Head CT forHead CT forMild Traumatic Brain InjuriesMild Traumatic Brain Injuries

Michael Oh MS4Michael Oh MS4

RadiologyRadiology

March 2007March 2007

Mild Traumatic Brain Injury (MTBI)Mild Traumatic Brain Injury (MTBI)

Injury caused by blunt contact and/or Injury caused by blunt contact and/or acceleration/deceleration forcesacceleration/deceleration forcesAlso known as concussionAlso known as concussion AAN defines concussion as altered mental status +/- AAN defines concussion as altered mental status +/-

LOC due to traumaLOC due to trauma

Main criteriaMain criteria: Glasgow Coma Scale (GCS) score : Glasgow Coma Scale (GCS) score of 13-15of 13-15LOC <20min +/- brief retrograde amnesia (<1hr)LOC <20min +/- brief retrograde amnesia (<1hr)no focal neurological deficitsno focal neurological deficitsno intracranial complications (i.e. seizures)no intracranial complications (i.e. seizures)

Incidence of MTBIIncidence of MTBI

~1.4 million all traumatic brain injuries per year ~1.4 million all traumatic brain injuries per year in USin US ~75-95% are MTBIs ~75-95% are MTBIs (~1-1.3 million per year!!!)(~1-1.3 million per year!!!)

$56 billion / year cost for TBIs in US$56 billion / year cost for TBIs in US 44% due to MTBIs44% due to MTBIs

MVI (45%), falls (30%), occupational accidents MVI (45%), falls (30%), occupational accidents (10%), recreational accidents (10%), assaults (10%), recreational accidents (10%), assaults (5%).(5%).MTBI also very common in contact sportsMTBI also very common in contact sports 10% of college and 20% of high school 10% of college and 20% of high school

football players each seasonfootball players each season

Neuropathophysiology of MTBINeuropathophysiology of MTBI

Diffuse axonal injury (DAI)Diffuse axonal injury (DAI) Shear forces in brain caused by sudden decelerationShear forces in brain caused by sudden deceleration

Impairments in axonal transport, axonal swelling, Impairments in axonal transport, axonal swelling, Wallerian degeneration, and axonal transectionWallerian degeneration, and axonal transectionCortical contusions due to coup and contrecoup Cortical contusions due to coup and contrecoup injuriesinjuriesRelease of excitatory neurotransmitters (Ach, Release of excitatory neurotransmitters (Ach, glutamate, aspartate) generates free radicals glutamate, aspartate) generates free radicals and excitotoxicity, leading to secondary injuriesand excitotoxicity, leading to secondary injuries

Clinical FeaturesClinical Features

Confusion and amnesia +/- brief LOCConfusion and amnesia +/- brief LOC

Early symptoms (min to hrs): HA, Early symptoms (min to hrs): HA, dizziness, vertigo, N/Vdizziness, vertigo, N/V

Late symptoms (hrs to days): mood and Late symptoms (hrs to days): mood and cognitive disturbances, sensitivity to light cognitive disturbances, sensitivity to light and noise, sleep disturbancesand noise, sleep disturbances

Indications for further evaluationIndications for further evaluation

Impaired consciousness (GCS < 15)Impaired consciousness (GCS < 15)AmnesiaAmnesiaNeuro symptoms: HA, N/V, AMS, seizuresNeuro symptoms: HA, N/V, AMS, seizuresEvidence of skull fx: CSF leak, periorbital Evidence of skull fx: CSF leak, periorbital hematomahematomaEtOH or anticoagulationEtOH or anticoagulationMechanism of injury:Mechanism of injury: High energy injury (MVI, fall, etc.)High energy injury (MVI, fall, etc.) Possible penetrating injuryPossible penetrating injury Possible non-accidental injury (child abuse)Possible non-accidental injury (child abuse)

Poor social conditions: i.e. no supervision at homePoor social conditions: i.e. no supervision at home

MTBI can progress to more MTBI can progress to more serious Complicationsserious Complications

Intracranial complications: 6-21%Intracranial complications: 6-21%Neurosurgical intervention: Neurosurgical intervention: only 0.4-1%!!!only 0.4-1%!!!Brain contusionsBrain contusions Localized ischemia, edema, and mass effectLocalized ischemia, edema, and mass effect

HemorrhageHemorrhage Highly suspicious if neurological deterioration followsHighly suspicious if neurological deterioration follows Worsening HA, focal neurologic signs, confusion, and Worsening HA, focal neurologic signs, confusion, and

lethargy lethargy LOC or death. LOC or death. Intraparenchymal, subarachnoid, subdural, or epiduralIntraparenchymal, subarachnoid, subdural, or epidural

Both contusions and hemorrhage can cause Both contusions and hemorrhage can cause mass effect and brain herniations/deathmass effect and brain herniations/death

Indications for Neurosurgical Indications for Neurosurgical ConsultConsult

Bleed in Head CTBleed in Head CTPersisting coma (GCS < 8)Persisting coma (GCS < 8)Confusion > 4hrsConfusion > 4hrsDeterioration of consciousnessDeterioration of consciousnessFocal neurological signsFocal neurological signsSeizures without full recoverySeizures without full recoveryDepressed skull fxDepressed skull fxPenetrating injuryPenetrating injury

Evaluation of MTBIEvaluation of MTBI

First: medical evaluationFirst: medical evaluationSimple questions of orientation is insensitiveSimple questions of orientation is insensitiveStandardized Assessment of Concussion (SAC, Standardized Assessment of Concussion (SAC, McCrea et al.)McCrea et al.) Orientation (to time)Orientation (to time) Immediate memory (repeating words)Immediate memory (repeating words) Concentration (repeating string of numbers in reverse)Concentration (repeating string of numbers in reverse) Delayed recall (recall of words after 5 min)Delayed recall (recall of words after 5 min) Neurologic screening (neuro exam)Neurologic screening (neuro exam) Exertional maneuvers (sprint, sit-ups, push-ups, knee Exertional maneuvers (sprint, sit-ups, push-ups, knee

bends)bends)

NeuroimagingNeuroimaging

Imaging: Head CT is the gold standardImaging: Head CT is the gold standardMRI is more sensitive for axonal injuries, MRI is more sensitive for axonal injuries, but not always specific and do not but not always specific and do not correlate with TBI severity or outcome.correlate with TBI severity or outcome.Cost: MRI >>> CTCost: MRI >>> CTPlus all clinically important and Plus all clinically important and neurosurgical injuries are detected by CTneurosurgical injuries are detected by CTFunctional scans are not cost-effective Functional scans are not cost-effective and have not been standardizedand have not been standardized

Intraparenchymal HemorrhageIntraparenchymal Hemorrhage

Subarachnoid HemorrhageSubarachnoid Hemorrhage

Subdural Hemorrhage (acute)Subdural Hemorrhage (acute)

Epidural HemorrhageEpidural Hemorrhage

GCS is critical in determining GCS is critical in determining the need for Head CTthe need for Head CT

GCS < 8 requires intubation for airway GCS < 8 requires intubation for airway protection protection obtain Head CT obtain Head CT

GCS 9-12 is moderate TBI GCS 9-12 is moderate TBI obtain Head CT obtain Head CT

GCS 13-15 in mild TBI. Do we need to scan 1-GCS 13-15 in mild TBI. Do we need to scan 1-1.3 million heads per year??? No!!!1.3 million heads per year??? No!!! How often does head CT pick up abnormalities that How often does head CT pick up abnormalities that

require neurosurgical interventions?require neurosurgical interventions?

Head CT in MTBIHead CT in MTBI

GCS = 15 GCS = 15 5% abnormal CT 5% abnormal CT

GCS = 14 GCS = 14 20% abnormal CT 20% abnormal CT

GCS = 13 GCS = 13 30% abnormal CT 30% abnormal CT

However, only 1% all pts with MTBI (GCS 13-15) However, only 1% all pts with MTBI (GCS 13-15) have abnormalities on CT that require have abnormalities on CT that require neurosurgical interventionneurosurgical intervention

How to determine the need for How to determine the need for Head CTHead CT

Two clinical criteria have been proposed to Two clinical criteria have been proposed to help determine the need for Head CT in help determine the need for Head CT in MTBIMTBI Canadian CT Head Rule (CCHR: Stiell et al. Canadian CT Head Rule (CCHR: Stiell et al.

2001)2001) New Orleans Criteria (NOC: Haydel et al. New Orleans Criteria (NOC: Haydel et al.

2000)2000)

Canadian CT Head Rule (CCHR)Canadian CT Head Rule (CCHR)

Patient population: GCS 13-15, +LOC, no neuro deficits, Patient population: GCS 13-15, +LOC, no neuro deficits, no seizure, no anticoagulation, aged > 16no seizure, no anticoagulation, aged > 16Mandatory for head CT if any one:Mandatory for head CT if any one:

GCS < 15 at 2hrs postinjuryGCS < 15 at 2hrs postinjury Suspected skull fxSuspected skull fx Any signs of basilar skull fx: hemotympanum, raccoon eyes, Any signs of basilar skull fx: hemotympanum, raccoon eyes,

Battle’s sign, CSF leakBattle’s sign, CSF leak Vomiting (Vomiting (≥ ≥ 2)2) Aged Aged ≥ ≥ 6565

Head CT recommended, otherwise close clinical Head CT recommended, otherwise close clinical observationobservation

Retrograde amnesia >30minRetrograde amnesia >30min Dangerous mechanism (MVI, fall, etc.)Dangerous mechanism (MVI, fall, etc.)

Canadian CT Head Rule (CCHR)Canadian CT Head Rule (CCHR)

Sensitivity 98.4%Sensitivity 98.4%

Specificity 49.6%Specificity 49.6%

Potential reduction in number of Head CTs Potential reduction in number of Head CTs in ERs: in ERs: 46%!!!46%!!!

New Orleans Criteria (NOC)New Orleans Criteria (NOC)

GCS = 15, +LOC, no neuro deficit, aged >3yrsGCS = 15, +LOC, no neuro deficit, aged >3yrs

Indication for Head CT if any one:Indication for Head CT if any one: HAHA VomitingVomiting SeizureSeizure Intoxication or drug involvementIntoxication or drug involvement Short-term memory deficitShort-term memory deficit Aged >60yrsAged >60yrs Other visible injuries above clavicleOther visible injuries above clavicle

New Orleans Criteria (NOC)New Orleans Criteria (NOC)

Sensitivity 100%Sensitivity 100%

Specificity 24.5%Specificity 24.5%

Potential reduction in number of Head CTs Potential reduction in number of Head CTs in ERs: in ERs: 23% (vs. 46% in CCHR)23% (vs. 46% in CCHR)

Less specific compared to Canadian CT Less specific compared to Canadian CT Head Rule due to EtOH/drug criteriaHead Rule due to EtOH/drug criteria

CCHR vs. NOCCCHR vs. NOC

Stiell et al. JAMA (2005)Stiell et al. JAMA (2005) For patients with For patients with GCS = 15GCS = 15 Neurosurgical patients = 0.4%Neurosurgical patients = 0.4% CCHR and NOC have equivalent high sensitivities for CCHR and NOC have equivalent high sensitivities for

neurosurgical cases and clinically important brain neurosurgical cases and clinically important brain injury (100% for both)injury (100% for both)

Specificity for clinically important brain injurySpecificity for clinically important brain injuryCCHR (50.6%) > NOC (12.7%)CCHR (50.6%) > NOC (12.7%)

Specificity for neurosurgical casesSpecificity for neurosurgical casesCCHR (76.3%) > NOC (12.1%)CCHR (76.3%) > NOC (12.1%)

CCHR (52.1%) would result in lower CT rates CCHR (52.1%) would result in lower CT rates compared to NOC (88.0%)!!!compared to NOC (88.0%)!!!

CCHR vs. NOCCCHR vs. NOC

Smits et al. JAMA 2005Smits et al. JAMA 2005 For patients with For patients with GCS 13-15GCS 13-15 Neurosurgical patients = 0.5%Neurosurgical patients = 0.5% CCHR and NOC have equivalent high sensitivities for CCHR and NOC have equivalent high sensitivities for

neurosurgical cases (100% for both)neurosurgical cases (100% for both) NOC (97.7-99.4%) has higher sensitivity for clinically NOC (97.7-99.4%) has higher sensitivity for clinically

important brain injury than CCHR (83.4-87.2%)important brain injury than CCHR (83.4-87.2%) BUT…Specificity was very low for NOCBUT…Specificity was very low for NOC

CCHR (37.2-39.7%) > NOC (3.0-5.6%)CCHR (37.2-39.7%) > NOC (3.0-5.6%) CCHR would lower CT rates by 37.3% compared to CCHR would lower CT rates by 37.3% compared to

only 3.0% for NOC!!!only 3.0% for NOC!!! Thus, CCHR seems better compared to NOCThus, CCHR seems better compared to NOC

Further studies still required!Further studies still required!

Do we need 100% sensitivity on Head CT for Do we need 100% sensitivity on Head CT for clinically important brain injury that does not clinically important brain injury that does not require further interventions (neurosurgery)?require further interventions (neurosurgery)? Can some of these patients do well with observation Can some of these patients do well with observation

alone without the initial head CT?alone without the initial head CT?

Which group of patient would benefit from head Which group of patient would benefit from head CT for clinical follow-up, despite not requiring CT for clinical follow-up, despite not requiring neurosurgery?neurosurgery?

Which patients can be sent home rather than Which patients can be sent home rather than admitted or held in ER for observation?admitted or held in ER for observation?

ReferencesReferencesBorg et al. Diagnostic procedures in mild traumatic brain injury: results of Borg et al. Diagnostic procedures in mild traumatic brain injury: results of the WHO collaborating centre task force on mild traumatic brain injury. the WHO collaborating centre task force on mild traumatic brain injury. J J Rehabil MedRehabil Med (2004) 43 Suppl:61. (2004) 43 Suppl:61.Cushman et al. Practice management guidelines for the management of Cushman et al. Practice management guidelines for the management of mild traumatic brain injury: The EAST practice management guidelines work mild traumatic brain injury: The EAST practice management guidelines work group. (2001).group. (2001).Haydel et al. Indications for computed tomography in patients with minor Haydel et al. Indications for computed tomography in patients with minor head injury. head injury. N Engl J MedN Engl J Med (2000) 343:100. (2000) 343:100.McCrea et al. Standardized assessment of concussion in football players. McCrea et al. Standardized assessment of concussion in football players. NeurologyNeurology (1997) 48:586. (1997) 48:586.Smits et al. External validation of the Canadian CT Head Rule and the New Smits et al. External validation of the Canadian CT Head Rule and the New Orleans Criteria for CT scanning in patients with minor head injury. Orleans Criteria for CT scanning in patients with minor head injury. JAMAJAMA (2005) 294:1519.(2005) 294:1519.Stiell et al. The Canadian CT Head Rule for patients with minor head injury. Stiell et al. The Canadian CT Head Rule for patients with minor head injury. LancetLancet (2001) 357:1391. (2001) 357:1391.Stiell et al. Comparison of the Canadian CT Head Rule and the New Stiell et al. Comparison of the Canadian CT Head Rule and the New Orleans Criteria in patients with minor head injury. Orleans Criteria in patients with minor head injury. JAMAJAMA (2005) 294:1511. (2005) 294:1511.UpToDateUpToDate: Concussion and mild traumatic brain injury (2007).: Concussion and mild traumatic brain injury (2007).