Shaken Baby Syndrome (SBS) Ocular Findings with Legal Implications

Transcription

1 United States and Canadian Academy of Pathology 2007 Annual Meeting Shaken Baby Syndrome (SBS) Ocular Findings with Legal Implications J. Douglas Cameron, MD Professor of Ophthalmology Mayo Clinic School of Medicine Rochester, Minnesota Clinical Pathologic Correlations 1

2 Important Prologue Injury (disruption of form or function) is influenced by a large number of variables No two episodes of injury are exactly alike Non-Accidental injuries: Injuries are due to trauma intentionally inflected by another person The diagnosis of non-accidental injury to a child requires input form both clinicians and pathologists 2

3 Background Information (SBS) Definition Caffey (1946) Whiplash-shaken infant syndrome Lancon (1998) Child abuse Chase (1999) Abusive head injuries Case (2001) Shaken Baby Syndrome Keenan (2002) Inflicted childhood neuro trauma 3

4 The purpose of this talk Assist pathologists in identifying and reporting ocular findings in cases of suspected non-accidental injury Hemorrhage Retina Sclera Optic nerve Tissue displacement Vitreous Retina Optic nerve 4

5 Background Information (SBS) (Continued) Pathophysiology Not clearly understood Meta studies in progress New studies planned Transfer of kinetic energy Shaking Blunt force trauma The eye-wall (cornea + sclera) is intact Ocular Hemorrhage Tissue displacement 5

6 The Result of Pathophysiologic Mechanisms Hemorrhage Retina, location (subhyaloid, superficial, full thickness, subretinal) Retina, extent (focal posterior pole, focal peripapillary, confluent, extension to the ora serrata) Intrascleral (Circle of Zinn-Haller) Optic nerve (subdural, subarachnoid) 6

7 The Result of Pathophysiologic Mechanisms (continued) Tissue displacement Schisis of the retina (splitting) Retinal detachment (separation from the retinal pigment epithelium) Traction of the dural insertion in the sclera 7

8 Challenges to the Surgical Pathologist Interpreting ophthalmologist s notations Critical anatomy of the eye Autolysis and artifacts of the infant eye Acquiring the specimen Gross Dissection Macroscopic Characteristics Microscopic characteristics The diagnosis The Comment 8

9 Data from Clinicians Clinical Pathologic Correlations 9

10 Indirect Ophthalmoscopy 20D Lens Virtual, inverted, reversed image 10

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13 When in doubt; call the ophthalmologist 13

14 Superior Temporal Arcade Macula Ora Serrata Optic Disc Fovea Centralis Inferior Temporal Arcade The Posterior Pole 14

15 Superior Temporal Arcade Macula Ora Serrata Optic Disc Fovea Centralis Inferior Temporal Arcade The Posterior Pole 15

16 Interpreting the ophthalmologist s notations VA = visual acuity FF = fix and follow an object CF = count fingers Pictures = images of common objects EXT = external examination SLT = slit lamp examination PLE = pen light examination Indirect ophthalmoscopy = basic tool 16

17 Indirect Ophthalmoscopy (IO) Most common bedside evaluation Viewing an aerial virtual image Requires dilation of pupil (mydriacyl, neosynephrine) SD: Scleral depression: external pressure to bring the peripheral retina into view Clear media = retina clearly visible VH = vitreous hemorrhage Retinal hemorrhage 17

18 Data From Pathologists Clinical Pathologic Correlations 18

19 Retinal Hemorrhage NFL = nerve fiber layer Posterior pole: posterior hemisphere of the eye Peripapillary: around the optic nerve Macular: between the superior and inferior temporal arcade of vessels Peripheral: outside of the macula To ora: to the most peripheral retina 19

20 Essential Anatomy of the Eye Clinical Pathologic Correlations 20

21 P.O. = Pupil- Optic Nerve Section 21

22 Calottes = caps Intraretinal Hemorrhage Peripheral artifact Lange s s fold 22

23 Macula Artifact Optic Disc Scleral Surface 23

24 Morphology unique to children Immature anterior chamber angle Flat contour of the lens Posterior umbilication of the lens (fixation) Delicate, elongated ciliary processes Folding of the peripheral retina (Lange s fold) (fixation) 24

25 Epithelial irregularity = post mortem Drying artifact Immature anterior chamber angle Flattened profile of the crystalline lens 25

26 Autopsy Specimen Artifact not cataract Infant 26

27 The Immature Eye Posterior umbilication of the lens; Fixation artifact Primary Vitreous Persistent Hyaloid Vessels Tunica Vasculosa Lentis 27

28 Lange s Fold (fixation artifact) Vitreous Base Under age 3 years Identifies the junction of the retina and the ciliary body = Ora Serrata 28

29 Retina Transparent, cellular No extracellular space (necessary for transparency) Poorly supported architecture (Mueller cells) Regions Retinal blood supply 29

30 Basic Systems of the Retina Transmission Computation Reception No extracellular space --- Hemorrhage = destruction 30

31 Temporal Raphe Capillary Free Zone 31

32 Vascular System of the Retina Defined vascular channels inner half Parallels route of nerve fiber layer Dominant superior, inferior temporal arcades Avascular periphery Capillary-free zone 32

33 Blood Supply of the Retina Central retinal artery; end artery, no collateral vessels Located in the superficial retina, anterior 50% (no vessels in the external retina) The central macula is avascular (capillary-free zone) Separated from vitreous by the internal limiting membrane Density of circulation is proportional to the thickness of the retina Ora = thin Peripapillary = thick 33

34 Periphery of the Retina Avascular Few functional photoreceptors Nutrition from the choriocapillaris Microcystoid spaces 34

35 Retina Vitreous Base Ciliary Body Ora Serrata Sclera 35

36 Regions of the Retina Ora serrata: termination of the peripheral retina Macula (foveola centralis); temporal to the optic disc, most sensitive portion of the retina (best visual acuity) Peripapillary: region around the optic disc, thickest portion of the retina 36

37 Vitreous Transparent, acellular 80% volume of the eye 4 cc 4 grams Extracellular materials Type II collagen Hyaluronic acid (proteoglycan) Water 37

38 Vitreous A scaffolding structure Function complete at age 3 years Shrinks throughout live Origin of floaters 38

39 Regions of the Vitreous Base Weiggert s ligament Potential space of Berger Adhesions Optic cup Parafovea Blood vessels Lattice degeneration 39

40 Vitreous (continued) Degenerates after age 3 (floaters) Strong attachment: vitreous base at ora Relative attachments Peripapillary retina (optic disc) Perimacular retina (near fovea) Along the course of retinal blood vessels 40

41 Optic Nerve Meninges Dura: inserts into sclera Arachnoid: contiguous with the CNS Pia: distributes blood to the optic nerve axons Optic disc blood supply: Circle of Zinn- Haller Optic nerve blood supply: arachnoid Retina blood supply: central retinal artery 41

42 Central Retinal Artery and Vein 42

43 Short posterior ciliary arteries Branches of the ophthalmic artery Supply tissues of the optic disc End arteries 43

44 Cross Section of the Optic Nerve 12 mm posterior to the Sclera 44

45 Dura Arachnoid Pial septa defining Axonal columns Route of the Blood Supply 45

46 Orbit Orbital bones : usually intact Orbital soft tissues: usually no hemorrhage or disruption Preseptal soft tissues (eyelids) usually no hemorrhage or disruption 46

47 Autolysis and Artifacts Mechanical disruption or displacement of the lens during sectioning Detachment of the retina Degeneration of the photoreceptor outer segments Mechanical disruption of the neurosensory retina Incomplete or off-axial sections Pupil Optic disc 47

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49 Autolytic Separation of Vireo-retinal retinal Junction Autolytic Degeneration of Photoreceptor Outer Segments 49

50 Retinal Artifacts Detachment No subretinal material Amputation of RPE microvilli Sharp contours of retinal separation 50

51 Acquiring the Specimen Parsons, M. and R. Start (2001). "ACP Best Practice No 164: Necropsy techniques in ophthalmic pathology." Journal of Clinical Pathology 54: Anterior more direct Trans frontal more control (adequate optic nerve) Do not open the eye or penetrate the sclera before immersion fixation All important diagnostic information is within 2 mm of the external surface of the eye The sclera is not a barrier to the diffusion of formalin Opening the eye before fixation may result in loss of diagnostic information 51

52 Protocols Gross Dissection Traditional anterior-posterior Pupil Optic nerve Horizontal includes macula Equatorial section Simulates clinical findings Requires secondary sectioning Obtain a cross section of the optic nerve Photograph positive and negative findings 52

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56 Macroscopic Characteristics Few if any external signs of trauma Note color of sclera Important finding in osteogenesis imperfecta Indicates relative thickness of sclera Sclera may be thin in premature infants 56

57 Blue White Osteogenesis Imperfecta 57

58 Macroscopic (continued) Retina Retinal hemorrhage Location Extent Peripapillary Confluent Extension to the ora Tissue disturbance Elevation of the macula Retinal detachment 58

59 Peripapillary hemorrhage Ora Serrata Macular Traction Detachment Photograph for Files 59

60 Macroscopic (continued) Optic nerve Normal cross sectional diameter of myelinated nerve = 3 mm Preservation of neural axis Subdural hemorrhage Subarachnoid hemorrhage Optic nerve atrophy Seen with prolonged survival Diminished axonal column Expansion of subdural space 60

61 Posterior Segment Vascular Anchoring Points 61

62 Microscopic Characteristics Few if any signs of disruption of the anterior eye Cataract, very infrequent Retinal hemorrhage Within the retina (intraretinal) Under the retina (subretinal) Internal to the retina (subhyaloid) Displacement of the internal limiting membrane True retinal detachment 62

63 Retina Hemorrhage 63

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70 Area of macular traction, disruption and hemorrhage 70

71 Thick ganglion cell layer 71

72 Subretinal hemorrhage = true retinal detachment 72

73 z 73

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75 a 75

76 Sclera Hemorrhage Optic nerve Axona Circle of Zinn-Haller 76

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78 Subarachnoid & Subdural Hemorrhage 78

79 The Role of Iron Stains Gilliland, M., R. Folberg, et al. (2005). "Age of retinal hemorrhages by iron detection: an animal model." The American Journal of Forensic Medicine and Pathology 26: 1-4. The accuracy of intraretinal hemosiderin as an indication of previous injury Hemosiderin detected within 2 days in intraretinal hemorrhage caused by central retinal vein occlusion Hemosiderin may be associated with organization of extravasated blood Absence of hemosiderin does not exclude prior retinal hemorrhage 79

80 The Diagnosis Eye, right, autopsy specimen: extensive intraretinal and subretinal hemorrhage extending to the ora, focal detachment of the macula, hemorrhage present in the region of Zinn-Haller, extensive subdural and subarachnoid optic nerve hemorrhage (please see comment) Eye, left, autopsy specimen: focal intraretinal hemorrhage posterior pole (please see comment) 80

81 The Comment The findings of the right and left eyes are consistent with non-accidental injury, however, this report should be considered in the overall context of all available historical information, clinical findings, and the remainder of the autopsy findings Other comments 81

82 Summary Points (SBS) 1. Input from both clinicians and pathologists is necessary 2. Findings: Hemorrhage, tissue displacement of ocular tissues 3. Report location and extent 4. Obtain a long section of optic nerve 5. Eyes should be fixed before sectioning 6. Hemosiderin staining correlates poorly with time intervals 82

83 United States and Canadian Academy of Pathology 2007 Annual Meeting Shaken Baby Syndrome (SBS) Ocular Findings with Legal Implications J. Douglas Cameron, MD Professor of Ophthalmology Mayo Clinic School of Medicine Rochester, Minnesota Clinical Pathologic Correlations 83

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