Pneumocephalus consequent to staphylococcal pneumonia and meningitis.

Pneumocephalus is a rare condition, characterized by the presence of gas in the cranial cavity, resulting from trauma, tumors and surgical or diagnostic procedures. Intracranial infection, without any predisposing factor like trauma or surgical intervention as a cause of pneumocephalus is relatively uncommon. While, intracranial infections by gas producing organisms as a cause of pneumocephalus are well known, a spontaneous intracranial infection caused by Staphylococcus aureus causing pneumocephalus is little known. We report here a child who developed pneumocephalus following staphylococcal lung infection with meningitis and eventually showed complete recovery. Meningitis should be considered as a possible cause of pneumocephalus in absence of trauma and surgical intervention.

Introduction

Pneumocephalus is defined as the presence of gas within the cranial cavity. Gas in the cranial cavity commonly results from trauma,[1] tumor,[2] after surgery,[2] following diagnostic procedures[3] and rarely from infection.[4] Pneumocephalus occurring with meningitis is well described, its occurrence in Staphylococcal meningitis is rare. A case of pneumocephalus associated with meningitis and empyema caused by Staphylococcus aureus, which was managed successfully, is reported here.

Case Report

A twelve year old female child presented with fever, headache, back and neck pain, vomiting and cough of 20 days duration. She also had abnormal behaviour for the last 10 days. Fever was moderate to high grade and was associated with dry cough and mild chest pain. There was no history of any head trauma, seizures or any ear or nose problem. On general examination, the child was stuporous, mildly febrile with pulse 110/minute, Respiration rate (RR) – 24/minute and Blood pressure (BP) – 130/90 mm Hg . On chest examination, impaired breath sounds with crepitations were heard on both sides. On examination of the Central Nervous System (CNS), pupils were normal in size and reaction, but meningeal signs (neck rigidity and Kernig's sign) were present. Therefore, a provisional diagnosis of meningitis with pneumonia was made and the child was investigated accordingly.

Her blood examination showed Hemoglobin (Hb) – 9 g/dL, total leucocyte count (TLC) – 21.4 ×103/μL (Neutrophils (N) – 89% and Lymphocytes (L) – 11%) and chest radiograph revealed lower lobe consolidation on the left side and patchy consolidation on the right side. The child underwent a computed tomography (CT) brain scan study, followed by Cerebrospinal fluid (CSF) examination. The CT scan showed bilateral diffuse pneumocephalus, including air in the ventricles with no bony abnormalities, any communication with sinuses or any evidence of a space occupying lesion [Figures 1 and 2]. CSF study revealed - glucose 42 mg/dL, proteins 198 mg/dL, cells – 900/μL (N – 80%, L – 20%) and Adenosine Deaminase (ADA) < 5 IU. However, Gram's staining was negative and no organism was grown on culture. Enzyme-linked immunosorbent assay (ELISA) test for Human immunodeficiency virus (HIV) was negative. Her serum electrolytes were normal. She was put on empirical antimicrobial therapy along with supportive treatment.

Figure 1

Brain computed tomography scan showing multiple hypodense areas of air densities in parenchyma

Figure 2

Brain computed tomography scan of temporal region showing hypodense areas suggestive of pneumocephalus

After three days of admission, she developed bilateral pleural effusion. Pleural fluid was purulent; it showed Gram positive cocci on staining and Staphylococcus aureus grown on culture. Her treatment was modified according to sensitivity - to vancomycin (60mg/kg/day, intravenous), ceftriaxone (100mg/kg/day, intravenous) and levofloxacin (10mg/kg/d, orally). Besides the antimicrobial coverage, she was put on intercostal drainage. Her pyothorax resolved within 5 days and the child also showed overall improvement. However, the treatment was continued for two weeks and the child continued to register significant clinical improvement. Her CSF examination and CT scan, repeated after two weeks, were normal and the chest radiograph also showed resolution of pneumonia. She has been found symptom free on regular follow up.

Discussion

In the present case, there is clear evidence of pneumocephalus along with meningitis and lung infection (pneumonia and empyema). Though no organism was grown on CSF culture, the pleural fluid did show the growth of Staphylococcus aureus, indicating that the meningitis in all probability was caused by the same organism, i.e., Staphylococcus aureus. In a review of 290 patients of pneumocephalus by Markhan,[5] while infection was responsible in 8.8% cases only, trauma was the principle etiological factor (73.9%), other factors being tumors (12.9%) and surgical intervention (3.7%). CT scan of paranasal sinuses and of temporal region failed to reveal any congenital bony deformity or breach in the cribriform plate/sphenoid sinus which could be responsible for pneumocephalus. Lumbar puncture as a possible cause of pneumocephalus can safely be ruled out in this case, as it had been noticed on CT scan of brain before doing lumbar puncture. The presence of pneumocephalus in the absence of injury or surgery should raise the suspicion of infection of central nervous system.

Pneumocephalus is a known, though rare, complication of meningitis, particularly if caused by gas forming organisms[467] e.g., Clostridium perfringens, Bacteroids fragilis, E.coli, Klebsiella aerogens, Enterobactor cloacae and by mixed aerobic – anaerobic infections. Maliwan N described a case of pneumocephalus in an adult, with bacterial meningitis caused by mixed aerobic-anaerobic organisms, in the absence of any predisposing factor.[4] Penrose-Stevens et al., reported localised pneumocephalus in a case of fatal Clostridium perfringens meningitis, occurring four months after craniotomy.[8]

Staphylococcus aureus meningitis is usually associated with penetrating cranial trauma, or a neurosurgical intervention, like craniotomy or CSF shunt placement, and less frequently with hematogenous spread from any localised infection eg endocarditis, pneumonia, skin and soft tissue infection, urinary tract infection (UTI), sinusitis, otitis media or an epidural/paraspinal abscess.[9] Staphylococcus aureus has been implicated in the causation of several disorders associated with gas formation in various body tissues, e.g. gas gangrene and necrotising fasciitis.[10] A few cases in literature have been described where pneumocephalus is directly attributed to Staphylococcus aureus meningitis. However, in none of those cases, the organism could be grown on CSF; it was grown on other body fluids, e.g., ear discharge, indicating thereby an indirect evidence.[11] The present case appears similar, as the organism was grown on culture of the pleural fluid, but not on the CSF. This is not unexpected, as in a majority of meningitis cases, no organism can be isolated either on smear examination or on culture, the reasons being initiation of antibiotics in most of the cases before the laboratory examination and possibly, the use of less refined laboratory techniques.[1213]

Treatment of pneumocephalus depends on the clinical condition of the patient, the degree and progression of air collection and of course the etiology. Most cases resolve with conservative treatment and close monitoring. Surgical intervention is usually not indicated, unless there is continued CSF leak or progression of pneumocephalus to a tension condition.[14] In the present case too, the pneumocephalus resolved completely within a few weeks.