title: Halo pin intracranial penetration and epidural abscess in a patient with a previous cranioplasty: case report and review of the literature.
abstract: METHODS
  Report of a patient with an epidural abscess after halo pin intracranial penetration at the site of a previous cranioplasty.
  
  
  OBJECTIVE
  To report a rare case of intracranial penetration at the site of a previous cranioplasty associated with epidural abscess, and to discuss the diagnostic and therapeutic approach to its management.
  
  
  BACKGROUND
  The most serious complications associated with use of halo device occur when pins penetrate the inner table of the skull, resulting in cerebrospinal fluid leak and rarely in an intracranial abscess. However, no mention of intracranial halo pin penetration at the site of a previous cranioplasty was found in the literature.
  
  
  METHODS
  A 64-year-old man with ankylosing spondylitis had a halo vest placed for management of a fracture dislocation through the C5-C6 intervertebral disc space associated with left C6 radiculopathy. One week later, the patient experienced fever and headache associated with pain, redness, and drainage at the site of the insertion of the left posterior pin. Computed tomography of the brain showed a 1.5-cm intracranial penetration of the halo pin through a previous cranioplasty of the temporal bone, associated with epidural abscess and cerebral edema in the left temporoparietal lobe. The pins and the halo vest were removed, the pin site was cleaned, and a Philadelphia cervical collar was applied. Staphylococcus epidermidis grew on the culture of drainage from the pin site. The patient started immediate intravenous antibiotic treatment for 2 weeks, followed by oral antibiotics for 2 additional weeks.
  
  
  RESULTS
  The patient had gradual improvement of his symptoms within the first 48 hours. At the latest follow-up visit, he had fully recovered and his fracture had healed.
  
  
  CONCLUSIONS
  The halo device should not be used for patients with a previous cranioplasty, especially if the pins cannot be inserted at other safe areas of the skull. A thorough medical history and physical examination of the skull are important before the application of a halo device. Computed tomography of the skull may be necessary before elective halo application for patients with concomitant head trauma, confusion, or intoxication and for patients with a previous cranioplasty to ascertain the safest pin sites.
authors.affiliation: First Orthopaedic Department, Athens University Medical School, Athens, Greece. pip@hol.gr
authors.forename: P J
authors.initials: PJ
authors.lastname: Papagelopoulos
authors.forename: G S
authors.initials: GS
authors.lastname: Sapkas
authors.forename: K T
authors.initials: KT
authors.lastname: Kateros
authors.forename: S A
authors.initials: SA
authors.lastname: Papadakis
authors.forename: J A
authors.initials: JA
authors.lastname: Vlamis
authors.forename: M E
authors.initials: ME
authors.lastname: Falagas
mesh_terms: D000900:Anti-Bacterial Agents / Q000627:therapeutic use; D001858:Bone Nails / Q000009:adverse effects*; D002574:Cervical Vertebrae / Q000293:injuries / Q000601:surgery; D003399:Craniotomy; D020802:Epidural Abscess / Q000000981:diagnostic imaging / Q000188:drug therapy / Q000209:etiology* / Q000473:pathology; D006801:Humans; D007405:Intervertebral Disc Displacement / Q000150:complications / Q000601:surgery; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009989:Orthotic Devices / Q000009:adverse effects*; D011183:Postoperative Complications / Q000000981:diagnostic imaging / Q000209:etiology* / Q000473:pathology; D011843:Radiculopathy / Q000209:etiology / Q000601:surgery; D011859:Radiography; D012886:Skull / Q000601:surgery; D016103:Spinal Fractures / Q000150:complications / Q000601:surgery; D013203:Staphylococcal Infections / Q000150:complications / Q000382:microbiology / Q000473:pathology; D013212:Staphylococcus epidermidis / Q000302:isolation & purification; D014143:Traction / Q000009:adverse effects
chemical_list: D000900:Anti-Bacterial Agents