AVMs of the Posterior Fossa

1. AVMs of the Posterior Fossa Case Presentation and Literature Discussion Christopher Showers Columbia University College of Physicians and Surgeons

2. Patient CP - HPI • USH eating dinner  sudden onset very severe R H/A with lightheadedness, nausea • Progressive lethargy  LOC en route to CCH • Upon Arrivals: Decorticate Posturing Intubated; CT head acquired • Emergent R Frontal EVD  transfer MGH

3. Outside H-CT 8/14/13 21:13

4. Patient CP - MGH • Exam: • Intubated, sedated, no follow commands • L anisocoria (4/3mm)  nonreactive b/l, (-)corneals, (-)OCR, (+)cough, flexion RUE, TF in LLE • GCS: 4-5 • Labs: Na 123; K 5.7 • Drips: Mannitol x1; 23% NaCl x2  3% NaCl • EVD: at 0, open  no drainage • Repeat CT Head: interval mild progression of hemorrhage, hydrocephalus

5. Patient CP • PMx: L Humoral fracture 1.5wk ago • Meds: ASA 81mg qD; Duloxetine 60mg qD • ROS: L arm pain; no complaints prior • SHx: retired teacher, nonsmoker, active at b/l • FHx: no sudden bleeds

6. PreopAngio 8/15/13 08:30 Right Vertebral Injections

7. Operative Resection • SMG  2-3 (1-2S, 1E, 0V) • SOC  evacuation of hemorrhage / resection of AVM; placement of R occipital EVD • Washout of subdural blood • Ligated feeding arteries, identified abnormal superior vein draining AVM • Another nidus identified  anterior superior, not visualized on angio

8. IntraopAngio 8/15/13 17:02 Right Vertebral Injections

9. Operative Resection x2 • Rentered initial craniectomy site • Wider area of dissection  extensive & diffuse abnormal vessels draining into large vein extending superiorly • Skeletonized large vein with generous R cerebellar resection  Witnessed to turn blue • NICU

10. Post-op H-CT 8/15/13 21:38

11. Post-op Exam • Pupils symmetric, reactive 32mm b/l • No OCR, vertical bobbing • Mild cough reflex • UE: withdraw to pain b/l • LE: TF b/l • Deteriorated to extensor posturing UE/LE b/l • Expired on 8/21/13 01:35am

12. Posterior Fossa AVMs • 7.5% - 20.0% of all intracranial AVMs (da Costa 2009; Drake 1986; Perret 1966) • 72.4% Cerebellar / 21.5% Brainstem (da Costa 2009) • Vermian most common (Sampson 2004) • Arterial Input  distal SCA & distal PICA b/l • Large or involving 4th V  deep AICA feeders • Venous Drainage  Superiorly to Galenic System

13. Presentation of PF-AVMs • Greater Rate of Hemorrhage in PF-AVMs • Hemorrhage as presenting symptoms ~90% vs. 29-54% in ST (Khaw 2004; Stefani 2002; Drake 1986; Solomon 1986) • Smaller size vs. ST  increased hemorrhage risk (Drake 1986; Sampson 1986; Kader 1994; Langer 1998) • Greater Rate of AA  25% vs. 5-8% in ST (Sampson 1997; Lanzino 1999) • Bleeds more frequent and FATAL up to 66.7%(Fults and Kelly 1984; Batjer 2009; Symon 1995 • Rebleeding in 6.0% - 17.8%, 34.3% Dw/DD(Mast 1997; Stapf 2006; Steinberg 2008) • 5-6% annual risk up to 5 years (Halim 2004) vs. 3-4% ST (Baskaya 2006)

14. Presentation of PF-AVMs • Rarely present with Seizure • 2/68 (2.9%)  attribute to hydrocephalus (Yasargil 1998) • General Neuro deficits / CN palsy  up to 28% (Batjer 2009; Stahl 1980) • Mass effect • Ischemia – steal phenomenon • Hydrocephalus • CN V palsy

15. Treatment • Optimal to defer surgical resection 4 – 6 wks after initial hemorrhage and clot evacuation • Not possible w/ Life threatening bleed • 53 pf-AVMs  15 emergent operation, AVM removed at time of evaluation in all (Sampson 2004) • Preoperative Embolization recommended • Occlude small feeders difficult to locate surgically • Caution occluding large vessels proximally • Great Benefit in Brainstem AVMs • Mortality 1.3% ; Severe-Mod AE 6.7%, 15.3% (Wikholm 1966)

16. Treatment • Radiosurgery GKRS • Small, unruptured, eloquence, elderly (Ciurea, 2010) • Latency of obliteration after treatment  no abatement of risk in that time (Ciurea 2010) • GKRS  Obliteration: 63% 2y; 73% 3y - 95% stable neurologically (Massager 2000) • Multimodal Therapy  recommended (Steinberg 2008) • SMG III-IV, mostly brainstem AVM • XRT alone  residual AVM on f/u

17. General Outcomes • Excellent to Good outcomes  71.0% - 82.1% • Poor morbid outcome  13.0% - 22% • Mortality  3.6% - 16.7% (Solomon 1986, Samson 1986; Symon 1995; Drake 1986; Steinberg 2008)

18. Outcome Associations • 12 pf-AVM w/ hemorrhage (Yilmaz 2011) • Worse w/ initial mRS, SMG grade, hematoma size • 59 pf-AVM w/ hemorrhage (van Loon 1993) • Worse w/ degree of 4th V compression, GCS • 98 pf-AVM • 61/98 (62.2%) w/ Hemorrhage (da Costa 2009) • Worse w/ presence of AA, initial mRS, # of treatments • 48 pf-AVM SMG III-IV (Steinberg 2008) • 37/48 (77.1%) w/ Hemorrhage; mean f/u 4.8y • Multimodal therapy >> XRT alone

19. Acknowledgments • CP&S • Dr. Jeffrey Bruce • Dr. Donald Quest • SD Andrew Chan • SD Brian Gill • MGH • Dr. William Butler • Dr. Patrick Codd • Dr. Chris Stapelton • Dr. Peter Fecci

20. NOTES BELOW HERE

21. Posterior Fossa AVMs • da Costa 2009 • 106 / 678 (15.6%) • 72.4% Cerebellar / 21.5% Brainstem • Cooperative Study of Intracranial Aneurysms and SAH (Perret 1966) • 32/453 7% • Drake 1986 • 116/600 20% • Vermian most common (Sampson 2004) • Arterial Input  distal SCA & distal PICA b/l • Large or involving 4th V  deep AICA feeders • Venous Drainage  Superiorly to Galenic System

22. Hemorrhage in PF-AVMs • Brugge, 2010 • 61/98 (62.3%) presented with Intracranial hemorrhage • Hemorrhage  reduced mRS at presentation (p=0.0229) though not final mRS (p=0.41) • AA, poor initial mRS, treatment  reduced final mRS • 52 f/u imaging  • 48.9% completelly obliterated • 13.4% smaller but patent nidus • 9.6% uchanged • 10/61 hemorrhaged in f/u 4.1% risk/year • No difference in treated vs. untreated