Clinical features Neck stiffness, Texas<unk>  epidemic of 1911–12 In adults, the most common symptom of<unk>  is a severe headache, occurring in almost 90% of cases of bacterial<unk> , followed by neck stiffness (the inability to flex the neck forward passively due to increased neck muscle tone and stiffness). The classic triad of diagnostic signs consists of neck stiffness, sudden high fever, and altered mental status; however, all three features are present in only 44–46% of bacterial<unk>  cases. If none of the three signs are present, acute<unk>  is extremely unlikely. Other signs commonly associated with<unk>  include photophobia (intolerance to bright light) and phonophobia (intolerance to loud noises). Small children often do not exhibit the aforementioned symptoms, and may only be irritable and look unwell. The fontanelle (the soft spot on the top of a baby's head) can bulge in infants aged up to 6 months. Other features that distinguish<unk>  from less severe illnesses in young children are leg pain, cold extremities, and an abnormal skin color. Nuchal rigidity occurs in 70% of bacterial<unk>  in adults. Other signs include the presence of positive Kernig's sign or Brudziński sign. Kernig's sign is assessed with the person lying supine, with the hip and knee flexed to 90 degrees. In a person with a positive Kernig's sign, pain limits passive extension of the knee. A positive Brudzinski's sign occurs when flexion of the neck causes involuntary flexion of the knee and hip. Although Kernig's sign and Brudzinski's sign are both commonly used to screen for<unk> , the sensitivity of these tests is limited. They do, however, have very good specificity for<unk> : the signs rarely occur in other diseases. Another test, known as the "jolt accentuation maneuver" helps determine whether<unk>  is present in those reporting fever and headache. A person is asked to rapidly rotate the head horizontally; if this does not make the headache worse,<unk>  is unlikely. Other problems can produce symptoms similar to those above, but from non-meningitic causes. This is called meningism or pseudomeningitis.<unk>  caused by the bacterium Neisseria<unk> is (known as "meningococcal<unk> ") can be differentiated from<unk>  with other causes by a rapidly spreading petechial rash, which may precede other symptoms. The rash consists of numerous small, irregular purple or red spots ("petechiae") on the trunk, lower extremities, mucous membranes, conjunctiva, and (occasionally) the palms of the hands or soles of the feet. The rash is typically non-blanching; the redness does not disappear when pressed with a finger or a glass tumbler. Although this rash is not necessarily present in meningococcal<unk> , it is relatively specific for the disease; it does, however, occasionally occur in<unk>  due to other bacteria. Other clues on the cause of<unk>  may be the skin signs of hand, foot and mouth disease and genital herpes, both of which are associated with various forms of viral<unk> . Early complications Charlotte Cleverley-Bisman developed severe meningococcal<unk>  as a young child; in her case, the petechial rash progressed to gangrene and required amputation of all limbs. She survived the disease and became a poster child for a<unk>  vaccination campaign in New Zealand. Additional problems may occur in the early stage of the illness. These may require specific treatment, and sometimes indicate severe illness or worse prognosis. The infection may trigger sepsis, a systemic inflammatory response syndrome of falling blood pressure, fast heart rate, high or abnormally low temperature, and rapid breathing. Very low blood pressure may occur at an early stage, especially but not exclusively in meningococcal<unk> ; this may lead to insufficient blood supply to other organs. Disseminated intravascular coagulation, the excessive activation of blood clotting, may obstruct blood flow to organs and paradoxically increase the bleeding risk. Gangrene of limbs can occur in meningococcal disease. Severe meningococcal and pneumococcal infections may result in hemorrhaging of the adrenal glands, leading to Waterhouse-Friderichsen syndrome, which is often fatal. The brain tissue may swell, pressure inside the skull may increase and the swollen brain may herniate through the skull base. This may be noticed by a decreasing level of consciousness, loss of the pupillary light reflex, and abnormal posturing. The inflammation of the brain tissue may also obstruct the normal flow of CSF around the brain (hydrocephalus). Seizures may occur for various reasons; in children, seizures are common in the early stages of<unk>  (in 30% of cases) and do not necessarily indicate an underlying cause. Seizures may result from increased pressure and from areas of inflammation in the brain tissue. Focal seizures (seizures that involve one limb or part of the body), persistent seizures, late-onset seizures and those that are difficult to control with medication indicate a poorer long-term outcome. Inflammation of the meninges may lead to abnormalities of the cranial nerves, a group of nerves arising from the brain stem that supply the head and neck area and which control, among other functions, eye movement, facial muscles, and hearing. Visual symptoms and hearing loss may persist after an episode of<unk> . Inflammation of the brain (encephalitis) or its blood vessels (cerebral vasculitis), as well as the formation of blood clots in the veins (cerebral venous thrombosis), may all lead to weakness, loss of sensation, or abnormal movement or function of the part of the body supplied by the affected area of the brain.
Meningitis
Lyme disease
Cerebritis
Naegleriasis
Encephalitis
Meningoencephalitis
Neuroleptic malignant syndrome
Meninges