Meningitis: Types, Pathophysiology, Clinical Manifestations, and Medical Management

MENINGITIS Inflammation of the meninges which cover and protect the brain and spinal cord. 2 main types of meningitis: VIRAL AND BACTERIAL Can be SEPTIC or ASEPTIC Septic meningitis- caused by a bacteria (ex: streptococcus pneumoniae and neiserria meningitidis responsible for 80-90% of cases ) Aseptic meningitis- cause is viral or secondary to CA or weakened immune system (HIV) *occurs more freq in summer and early fall PATHOPHYSIOLOGY: Meningitis originates in 1of 2 ways : through bloodstream as a consequence of other infections or by direct spread, such as after a traumatic injury to the facial bones or secondary to invasive procedures Once the causative organism enters the bloodstream it crosses the BBB and goes into the CSF. Host immune responses stimulate the release of cell wall fragments and lipopolysaccharides facilitating inflammation of the subarachnoid and pia matter. The inflammation causes ICP. CSF circulates through the subarachnoid space where inflammatory cellular materials form the affected meningeal tissue enter and accumulate. PROGNOSIS – depends on the causative organism, severity of the infection and illness and the timeliness of treatment. CLINICAL MANIFESTATIONS: Headache along w fever and chills are the INITIAL SYMPTOMS. Fever stays high throughout the course of the illness. HA is usually steady or throbbing and very severe as a result of meningeal irritation. Older adults can have mental status changes and focal neurologic deficits. Other S/S: NECK IMMOBILITY – nuchal rigidity (stiff and painful neck) can be an early sign, and any attempts at flexion of the head are difficult because of spasms in the muscles of the neck. POSITIVE KERNIG SIGN -leg cannot be completely extended when the pt is lying w the thigh flexed on the abdomen. When the sign is bilateral, meningeal irritation is suspected. POSITIVE BRUDZINSKI SIGN – when the pts neck is flexed (After ruling our cervical trauma or injury) flexion of the knees and hips is produced, when the lower extremity of side is passively flexed , a similar movements is seen in the opposite extremity. BRUDZINSKIS SIGN IS A MORE SENSTIVE INDICATOR OF MENINGEAL IRRITATION THAN KERNIGS SIGN. ** PHOTOPHOBIA – extreme sensitivity to light. RASH – occurs in about half of all patients. Skin lesions develop ranging from a petechial rash with purpuric lesions to large areas of ecchymosis. Disorientations and memory impairment are common early in the course of illness Lethargy, unresponsiveness and coma may develop. Seizures can also occu ICP increases secondary to diffuse brain swelling or hydrocephalus. (S/S of ICP increasing – decreased LOC and focal motor deficits. ) IF not controlled, the uncus of the temporal lobe may herniate through the tentorium causing pressure on the brainstem .  this is a life threatening event that causes cranial nerve dysfunction and depresses the centers for vital functions, such as the medulla. ASSESMENT AND DX FINDINGS: CT scan – to detect shift in brain contents. Bacterial culture and gram staining of CSF and blood are key diagnostic tests Gram staining allows for rapid identification of the causative bacteria and initiation of appropriate antibiotic therapy MEDICAL MANAGEMENT : Early administration of ATB Penicillin G in combo with cephalosporins administered IV emergently during suspected meningitis Dexamethasone Fluid volume expanders tx dehydration and shock Anticonvulsant meds to tx seizures that can occur