Diagnosis
There are some laboratory tests that may aid in diagnosis of GSD-V. A muscle biopsy will note the absence of myophosphorylase in muscle fibers. In some cases, acid-Schiff stained glycogen can be seen with microscopy.Genetic sequencing of the PYGM gene (which codes for the muscle isoform of glycogen phosphorylase) may be done to determine the presence of gene mutations, determining if McArdles is present. This type of testing is considerably less invasive than a muscle biopsy.The physician can also perform an ischemic forearm exercise test as described above. Some findings suggest a nonischemic test could be performed with similar results. The nonischemic version of this test would involve not cutting off the blood flow to the exercising arm. Findings consistent with McArdles disease would include a failure of lactate to rise in venous blood and exaggerated ammonia levels. These findings would indicate a severe muscle glycolytic block. Serum lactate may fail to rise in part because of increased uptake via the monocarboxylate transporter (MCT1), which is upregulated in skeletal muscle in McArdle disease. Lactate may be used as a fuel source once converted to pyruvate. Ammonia levels may rise given ammonia is a by-product of the adenylate kinase pathway, an alternative pathway for ATP production. In this pathway, two ADP molecules combine to make ATP; AMP is deaminated in this process, producing inosine monophosphate (IMP) and ammonia (NH3).Physicians may also check resting levels of creatine kinase, which are moderately increased in 90% of patients.
In addition to the increased hearing loss, there have also been findings of resolved hearing loss after ventriculoperitoneal shunt placement, where there is a release of CSF pressure on the auditory pathways.The diagnosis of CSF buildup is complex and requires specialist expertise. Diagnosis of the particular complication usually depends on when the symptoms appear, that is, whether symptoms occur when the person is upright or in a prone position, with the head at roughly the same level as the feet.Standardized protocols for inserting cerebral shunts have been shown to reduce shunt infections. There is tentative evidence that preventative antibiotics may decrease the risk of shunt infections. Epidemiology
The hydrocephalus disease burden are concentrated in the developing world while North America and Canada has the least number of cases. A systematic review in 2019 estimated that there are 180,000 childhood hydrocephalus cases from African continent alone per year, followed by 90,000 cases from Southeast Asia and Western Pacific. Latin America also has high prevalence of hydrocephalus. However, data on hydrocephalus disease burden in adults are lacking. History
In the pre-historic area, there were various paintings or artifacts depicting children or adults with macrocephaly (large head) or clinical findings of hydrocephalus. However, due to lack of writing, it was unknown how the people thought of the disorder at that time and the ways to treat the disease.References to hydrocephalic skulls can be found in ancient Egyptian medical literature from 2,500 BC to 500 AD.