Postoperative subdural empyema caused by Propionibacterium acnes - a report of two cases

B ritish Journal of N eurosurgery 1996;10(3):321± 323

S HORT REP ORT

Postoperative subdural em pyem a caused by Propionibacterium acnesÐ a report of tw o cases G. CRITCHLEY & R. STRACHAN

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D epartm ent of N eurosurgery, H ope Hospital, Salford, UK

A bstract Two patients with postoperative subdural empyema following burr hole evacuation of chronic subdural haem atoma are reported, both caused by Propionibacterium acnes. The need to consider this diagnosis in patients developing recurrent symptoms after surgical drainage of chronic subdural haematoma is emphasized. K eyw ords: Propionibacterium acnes, subdural empyem a.

Introduction Postoperative subdural em pyem a is a well recognized com plication follow ing craniotom y. 1 Its clinical presentation and course is m uch m ore indolent than that of an acute prim ary subdural empyem a owing to the presence of an inner lim iting m embrane. Postoperative subdural empyem a following burr hole drainage has not been widely reported. T he usual causative organisms cultured from postoperative subdural empyem a are Streptococci sp., Staphylococcus aureus and S. epidermidis. Propionibacterium acnes, although a ubiquitous m ember of skin ¯ ora has only rarely been im plicated in central nervous system infections 2 and not as the prim ary pathogen in subdural empyem a. W e present two cases of postoperative subdural em pyem a following burr hole drainage of chronic subdural haem atom a in which the prim ary causative agent was P. acnes. C ase report C ase 1 A 67-year-old right-handed m an presented with a 4-m onth history of frontal headaches, dizziness, right hand and leg clum siness and an interm ittent unsteady gait. T here was no history of head traum a. H e had a past history of two myocardial infarctions. O n exam ination he was alert and orientated with no dysphasia or cranial nerve abnorm alities, but with increased tone in the right leg. CT showed a large

F IG . 1. Case 1: plain CT scan on initial presentation showing large left chronic subdural hypodense collection with compression of the ipsilateral ventricle and m idline shift.

left tem poroparietal hypodense ¯ uid collection causing 8 m m of midline shift (Fig. 1). At operation tw o burr holes were m ade, the dura-

Correspondence to: Giles Critchley, Departm ent of Neurosurgery, Hope Hospital, Stott Lane, Salford M 6, U K. Received for publication 22nd April 1995. Accepted in revised form 7th July 1995. 0268-869 7/96/030321 ± 03 $7.50 Ó

T he Neurosurgical Foundation

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G. Critchley & R. Strachan

F IG . 2. Case 1: plain CT scan prior to aspiration of pus showing post operative intracranial air and loculation in the subdural collection.

opened and chronic subdural haem atom a ¯ uid drained. Apart from postoperative angina, he made a good postoperative recovery. O ver the following 5 w eeks he presented tw ice with a recurrence of the initial sym ptom s of headache, lethargy and hand clum siness. Repeat CT show ed a gradually increasing `residual’ collection (Fig. 2). O n his third presentation he had developed a right leg weakness, but rem ained apyrexial w ith a w hite cell count of 11.3 3 10 9 /1 and with an erythrocyte sedim entation rate (ESR) of 88 m m /h. Aspiration of ¯ uid through the previous burr hole produced pus. T his grew P. acnes, sensitive to vancom ycin and ceftriaxone. In view of his ischaem ic heart disease operative intervention was deferred and he was treated with intravenous vancomycin and ceftriaxone for three weeks. Repeat C T w as perform ed after 3 weeks which showed a marked increase in the size of the collection. He underwent a left lateral craniotom y and decortication of the subdural empyem a, and proceeded to m ake a good recovery, with resolution of the subdural collection on C T perform ed 6 weeks later.

ing aspirin for atrial ® brillation. O n examination she was fully conscious, alert and orientated, w ith a M RC grade 4 weakness of her left lower lim b and an extensor plantar response. C T of the brain revealed a hypodense well localized left frontal chronic subdural haem atom a (Fig. 3). One week after stopping her aspirin, she underw ent burr hole drainage of the collection through a single burr hole under local anaesthetic. She m ade an uneventful postoperative recovery. T wo weeks later she com plained of m ild frontal headache and interm ittent paraesthesia of her right hand. She otherw ise rem ained well and was discharged hom e having restarted her aspirin therapy. She w as readm itted after a further 2 w eeks with a progressive right hem iparesis and a m inim al dysphasia. Interestingly, her headaches had resolved. C T showed a larger low density subdural collection with som e mass effect and low attenuation in the adjacent w hite matter (Fig. 4). Planned further evacuation was deliberately delayed after stopping her aspirin therapy, but rapid progression of her hem iparesis and dysphasia forced an earlier operation after four days. She had rem ained apyrexial with a preoperative white count of only 8.7 3 10 9 /1, but an ESR of 70 m m/h. Reopening of the previous burr hole revealed pus and a craniotom y was carried out evacuating the em pyem a. Subsequent culture identi® ed P. acnes and Lactococcus sp., sensitive to several antibiotics including penicillin and cefotaxim e. On this treatm ent she m ade a rapid clinical recovery with gradual resolution of any persistent collection on follow up im aging over the next 6 w eeks.

C ase 2 A 70-year-old woman was admitted with a 1-m onth history of m ild frontal headaches, losing balance and dragging of her left leg. T here was no recent history of traum a. She had a past history of hypertension and a previous m yocardial infarction. She w as tak-

F IG 3. Case 2: plain CT scan showing left subdural collection with effacem ent of the sulci.

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Postoperative subdural empyema

F IG 4. Case 2: plain CT scan prior to aspiration of pus showing diffuse low density areas in the white matter underlying the subdural collection.

D iscussion T he indolent course of postoperative subdural em pyem a is illustrated by the ® rst patient. In both cases there was a prolonged course betw een initial surgery and ® nal diagnosis. N either patient was at any tim e system ically unwell, pyrexial nor had a w hite blood count above 12.0 3 10/l9 . T he classical features of an acute subdural empyem a, nam ely fever, altered conscious level and neck stiffness were not present. Seizures, w hich m ay occur in up to 63% of cases of acute subdural empyem a, 3 were not a feature of our tw o patients. T he absence of these classical features may be due both to the presence of an inner lim iting mem brane, clearly seen at operation, and to the low pathogenicity of P. acnes, a norm al skin com m ensal. Propionibacterium acnes has rarely been described as a prim ary cause of intracranial infections, 2,4 usually being found in m ixed ¯ ora associated with dental abscesses. 5 Richards et al. 2 describe three cases of intracerebral abscess caused by P. acnes, two following craniotom y and one follow ing traum a. Propionibacterium acnes is a gram positive anaerobic bacillus which requires prolonged culture, thus leading to underdiagnosis. Although it is a comm on skin com mensal, system ic infections are rare, occurring usually as the result of a breach in the skin defences or colonization of foreign body im plants. Sim ilar in pathogenicity to S. epidermidis it is therefore surprising that is not as well recognized as a prim ary cause of postoperative subdural empyem a. Postoperative subdural empyem a has been de-

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scribed following craniotomy, but has rarely been associated with burr hole drainage of chronic subdural haem atom a. 1,6 Presum ably, the lim ited procedure m inim izes tissue traum a and reduces the extent of the bacterial inoculum . Antibiotic prophylaxis was not used in either case although follow ing the recent W orking Party recom m endations it has now been adopted for clean nonim plant procedures. 7 The superiority of craniotom y over burr holes for the treatm ent of subdural em pyem a has been well docum ented. 8 In acute subdural em pyem a it allows direct rem oval of pus from an extensive area including the interhemispheric ® ssure. In our ® rst case craniotom y allowed access through thick granulation tissue to a pus ® lled cavity. O nce craniotom y had been perform ed both patients m ade a good recovery. In our cases, no preoperative diagnosis of subdural empyema w as m ade. T he dif® culty in m aking this diagnosis has been previously described.1 W ith hindsight, CT offered som e clues to an alternative diagnosis. In the ® rst case there w as som e loculation of the subdural collection and an increase in the density of the collection, without evidence of recent haem orrhage (Fig. 2). In the second case, low attenuation in the adjacent white matter was noted (Fig. 4). H owever, none of these features are pathognom onic for subdural empyem a. T hese cases therefore emphasize the need to entertain a diagnosis other than a residual subdural collection. Contrast CT and an ESR need also to be considered.

A cknowledgem ents W e thank M r C . G . H. W est and M r F. A. Strang for allowing us to report on their patients.

References 1 Post EM , Modesti LM . `Subacute’ postoperative subdural em pyema. J N eurosurg 1981;55:761± 5. 2 Richards J, Ingham HR, Crawford PJ, Sengupta RP, Mendelow AD. Focal infections of the central nervous system due to Propionibacterium acnes. J Infect 1989;18:279± 82. 3 Cowie R, William s B. Late seizures and morbidity after subdural empyem a. J N eurosurg 1983;58 :569± 73. 4 Sprott M S, Hall K, Newm an PK, Welbury RR, Ingham HR. Subdural abscess secondary to covert dental sepsis. Postgrad M ed J 1981;57:649± 51. 5 Mirdha BR, Kumar P. Primary anaerobic bacterial meningitis caused by Propionibacterium acnes. Postgrad M ed J 1993;69 :499± 500. 6 Luken M G, Whelan MA. Recent diagnostic experience with subdural empyema. J Neurosurg 1980;52 :764± 71. 7 Infection in Neurosurgery Working Party of the British Society for Antimicrobial Chemotherapy. Antimicrobial prophylaxis in neurosurgery and after head injury. Lancet 1994;34 4:1547± 51. 8 William s B. Subdural empyema. In: KrayenbuÈ hl H (ed.) A dv ances and technic al standards in neurosurgery , Vol 9. Vienna: Springer-Verlag, 1983;13 3± 70.

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