Intraventricular Antibiotic Administration Research Articles

Clinical, Microbiological Profile, and Treatment Response to Intraventricular Antibiotics in the Management of Postneurosurgical Meningitis: A Single-Center Experience.

Postneurosurgical meningitis (PNM) is a serious medical condition with high mortality and morbidity caused by Gram positive organisms like Staphylococcus aureus and Gram-negative organisms like Acinetobacter baumannii. Optimum concentration of antibiotics in the cerebrospinal fluid (CSF) to treat these infections is difficult to achieve. Intraventricular antibiotic administration bypasses the blood-brain barrier and can achieve high CSF concentration without causing systemic toxicity. Retrospective review of all patient records were done to identify patients who developed postneurosurgical meningitis and received intraventricular antibiotic therapy during the period of July 2017 to December 2022. Demographic and clinical data along with the type of antibiotic, route, dose, and duration of administration were collected. CSF parameters before and after intraventricular antibiotic administration were collected and analyzed. Twenty-six patients with postneurosurgical meningitis received intraventricular antibiotic therapy. Intracranial tumors were the most common underlying pathology followed by aneurysms. In all, 17/26 patients had received vancomycin and 9/26 patients had received colistin. External ventricular drain was used in 17/26 cases and Ommaya reservoir was used in 9/26 cases. Six patients showed growth of organism in CSF before starting intraventricular antibiotics, while one patient remained culture positive despite treatment. Of the 26 patients, 3 died despite treatment. There were significant changes in the CSF parameters after intraventricular antibiotic therapy. Intraventricular administration of antibiotic provides an alternative therapeutic option in the management of patients who are not responding or poorly responding to systemic antibiotics.

Intraventricular endoscopy and intraventricular antibiotics in the treatment of multiloculated hydrocephalus with ventriculitis in a neonate and an infant: Two case reports

Background: We present two pediatric cases, a neonate and an infant, who presented with treatment-refractory ventriculitis and multiloculated hydrocephalus treated with simultaneous intraventricular endoscopy and antibiotics. This is the first report of this combined therapy in children. Case Description: Using intraventricular endoscopic surgery and antibiotics, hydrocephalus was treated with a minimum number of ventricular shunt systems. In addition, treatment-refractory ventriculitis was treated in both patients using intraventricular antibiotics. Conclusion: Endoscopic surgery and intraventricular antibiotic administration are useful strategies for treating multiloculated hydrocephalus and ventriculitis in children.

Dose optimisation of antibiotics used for meningitis.

Central nervous system (CNS) infections such as ventriculitis and meningitis are associated with significant morbidity and mortality. In part, this may be due to increased difficulties in achieving a therapeutic antibiotic concentration at the site of infection due to both the pharmacokinetic (PK) changes observed during critical illness and the reduced antibiotic penetration through the blood brain barrier. This paper reviews the pharmacodynamics (PD) and CNS PKs of antibiotics used for Gram-negative bacterial CNS infections to provide clinicians with practical dosing advice. Recent PK studies have shown that currently used intravenous antibiotic dosing regimens may not achieve a therapeutic exposure within the CNS, even for reportedly 'susceptible' bacteria per the current clinical meningitis breakpoints. Limited data exist for new β-lactam antibiotic/β-lactamase inhibitor combinations, which may be required for multidrug resistant infections. Intraventricular antibiotic administration, although not a new concept, has further evidence demonstrating improved patient outcomes compared with intravenous therapy alone, despite the ongoing paucity of PK studies guiding dosing recommendations. Clinicians should obtain the bacterial minimum inhibitory concentration when treating patients with CNS Gram-negative bacterial infections and consider the underlying PK/PD principles when prescribing antibiotics. Therapeutic drug monitoring, where available, should be considered to guide dosing. Intraventricular therapy should also be considered for patients with ventricular drains to optimise clinical outcomes.

Efficacy and Safety of Intraventricular Antibiotic Administration

Abstract The administration of antibiotics via intraventricular administration for treatment of central nervous system infections is an understudied topic that lacks data for specific patient outcomes regarding dosing and adverse events. A comprehensive review of the literature was performed on PubMed, MEDLINE, Scopus, and CINAHL using the following terminology: “intraventricular” OR “intraventricular drug administration” AND “antibiotic” OR “antimicrobial” AND “infection” AND “CNS” NOT “Intrathecal.” Studies that described adult human patients who received an antibiotic via intraventricular administration with complete dosing, efficacy, and safety data were included. A total of 8 studies met inclusion and were used in this review and detailed the use of antibiotics targeting resistant Gram-positive and Gram-negative bacteria. Minimal adverse effects were reported, although the determination of appropriate dosing and markers of efficacy remains elusive due to the common concomitant administration of intravenous antibiotics. Further clinical evaluation is necessary.

Intraventricular administration of antibiotics by ommaya reservoir for patients with multidrug-resistant Acinetobacter baumannii central nervous system infection

Aim To investigate whether the Ommaya reservoir can be used to treat multiple drug-resistant Acinetobacter baumannii (MDR-AB) infections in the central nervous system (CNS). Methods Retrospectively analyzed the clinical records and data of 15 MDR-AB CNS infection patients who were treated in our neuro-ICU. Four patients with MDR-AB CNS infection were involved in this study. Results We report the successful treatment of MDR-AB CNS infection by Ommaya reservoirs and intraventricular antibiotic (IVA) administration. Ommaya reservoirs allow serial CSF sampling and IVA injection. Furthermore, debridement can be performed during the operation to insert the Ommaya. Conclusion Ommaya reservoirs can be used as an effective treatment approach of MDR-AB or other multidrug-resistant Gram-negative bacteria CNS infections.

Intrathecal and Intraventricular Administration of Antibiotics in Gram-Negative Nosocomial Meningitis in a Research Hospital in Turkey.

To evaluate the gram-negative nosocomial meningitis cases which were treated with intrathecal (IT) / intraventricular (IVT) antibiotics. Medical records were reviewed for IT/IVT antibiotherapy. Gram-negative nosocomial meningitis cases treated with IT/IVT antibiotherapy additional to systemic antibiotics were included. All patients? sex, age, SOFA scores, surgical history, cerebrospinal fluid (CSF) culture results, CSF cell counts, systemic and IT/IVT antibiotics, their dosages and duration, CSF culture sterility and sterility time, 28-day mortality due to meningitis, and all other causes were recorded and analyzed. Thirteen patients were included between 2014 and 2018. Most common microorganism was Acinetobacter baumannii (A.baumannii) (8/13). IT/IVT antibiotics were chosen according to susceptibility. Colistin was used in eight patients, amikacin was used in four, and one patient used amikacin and colistin consecutively. Culture negativity could not be achieved in two patients. Eight patients clinically improved but five patients had no clinical response. 28-day mortality due to infection occured in 2 of 13 patients (15%). 28-day all-cause mortality occured in 3 of 13 patients (23%). In our study, CSF culture negativity rate was high. IT/IVT antibiotic therapy should be considered as an effective and acceptable treatment option, especially in patients who do not respond to standard IV antibiotherapy.

Meningitis in a patient with neutropenia due to Rothia mucilaginosa: a case report

BackgroundRothia mucilaginosa is a Gram-positive bacterium occurring as a commensal in the oral cavity and upper respiratory tract. Although rarely pathogenic in an immunocompetent host, it can cause severe opportunistic infections in immunocompromised individuals.Case presentationA 67-year-old white woman had a routine blood analysis before undergoing knee surgery. The results showed leukopenia for which bone marrow examination was performed, showing an underlying acute myeloid leukemia. During the neutropenic phase after a second induction with cytarabine/idarubicin, she developed fever, headaches, and photophobia. Cultures of cerebrospinal fluid were positive for Rothia mucilaginosa. Despite full therapy with antibiotics, neurosurgical interventions, and intensive care support, our patient died due to refractory intracranial hypertension and transtentorial herniation.ConclusionsMeningitis due to Rothia mucilaginosa is a rare but potentially lethal infection in patients with neutropenia, and evidence-based guidelines for the treatment of this disease are lacking. We suggest an empirical therapy with amoxicillin/rifampicin until adjustments can be made based on an antibiogram. Intrathecal or intraventricular administration of antibiotics can be considered if neurosurgical access is already obtained because of disease-associated complications.

Outcome Following the Treatment of Ventriculitis Caused by Multi/Extensive Drug Resistance Gram Negative Bacilli; Acinetobacter baumannii and Klebsiella pneumonia.

Introduction: CNS ventriculitis is a serious complication following an intracranial insult that demands immediate treatment with broad-spectrum antibiotics in a critical care setting. Infections due to multi/extensive drug resistance (MDR/XDR) microorganisms are very challenging, which may demand an additional approach to the ongoing practice; intravenous and intraventricular administration of antibiotics.Aim: To study the efficacy and safety of thorough ventricular irrigation followed by daily intraventricular antibiotic administration in patients with MDR/XDR ventriculitis.Materials and Methods: A retrospective analysis was done on 19 inpatients with ventriculitis caused by Acinetobacter baumannii (AB) or Klebsiella pneumonia (KP), at Shanghai Tenth People's Hospital from January 2016 to October 2017. We reviewed our experience; the role of thorough ventricular irrigation with Colistin mixed normal saline, followed by intraventricular Colistin therapy. Treatment outcomes were evaluated based on the clinical symptoms, Cerebro-Spinal Fluid (CSF) culture, laboratory findings and complications.Results: A total of 19 patients were included (15 males and 4 females), with a mean age in years of 51, which ranged from 18–67. Fourteen patients had Acinetobacter baumannii (AB) and 5 had Klebsiella pneumoniae (KP). The average CSF sterilization period following ventricular irrigation and intraventricular Colistin was 6 days. Sixteen patients (84%) were cured, and 3 patients (15%) died during the course of the treatment.Conclusion: In addition to Intraventricular Colistin, thorough ventricular irrigation could increase the cure rate up to 84% in patients suffering from MDR/XDR CNS ventriculitis.

Multi-systemic melioidosis: a clinical, neurological, and radiological case study from Hainan Province, China

BackgroundMelioidosis is a tropical disease caused by Burkholderia pseudomallei (B. pseudomallei). It can infect any organ system and lead to multiple abscesses. A few studies reported that central nervous system (CNS) is also involved.We present a diabetic patient with multi-systemic melioidosis that affected the CNS, thorax, and spleen. The aim was to study the clinical and radiological features of melioidosis and enhance understanding of the disease.Case presentationA 38-year-old male presented with cough and expectoration mixed with blood for several days. Chest computed tomography (CT) showed a patchy opacity in his left lung, and multiple low-density lesions in his spleen. After 10 days of antibiotics treatment, his clinical symptoms improved and he was discharged from the hospital. But 8 months later, the patient experienced sudden onset of left limb weakness and seizure and was re-admitted to the hospital. Brain CT indicated a low-density lesion over the right frontal lobe, and magnetic resonance imaging (MRI) indicated a well-enhanced lobulated lesion with multiple diffusion restriction areas in the lesion. He had a neuronavigation-guided open surgery but no malignancy was found. B. pseudomallei was cultured from the operative samples. After 4 months of systemic and intraventricular antibiotic administration treatment, he recovered complete consciousness with left hemiparesis.ConclusionsMulti-systemic melioidosis may present atypical clinical, neurological, and radiological manifestations. It is extremely important to accurately diagnose before treatment is selected. CNS melioidosis in early stage manifests similar symptoms to malignancy or stroke. It might mislead to a false diagnose. Diffusion weighted imaging (DWI) can help in differentiate abscesses from cystic tumours.

Ventriculoperitoneal Shunt Infections in Adult Patients

Ventriculoperitoneal Shunt Infections in Adult Patients

Ventriculoperitoneal Shunt Infections in Adult Patients

Ventriculoperitoneal Shunt Infections in Adult Patients

Intraventricular antibiotics for bacterial meningitis in neonates

Neonatal meningitis may be caused by bacteria, especially gram-negative bacteria, which are difficult to eradicate from the cerebrospinal fluid (CSF) using safe doses of antibiotics. In theory, intraventricular administration of antibiotics would produce higher antibiotic concentrations in the CSF than intravenous administration alone, and eliminate the bacteria more quickly. However, ventricular taps may cause harm. To assess the effectiveness and safety of intraventricular antibiotics (with or without intravenous antibiotics) in neonates with meningitis (with or without ventriculitis) as compared to treatment with intravenous antibiotics alone. The Cochrane Library, Issue 2, 2007; MEDLINE; EMBASE; CINAHL and Science Citation Index were searched in June 2007. The Oxford Database of Perinatal Trials was searched in June 2004. Pediatric Research (abstracts of proceedings) were searched (1990 to April 2007) as were reference lists of identified trials and personal files. No language restrictions were applied.This search was updated in May 2011. Selection criteria for study inclusion were: randomised or quasi-randomised controlled trials in which intraventricular antibiotics with or without intravenous antibiotics were compared with intravenous antibiotics alone in neonates (< 28 days old) with meningitis. One of the following outcomes was required to be reported: mortality during initial hospitalisation; neonatal or infant mortality, or both; neurodevelopmental outcome; duration of hospitalisation; duration of culture positivity of CSF and side effects. All review authors abstracted information for outcomes reported and one review author checked for discrepancies and entered data into RevMan 5.1. Risk ratio (RR), risk difference (RD), number needed to treat for an additional beneficial outcome (NNTB) or number needed to treat for an additional harmful outcome (NNTH), and mean difference (MD), using the fixed-effect model are reported with 95% confidence intervals (CI). The updated search in June 2011 did not identify any new trials. One study is included in the review. This study assessed the effect of intraventricular gentamicin in a mixed population of neonates (69%) and older infants (31%) with gram-negative meningitis and ventriculitis. Mortality was statistically significantly higher in the group that received intraventricular gentamicin in addition to intravenous antibiotics compared to the group receiving intravenous antibiotics alone (RR 3.43; 95% CI 1.09 to 10.74; RD 0.30; 95% CI 0.08 to 0.53); NNTH 3; 95% CI 2 to 13). Duration of CSF culture positivity did not differ significantly (MD -1.20 days; 95% CI -2.67 to 0.27). In one trial that enrolled infants with gram-negative meningitis and ventriculitis, the use of intraventricular antibiotics in addition to intravenous antibiotics resulted in a three-fold increased RR for mortality compared to standard treatment with intravenous antibiotics alone. Based on this result, intraventricular antibiotics as tested in this trial should be avoided. Further trials comparing these interventions are not justified in this population.

Fulminant ependymitis following intraventricular rupture of brain abscess

A 48-year-old man with a history of a penetrating brain injury was referred with a presumptive diagnosis of bacterial meningitis. Examination revealed a brain abscess in addition to meningitis. Blood and cerebrospinal fluid (CSF) cultures were negative for bacteria, and empirical IV antibiotic therapy with vancomycin (VCM) and meropenem was initiated. Despite initial improvement, however, his condition rapidly deteriorated into coma following intraventricular rupture of the abscess and hydrocephalus. Thereafter, an emergency ventriculostomy was performed and the abscess was evacuated. Bacterial cultures of the pus were negative. To manage the hydrocephalus, 150-200ml of CSF were drained daily. Intraventricular administration of VCM (20mg q.d.) was added to the IV antibiotic therapeutic regimen after surgery. Although the primary abscess rapidly decreased in size, ependymitis developed in the fourth ventricle. This new lesion, which resulted from CSF dissemination from the primary abscess, was refractory to treatment, and eventually disappeared after the intraventricular VCM dosage was increased from 20 to 30mg and continued for 30days. A possible reason for the development of fulminant ependymitis and why it was refractory to treatment despite the shrinkage of the primary lesion may be that physiological CSF flow from the lateral to the fourth ventricle was lost due to CSF drainage, and the stagnant CSF flow coupled with an insufficient VCM level in the fourth ventricle facilitated the rapid growth of pathogens. Although intraventricular antibiotic administration is efficacious for treating ruptured brain abscesses, it may be associated with the unexpected development of secondary lesions.

CONSERVATIVE MANAGEMENT OF PATIENTS WITH CEREBROSPINAL FLUID SHUNT INFECTIONS

In patients with cerebrospinal fluid (CSF) shunt infection, removal of the shunt and antibiotic administration is the current standard of care. In 1986, we developed a protocol for the conservative management of patients with infected but functioning shunts. Treatment was based on the administration of a combination of intraventricular and systemic antibiotics. Intraventricular antibiotics were instilled via a separate access device. The purpose of this report is to describe our experience with this therapeutic intervention. An observational study of all patients treated for CSF shunt infection between 1986 and 2003 was undertaken. Cure was defined by sterile CSF after completion of therapy and sterile shunt components at next revision or long-term freedom from recurrent infection (follow-up period, 6-88 mo). In total, 43 of 122 patients with CSF shunt infections were treated conservatively according to our protocol. Overall, 84% of these patients were cured, with a 92% success rate for patients with infections caused by bacteria other than Staphylococcus aureus. This included 30 coagulase-negative staphylococcal infections, of which two were treatment failures. We abandoned conservative treatment of patients with Staphylococcus aureus infections after early experience demonstrated that the success rate (four treatment failures in seven patients) was markedly lower than that for other pathogens. During the treatment and follow-up periods, there were three deaths, two of which were unrelated to shunt infection; treatment failure could not be completely excluded in the remaining patient. There was no toxicity related to intraventricular antibiotic administration. The incidence of shunt blockage among patients who were treated conservatively was not significantly different from that among a large cohort of patients with uninfected shunts. Ten patients received part of their courses of treatment as outpatients. The success rate of conservative management of patients with CSF shunt infections caused by coagulase-negative staphylococci is comparable with those in the published literature for patients treated conventionally. This form of management avoids surgical intervention, with its attendant risks, and is safe.

Surgical shunt infection: significant reduction when using intraventricular and systemic antibiotic agents

Infection represents the most common serious complication of shunt surgery, and typically its incidence ranges between 5 and 15%, despite the use of systemic antibiotic agents. Because systemic antibiotic medications generally penetrate the cerebrospinal fluid (CSF) poorly, the authors investigated, in a controlled study, whether the addition of intraventricular antibiotic treatment decreases the incidence of perioperative infection in adult patients. Data pertaining to all CSF shunt procedures conducted at the authors' institution during an 11-year period were reviewed. Perioperative infection was defined as culture-positive CSF and the clinical presence of infection-related symptoms occurring within 90 days of surgery. All patients underwent intraoperative systemic antistaphylococcal antibiotic therapy. Before May 16, 1999, the senior author (R.H.S.) also administered 4 mg of gentamicin intraventricularly at surgery (Group I); thereafter, 10 mg of vancomycin was additionally administered (Group II). Other neurosurgeons at this institution did not use intraventricular antibiotic therapy, and their patients served as additional controls in identical time periods (Groups III and IV). A total of 802 shunt procedures were performed in 534 patients. Control infection rates were 5.4% (eight of 147) in Group I; 6.2% (nine of 145) in Group III; and 6.7% (18 of 267) in Group IV. With the combination of systemic antibiotic and intraventricular gentamicin and vancomycin (Group II), the infection rate fell significantly to 0.4% (one of 243). No complications were noted in association with intraventricular antibiotic administration. The combination of intraventricular gentamicin and vancomycin with systemic antibiotic therapy significantly decreased the incidence of perioperative shunt infection. It is presumed that intraventricular antibiotic therapy extends prophylactic antibiotic coverage into the CSF and prevents bacterial seeding.

Conservative Management of Patients with Cerebrospinal Fluid Shunt Infections

In patients with cerebrospinal fluid (CSF) shunt infection, removal of the shunt and antibiotic administration is the current standard of care. In 1986, we developed a protocol for the conservative management of patients with infected but functioning shunts. Treatment was based on the administration of a combination of intraventricular and systemic antibiotics. Intraventricular antibiotics were instilled via a separate access device. The purpose of this report is to describe our experience with this therapeutic intervention. An observational study of all patients treated for CSF shunt infection between 1986 and 2003 was undertaken. Cure was defined by sterile CSF after completion of therapy and sterile shunt components at next revision or long-term freedom from recurrent infection (follow-up period, 6-88 mo). In total, 43 of 122 patients with CSF shunt infections were treated conservatively according to our protocol. Overall, 84% of these patients were cured, with a 92% success rate for patients with infections caused by bacteria other than Staphylococcus aureus. This included 30 coagulase-negative staphylococcal infections, of which two were treatment failures. We abandoned conservative treatment of patients with Staphylococcus aureus infections after early experience demonstrated that the success rate (four treatment failures in seven patients) was markedly lower than that for other pathogens. During the treatment and follow-up periods, there were three deaths, two of which were unrelated to shunt infection; treatment failure could not be completely excluded in the remaining patient. There was no toxicity related to intraventricular antibiotic administration. The incidence of shunt blockage among patients who were treated conservatively was not significantly different from that among a large cohort of patients with uninfected shunts. Ten patients received part of their courses of treatment as outpatients. The success rate of conservative management of patients with CSF shunt infections caused by coagulase-negative staphylococci is comparable with those in the published literature for patients treated conventionally. This form of management avoids surgical intervention, with its attendant risks, and is safe.

Therapeutic vancomycin monitoring in children with hydrocephalus during treatment of shunt infections

Background The successful treatment of shunt infections in children with hydrocephalus is still an important problem. Diagnosis of shunt colonization is often very difficult. To treat serious central nervous system (CNS) infections, intraventricular therapy with antibiotics is necessary to reach adequate cerebrospinal fluid (CSF) concentrations and eradicate the infection. For optimal management of shunt infections the concentration of administered antibiotics in CSF should be measured. The antibiotic dosing could be modified in the individual patient after pharmacokinetic studies. Methods In our studies, vancomycin was applied to 10 children with hydrocephalus (including 6 with a myelomeningocele) for therapeutic purposes in shunt infections. The drug was administered IV and/or intraventricularly. During treatment the concentration of vancomycin in CSF was determined by fluorescence polarization immunoassay (FPIA) method. Results Considerable differences in vancomycin concentrations after the same intraventricular antibiotic administration were observed depending on the patient. The vancomycin levels determined at study state were often much higher than the therapeutic recommended range, and the biologic half-life period (T 1/2) of vancomycin in cerebrospinal fluid after intraventricular administration was prolonged. Conclusions The results of our studies give information about the pharmacokinetics of vancomycin in CSF in a group of children with hydrocephalus after intraventricular administration of the drug. In our investigation, the administration of doses smaller than 5 mg/24 hours is appropriate when the removed volume of CSF will be 20 to 30 mL/24 hours.

119 IN VITRO NEURÖTOXICITY OF ANTIBIOTICS

Prediction, measurement, and monitoring of neurotoxicity of antibacterial agents are extremely difficult. We studied the effects of antibiotics on growth and differentiation in dissociated rat brain cell cultures. Drugs were added from 7 to 14 days in cultures (DIC) in order to attain concentrations representing 10 and 2 times the levels reached by intraventricular antibiotic administration. At DIC 14, 21 and 24 the following evaluations were performed and compared to controls: content of protein and DNA reflecting cell growth, two enzymes of brain cell differentiation and staining for oligodendrocytes and astrocytes. No effects showed penicillin G, amoxicillin, sulbactam, aztreonam and chloramphenicol. Only marginal and always reversible influences produced ceftriaxone, vancomycin and ciprofloxacin. Clear inhibition of both cell growth and cell differentiation with only partial or absent regeneration was induced by cefepime, ceftazidime, cefotaxime, cefuroxime, imipenem, temafloxacin and amikacin. These results are in accordance with other in vitro experiments (bone marrow cells, fibroblasts) and also with clinical findings. We conclude that the sensible use of this model on the cellular level can predict potential neurotoxicity of antimicrobial agents.

Coombs positive hemolytic anemia in congenital rubella

tered antibiotics. '~ Ampicillin, which attains a relatively high intraventricular concentration during acute meningitis, may penetrate poorly when inflammation is not so extensive. ' Lumbar intrathecal treatment does not enhance resolution of ventriculitis or produce increased intraventricular concentrations of antibiotics. ~ Uncontrolled studies of intraventricular instillation of antibiotics have been encouraging. 1.~ The Neonatal Meningitis Cooperative Study Group and others recommend that an infant with continued positive CSF culture for two to three days should be suspected of having ventriculitis, and treated with both parenteral and intraventricular administration of antibiotics. ~. ~ McCracken ' recommends a ventricular tap if lumbar puncture demonstrates microorganisms after 24 hours of treatment. When ventriculitis is present, he suggests intraventricular administration of an aminoglycoside. Cerebral infarction is another complication of meningitis and ventriculitis, resulting from vasculitis. Vasoconstriction and luminal narrowing secondary to arterial inflammation have been described, which may progress to thrombosis? Diffuse cerebral edema with vascular congestion and stasis may produce venous infarction.' In this patient, computed tomography was of value in diagnosis and management of the complications of neonatal meningitis by accurate, noninvasive delineation of infarction, ventricular size, web formation, and loculation. It is particularly important, when septation has already produced loculation that shunts be placed in all portions of the cysts. These can be identified b.y the computed tomogram.