In meningitis, the barrier is disrupted, so once viruses have entered the brain, they are isolated from the immune system and can spread. This leads to elevated intracranial pressure, cerebral edema, meningeal irritation, and neuronal death. Diagnosis
The diagnosis of viral meningitis is made by clinical history, physical exam, and several diagnostic tests. Kernig and Brudzinski signs may be elucidated with specific physical exam maneuvers, and can help diagnose meningitis at the bedside. Most importantly however, cerebrospinal fluid (CSF) is collected via lumbar puncture (also known as spinal tap). This fluid, which normally surrounds the brain and spinal cord, is then analyzed for signs of infection. CSF findings that suggest a viral cause of meningitis include an elevated white blood cell count (usually 10-100  cells/µL) with a lymphocytic predominance in combination with a normal glucose level. Increasingly,  cerebrospinal fluid PCR tests have become especially useful for diagnosing viral meningitis, with an estimated sensitivity of 95-100%. Additionally, samples from the stool, urine, blood and throat can also help to identify viral meningitis. CSF vs serum c-reactive protein and procalcitonin have not been shown to elucidate whether meningitis is bacterial or viral.In certain cases, a CT scan of the head should be done before a lumbar puncture such as in those with poor immune function or those with increased intracranial pressure.
Recent research suggests that specific social difficulties may be a result of impaired face processing. The unusual social behavior in childhood often resembles that of an autism spectrum disorder.Other characteristics sometimes associated with callosal disorders include seizures, spasticity, early feeding difficulties and/or gastric reflux, hearing impairments, abnormal head and facial features, and intellectual disability. Associated brain anomalies
Brain anomalies that can sometimes occur in syndromes that cause callosal disorders include:
Aplasia of the cerebellar vermis
Chiari malformation
Colpocephaly
Dandy–Walker syndrome
Holoprosencephaly
Hydrocephalus
Neuronal migration disorders such as grey matter heterotopia
Schizencephaly

Associated syndromes and conditions
Some syndromes that frequently include ACC are:
Acrocallosal syndrome
Aicardi syndrome
Andermann syndrome
Donnai–Barrow syndrome
Dwarfism
FG syndrome
L1CAM syndrome
Microcephalic osteodysplastic primordial dwarfism type II
Mowat–Wilson syndrome
Oculocerebrocutaneous syndrome
Saal Bulas syndrome
Septo-optic dysplasia (optic nerve hypoplasia)
Shapiro syndrome
Vici syndromeSome conditions that can sometimes be associated with ACC or other callosal disorders include:
1p36 deletion syndrome
13q deletion syndrome
CDK13-related disorder
Craniofacial abnormalities and other oral and maxillofacial pathologies
Fetal alcohol syndrome
Fetal warfarin syndrome
Genitopatellar syndrome
Gomez-Lopez-Hernandez syndrome
Joubert syndrome
Lujan–Fryns syndrome
Marden–Walker syndrome
Maternal nutritional deficiencies or infections
Metabolic disorders
Okamoto syndrome
Opitz G/BBB syndrome
Pascual-Castroviejo syndrome
Pitt–Hopkins syndrome
Sensenbrenner syndrome
Strømme syndrome
Triploid syndrome
Trisomy 9
Xia-Gibbs syndrome

Causes
Agenesis of the corpus callosum is caused by disruption to development of the fetal brain between the 3rd and 12th weeks of pregnancy. In most cases, it is not possible to know what caused an individual to have ACC or another callosal disorder. However, research suggests that some possible causes may include chromosome errors, inherited genetic factors, prenatal infections or injuries, prenatal toxic exposures, structural blockage by cysts or other brain abnormalities and metabolic disorders.