birth. Late-onset is deemed after the first week.

The CDC recommends screening some pregnant women even if they do not have symptoms of infection. Pregnant women who have traveled to affected areas should be tested between two and twelve weeks after their return from travel. Due to the difficulties with ordering and interpreting tests for Zika virus, the CDC also recommends that healthcare providers contact their local health department for assistance. For women living in affected areas, the CDC has recommended testing at the first prenatal visit with a doctor as well as in the mid-second trimester, though this may be adjusted based on local resources and the local burden of Zika virus. Additional testing should be done if there are any signs of Zika virus disease. Women with positive test results for Zika virus infection should have their fetus monitored by ultrasound every three to four weeks to monitor fetal anatomy and growth.

For infants with suspected congenital Zika virus disease, the CDC recommends testing with both serologic and molecular assays such as RT-PCR, IgM ELISA and plaque reduction neutralization test (PRNT). RT-PCR of the infants serum and urine should be performed in the first two days of life. Newborns with a mother who was potentially exposed and who have positive blood tests, microcephaly or intracranial calcifications should have further testing including a thorough physical investigation for neurologic abnormalities, dysmorphic features, splenomegaly, hepatomegaly, and rash or other skin lesions. Other recommended tests are cranial ultrasound, hearing evaluation, and eye examination. Testing should be done for any abnormalities encountered as well as for other congenital infections such as syphilis, toxoplasmosis, rubella, cytomegalovirus infection, lymphocytic choriomeningitis virus infection, and herpes simplex virus. Some tests should be repeated up to 6 months later as there can be delayed effects, particularly with hearing.

Gleich's syndrome or episodic angioedema with eosinophilia is a rare disease in which the body swells up episodically (angioedema), associated with raised antibodies of the IgM type and increased numbers of eosinophil granulocytes, a type of white blood cells, in the blood (eosinophilia). It was first described in 1984.

Its cause is unknown, but it is unrelated to capillary leak syndrome (which may cause similar swelling episodes) and eosinophilia-myalgia syndrome (which features eosinophilia but alternative symptoms). Some studies have shown that edema attacks are associated with degranulation (release of enzymes and mediators from eosinophils), and others have demonstrated antibodies against endothelium (cells lining blood vessels) in the condition.

Gleich's syndrome is not a form of the idiopathic hypereosinophilic syndrome in that there is little or no evidence that it leads to organ damage. Rather, recent studies report that a subset of T cells (a special form of lymphocyte blood cell) found in several Gleich syndrome patients have an abnormal immunophenotype, i.e. they express CD3-, CD4+ cluster of differentiation cell surface antigens. These same aberrant T cell immunophenotypes are found in lymphocyte-variant eosinophilia, a disease in which the aberrant T cells overproduce cytokines such as interleukin 5 which simulate the proliferation of eosinophil precursor cells and are thereby responsible for the eosinophilia. It is suggested that most forms of Gleich's syndrome are due to a similar aberrant T cell mechanism and are a subtype of lymphocyte-variant eosinophilia.

Gleich syndrome has a good prognosis. Attack severity may improve with steroid treatment.

In October 2007 an astute medical interpreter noticed similar neurological symptoms being reported by Spanish-speaking patients seeking treatment from different physicians at the Austin Medical Center, in Austin, Minnesota. Not only did these patients share similar neurological symptoms, they also worked at the same pork processing plant. Dr. Daniel LaChance, a physician at both the Austin Medical Center and the Mayo Clinic in nearby Rochester, Minnesota, was notified. He launched a request to area physicians to refer other patients with similar symptoms to him. The Minnesota Department of Health (MDH) was notified and began an investigation into the "outbreak." The MDH identified workers from two other pork processing plants in Indiana and Nebraska who also had parallel neurological complaints. Several agencies including the Occupational Safety and Health Administration (OSHA) and the Center for Disease Control and Prevention (CDC) were brought in to assist. Simultaneously investigations were conducted to rule out contagious disease, to locate the source or carrier, and to identify what exactly was causing these workers to develop these symptoms.

Removal from exposure was the first line of treatment. Due to progressive sensory loss and weakness, immunotherapy was often required. These treatments included intravenous methylprednisolone, oral prednisone, azathioprine, and/or immunoglobulin. All 24 patients improved, including 7 who received no treatment and 17 who required immunotherapy.

Fechtner syndrome is a variant of Alport syndrome characterized by leukocyte inclusions, macrothrombocytopenia, thrombocytopenia, nephritis, and sensorineural hearing loss. Some patients may also develop cataracts.

The nerve conduction study usually provides useful information for making diagnosis. A CT scan is sometimes used to rule out some causes from the central nervous system.

Neonatal sepsis screening:

1. DLC (differential leukocyte count) showing increased numbers of polymorphs.

2. DLC: band cells > 20%.

3. increased haptoglobins.

4. micro ESR (Erythrocyte Sedimentation Rate) titer > 15mm.

5. gastric aspirate showing > 5 polymorphs per high power field.

6. newborn CSF (Cerebrospinal fluid) screen: showing increased cells and proteins.

7. suggestive history of chorioamnionitis, PROM (Premature rupture of membranes), etc...

Culturing for microorganisms from a sample of CSF, blood or urine, is the gold standard test for definitive diagnosis of neonatal sepsis. This can give false negatives due to the low sensitivity of culture methods and because of concomitant antibiotic therapy. Lumbar punctures should be done when possible as 10-15% presenting with sepsis also have meningitis, which warrants an antibiotic with a high CSF penetration.

CRP is not very accurate in picking up cases.

Over 40 laboratory tests were initially conducted to rule out various pathogens and environmental toxins. These tests were used to try to identify potential viruses carried by humans, pigs, or both, including rotoviruses, adenoviruses, hepatitis A, and hepatitis E. They also tried to identify bacteria such as salmonella and escherichia coli (e. coli), and parasites such as Giardia and cryptosporidium that could be causing the symptoms. All were ruled out.

Neurodegenerative diseases were considered specifically because of the similarity of symptoms and animal involvement thus included investigation of prion associated diseases such as bovine spongiform encephalopathy (BSE), chronic wasting disease (CWD), and variant Creutzfeldt–Jakob disease (vCJD). These all have highly transmissible pathogenic agents that induce brain damage. Since no pathogenic agent had been found, these diseases were ruled out as being related.

Next two very similar neuropathies were ruled out. Guillain–Barré syndrome (GBS) induces an acute autoimmune response which affects the Schwann cells in the peripheral nervous system. GBS is usually triggered by an infection that causes weakness and tingling that may lead to muscle loss. This condition may be life-threatening if muscle atrophy ascends to affect the pulmonary or cardiac systems. So far, no infectious agents have been found that relate to the current disease, progressive infammatory neuropathy. They looked at chronic inflammatory demyelinating polyneuropathy (CIDP) which is characterized by progressive weakness and sensory impairment in the arms and legs. Damage occurs to the myelin sheath in the peripheral nervous system. As doctors at the Mayo Clinic were beginning to note, the problem they were seeing in progressive inflammatory neuropathy was occurring in the spinal nerve roots.

Also inside standard MS different clinical courses can be separated.

Camisa disease (or Vohwinkel variant with ichthyosis) is the variant form of Vohwinkel syndrome, characterized by ichthyosis and normal hearing.

It is associated with loricrin.

It was characterized in 1984 and 1988.

Based on studies conducted in the United States, the prognosis for individuals with ALECT2 amyloidosis is guarded, particularly because they are elderly and their kidney disease is usually well-advanced at the time of presentation. End-stage renal disease develops in 1 out of 3 patients and has a median renal survival of 62 months. A suggested prognostic tool is to track creatinine levels in ALect2 patients. The attached Figure gives survival plotss for individuals with LECT2 renal amyloidosis and serum creatinine levels less than 2 mg/100 ml versus 2 mg/100 ml or greater than 2 mg/100 ml. The results show that afflicted individuals with lower creatinine levels have a ~four-fold higher survival rate.

Some NMO patients present double positive for autoantibodies to AQP4 and MOG. These patients have MS-like brain lesions, multifocal spine lesions and retinal and optic nerves atrophy.

Hyper IgM Syndrome Type 1 (HIGM-1) is the X-linked variant of the Hyper-IgM syndrome. The affected individuals are virtually always male, because males only have one X chromosome, received from their mothers. Their mothers are not symptomatic, even though they are carriers of the allele, because the trait is recessive. Male offspring of these women have a 50% chance of inheriting their mother's mutant allele.

ANOTHER syndrome consists of alopecia, nail dystrophy, ophthalmic complications, thyroid dysfunction, hypohidrosis, ephelides and enteropathy, and respiratory tract infections. This is an autosomal recessive variant of ectodermal dysplasia.