# modified Brain Injury Guidelines (mBIG)

modified Brain Injury Guidelines (mBIG)

Status: LIVE
Price: $0.005 USDC
`GET /api/calc/mbig`
HTML: https://magentlab.com/docs/mbig
Markdown: https://magentlab.com/docs/mbig.md

Not a medical device. Not a diagnosis, dose, or listing recommendation.

## What it computes

Apply the Khan 2020 modified Brain Injury Guidelines and return mBIG tier 1, 2, or 3 from caller-assigned GCS, neurologic findings, medications, ethanol, skull fracture, and hematoma sizes.

## When to use

When an agent already has caller-assigned mild-TBI findings and CT hematoma sizes for an adult with traumatic ICH and needs the 2020 mBIG tier, not original Joseph 2014 BIG, not PECARN, and not Canadian CT Head.

## When not to use

- Not a medical device. Not a diagnosis. Not a neurosurgical plan or observation-order.
- Khan 2020 is for adults with mild TBI and traumatic ICH. magent does not read CT, measure hematoma thickness, assay ethanol, or compute GCS. All inputs are caller-assigned.
- This is the 2020 modified Brain Injury Guidelines, not original Joseph 2014 BIG. Any EDH is mBIG 3. Anticoagulant or antiplatelet excluding aspirin alone is mBIG 3; aspirin monotherapy is not scored as mBIG 3 on this API.
- Discharge requiring GCS 15 and published observation hours are not returned. Neurologic deterioration is not scored here.

## Formula

```
first-match worst-wins mBIG 3 then 2 then 1 (Khan 2020 modified criteria): mBIG 3 if GCS <= 12 or focal_neuro_or_pupillary_abnormality or ac_ap_excluding_aspirin or displaced skull fracture or sdh_mm >= 8 or iph_mm >= 8 or multiple_iph or sah scattered or sah_mm > 3 or any EDH or IVH; else mBIG 2 if etoh_gt_80 or nondisplaced skull fracture or sdh_mm >= 4 or iph_mm >= 4 or sah localized or sah_mm >= 1; else mBIG 1
```

## Citation

[Multicenter assessment of the Brain Injury Guidelines and a proposal of guideline modifications](https://doi.org/10.1136/tsaco-2020-000483)
Khan AD, Elseth AJ, Brosius JA, et al.
Trauma Surg Acute Care Open. 2020;5(1):e000483
DOI: [10.1136/tsaco-2020-000483](https://doi.org/10.1136/tsaco-2020-000483)

## Worked example

### GCS 15, SDH 3 mm, SAH none/trace is mBIG 1

Given: `ac_ap_excluding_aspirin=false, edh=false, etoh_gt_80=false, focal_neuro_or_pupillary_abnormality=false, gcs=15, iph_mm=0, ivh=false, multiple_iph=false, sah_mm=0, sah_pattern=none_or_trace, sdh_mm=3, skull_fracture=none`

1. No mBIG 3 feature: GCS 15, no focal or pupillary abnormality, no AC/AP excluding aspirin, skull fracture none, SDH 3 mm < 8, IPH 0, SAH none_or_trace and 0 mm, no EDH, no IVH
2. No mBIG 2 feature: EtOH not >80, no nondisplaced fracture, SDH 3 mm < 4, IPH 0, SAH none_or_trace and <1 mm
3. mBIG 1


### SDH 5 mm is mBIG 2

Given: `ac_ap_excluding_aspirin=false, edh=false, etoh_gt_80=false, focal_neuro_or_pupillary_abnormality=false, gcs=15, iph_mm=0, ivh=false, multiple_iph=false, sah_mm=0, sah_pattern=none_or_trace, sdh_mm=5, skull_fracture=none`

1. SDH 5 mm is >=4 and <8 and no mBIG 3 feature is met
2. mBIG 2


### Any EDH is mBIG 3

Given: `ac_ap_excluding_aspirin=false, edh=true, etoh_gt_80=false, focal_neuro_or_pupillary_abnormality=false, gcs=15, iph_mm=0, ivh=false, multiple_iph=false, sah_mm=0, sah_pattern=none_or_trace, sdh_mm=3, skull_fracture=none`

1. Khan 2020 classifies any epidural hematoma as mBIG 3
2. mBIG 3


## Also searched as

- modified Brain Injury Guidelines
- mBIG 2020
- Khan mBIG
- modified BIG
- traumatic ICH guidelines
- mBIG 1 2 3
- mild TBI ICH stratification
- Brain Injury Guidelines modified

## Parameters

- `gcs` (integer, required): Caller-assigned Glasgow Coma Scale total, integer 3-15. Khan 2020 methods: GCS of 12 or less is an abnormal neurologic examination and is mBIG 3. magent does not compute eye, verbal, or motor GCS.
- `focal_neuro_or_pupillary_abnormality` (boolean, required): Focal neurologic deficit or abnormal pupillary findings as assigned by the caller (Khan 2020 abnormal neurologic examination). true or false. true is mBIG 3. magent does not examine the patient.
- `ac_ap_excluding_aspirin` (boolean, required): Anticoagulant or antiplatelet therapy excluding aspirin alone, as assigned by the caller. true or false. true is mBIG 3. Aspirin monotherapy is false. magent does not read a medication list.
- `etoh_gt_80` (boolean, required): Blood alcohol concentration >80 mg/dL as assigned by the caller (Khan 2020 intoxication definition, US legal driving limit). true or false. true excludes mBIG 1 (mBIG 2 unless a mBIG 3 feature is also met). magent does not assay ethanol.
- `skull_fracture` (string, required): Skull fracture as assigned by the caller from CT: none (mBIG 1 row), nondisplaced (mBIG 2), or displaced (mBIG 3). magent does not read CT.
- `sdh_mm` (number, required): Largest subdural hematoma thickness in millimetres as assigned by the caller (0-40). mBIG 1 if <4, mBIG 2 if >=4 and <8, mBIG 3 if >=8. magent does not measure SDH or read CT.
- `iph_mm` (number, required): Largest intraparenchymal hemorrhage size in millimetres as assigned by the caller (0-40). mBIG 1 if <4, mBIG 2 if >=4 and <8, mBIG 3 if >=8. Use 0 when no IPH. magent does not measure IPH or read CT.
- `multiple_iph` (boolean, required): Multiple intraparenchymal hemorrhages as assigned by the caller. true or false. true is mBIG 3. magent does not count lesions on CT.
- `sah_pattern` (string, required): Traumatic SAH pattern as assigned by the caller from Khan 2020 sulci/hemisphere definitions that replace original BIG trace/localized/scattered: none_or_trace (<=3 sulci and <1 mm), localized (one hemisphere, >3 sulci, 1-3 mm), or scattered (bi-hemispheric or >3 mm). magent does not read CT.
- `sah_mm` (number, required): SAH thickness in millimetres as assigned by the caller (0-20). mBIG 1 if <1, mBIG 2 if 1-3, mBIG 3 if >3. Use 0 when none. Combined with sah_pattern; either scattered pattern or >3 mm is mBIG 3. magent does not measure SAH.
- `edh` (boolean, required): Any epidural hematoma as assigned by the caller. true or false. Any EDH is mBIG 3 (Khan 2020 safety modification versus original BIG size bands). magent does not read CT.
- `ivh` (boolean, required): Intraventricular hemorrhage as assigned by the caller. true or false. true is mBIG 3. magent does not read CT.

## Bulk (POST)

POST the same path with a JSON items array. The first item is the GET unit; each additional item is $0.002. Invalid items return HTTP 400 before settlement.

Method: `POST /api/calc/mbig`
Max items: 25
Price: unit_amount + extra_item_amount * (n - 1) (unit 5000 atomic, extra 2000 atomic)
Status: PREVIEW

- 1 to 25 items. Each item uses the same keys as the GET query parameters.
- POST of 1 item costs the same as GET. Lists longer than 25: chunk into multiple POSTs. Extra items still execute; do not pad dummy rows.
- The first invalid item fails the whole request (index in the 400 JSON). You are not charged.
- HTTP 200 is {count, path, items}. Each items[i] is the GET 200 body for that row.
- Catalog misses (empty matches, found=false) stay paid 200s inside that slot.
- x402 resource URL is this path plus n and body_sha256. Browsers that prefer text/html get the same paywall as GET; Pay retries POST with the same items.

Example request:

```json
{
  "items": [
    {
      "ac_ap_excluding_aspirin": "false",
      "edh": "false",
      "etoh_gt_80": "false",
      "focal_neuro_or_pupillary_abnormality": "false",
      "gcs": "15",
      "iph_mm": "0",
      "ivh": "false",
      "multiple_iph": "false",
      "sah_mm": "0",
      "sah_pattern": "none_or_trace",
      "sdh_mm": "3",
      "skull_fracture": "none"
    },
    {
      "ac_ap_excluding_aspirin": "false",
      "edh": "false",
      "etoh_gt_80": "false",
      "focal_neuro_or_pupillary_abnormality": "false",
      "gcs": "15",
      "iph_mm": "0",
      "ivh": "false",
      "multiple_iph": "false",
      "sah_mm": "0",
      "sah_pattern": "none_or_trace",
      "sdh_mm": "3",
      "skull_fracture": "none"
    }
  ]
}
```

Human paywall (two-item fixture): https://api.magentlab.com/paywall/bulk/mbig

Example 200:

```json
{
  "count": 2,
  "path": "/api/calc/mbig",
  "items": [
    {
      "disclaimer": "Not a medical device. Deterministic published-formula or published-code output for autonomous agents. A licensed clinician remains responsible for patient care and billing submissions.",
      "citation": {
        "authors": "Khan AD, Elseth AJ, Brosius JA, et al.",
        "doi": "10.1136/tsaco-2020-000483",
        "id": "khan-2020",
        "pmid": "32537518",
        "source": "Trauma Surg Acute Care Open. 2020;5(1):e000483",
        "title": "Multicenter assessment of the Brain Injury Guidelines and a proposal of guideline modifications"
      },
      "formula": "mbig",
      "formula_expression": "first-match worst-wins mBIG 3 then 2 then 1 (Khan 2020 modified criteria): mBIG 3 if GCS <= 12 or focal_neuro_or_pupillary_abnormality or ac_ap_excluding_aspirin or displaced skull fracture or sdh_mm >= 8 or iph_mm >= 8 or multiple_iph or sah scattered or sah_mm > 3 or any EDH or IVH; else mBIG 2 if etoh_gt_80 or nondisplaced skull fracture or sdh_mm >= 4 or iph_mm >= 4 or sah localized or sah_mm >= 1; else mBIG 1",
      "criteria": [
        {
          "value": 15,
          "factor": "gcs_le_12",
          "met": false
        },
        {
          "factor": "focal_neuro_or_pupillary_abnormality",
          "met": false
        },
        {
          "factor": "ac_ap_excluding_aspirin",
          "met": false
        },
        {
          "factor": "etoh_gt_80",
          "met": false
        },
        {
          "value": "none",
          "factor": "displaced_skull_fracture",
          "met": false
        },
        {
          "value": "none",
          "factor": "nondisplaced_skull_fracture",
          "met": false
        },
        {
          "value": 3.0,
          "factor": "sdh_ge_8",
          "met": false
        },
        {
          "value": 3.0,
          "factor": "sdh_ge_4",
          "met": false
        },
        {
          "value": 0.0,
          "factor": "iph_ge_8",
          "met": false
        },
        {
          "value": 0.0,
          "factor": "iph_ge_4",
          "met": false
        },
        {
          "factor": "multiple_iph",
          "met": false
        },
        {
          "value": "none_or_trace",
          "factor": "sah_scattered",
          "met": false
        },
        {
          "value": "none_or_trace",
          "factor": "sah_localized",
          "met": false
        },
        {
          "value": 0.0,
          "factor": "sah_mm_gt_3",
          "met": false
        },
        {
          "value": 0.0,
          "factor": "sah_mm_ge_1",
          "met": false
        },
        {
          "factor": "edh",
          "met": false
        },
        {
          "factor": "ivh",
          "met": false
        }
      ],
      "gcs": 15,
      "sah_pattern": "none_or_trace",
      "skull_fracture": "none",
      "iph_mm": 0.0,
      "sah_mm": 0.0,
      "sdh_mm": 3.0,
      "mbig_tier": 1
    },
    {
      "disclaimer": "Not a medical device. Deterministic published-formula or published-code output for autonomous agents. A licensed clinician remains responsible for patient care and billing submissions.",
      "citation": {
        "authors": "Khan AD, Elseth AJ, Brosius JA, et al.",
        "doi": "10.1136/tsaco-2020-000483",
        "id": "khan-2020",
        "pmid": "32537518",
        "source": "Trauma Surg Acute Care Open. 2020;5(1):e000483",
        "title": "Multicenter assessment of the Brain Injury Guidelines and a proposal of guideline modifications"
      },
      "formula": "mbig",
      "formula_expression": "first-match worst-wins mBIG 3 then 2 then 1 (Khan 2020 modified criteria): mBIG 3 if GCS <= 12 or focal_neuro_or_pupillary_abnormality or ac_ap_excluding_aspirin or displaced skull fracture or sdh_mm >= 8 or iph_mm >= 8 or multiple_iph or sah scattered or sah_mm > 3 or any EDH or IVH; else mBIG 2 if etoh_gt_80 or nondisplaced skull fracture or sdh_mm >= 4 or iph_mm >= 4 or sah localized or sah_mm >= 1; else mBIG 1",
      "criteria": [
        {
          "value": 15,
          "factor": "gcs_le_12",
          "met": false
        },
        {
          "factor": "focal_neuro_or_pupillary_abnormality",
          "met": false
        },
        {
          "factor": "ac_ap_excluding_aspirin",
          "met": false
        },
        {
          "factor": "etoh_gt_80",
          "met": false
        },
        {
          "value": "none",
          "factor": "displaced_skull_fracture",
          "met": false
        },
        {
          "value": "none",
          "factor": "nondisplaced_skull_fracture",
          "met": false
        },
        {
          "value": 3.0,
          "factor": "sdh_ge_8",
          "met": false
        },
        {
          "value": 3.0,
          "factor": "sdh_ge_4",
          "met": false
        },
        {
          "value": 0.0,
          "factor": "iph_ge_8",
          "met": false
        },
        {
          "value": 0.0,
          "factor": "iph_ge_4",
          "met": false
        },
        {
          "factor": "multiple_iph",
          "met": false
        },
        {
          "value": "none_or_trace",
          "factor": "sah_scattered",
          "met": false
        },
        {
          "value": "none_or_trace",
          "factor": "sah_localized",
          "met": false
        },
        {
          "value": 0.0,
          "factor": "sah_mm_gt_3",
          "met": false
        },
        {
          "value": 0.0,
          "factor": "sah_mm_ge_1",
          "met": false
        },
        {
          "factor": "edh",
          "met": false
        },
        {
          "factor": "ivh",
          "met": false
        }
      ],
      "gcs": 15,
      "sah_pattern": "none_or_trace",
      "skull_fracture": "none",
      "iph_mm": 0.0,
      "sah_mm": 0.0,
      "sdh_mm": 3.0,
      "mbig_tier": 1
    }
  ]
}
```

## Response fields

- `formula` (string): mbig
- `formula_expression` (string): Khan 2020 first-match worst-wins mBIG 3 then 2 then 1 rule
- `mbig_tier` (integer): 1, 2, or 3 from the modified criteria. Not a diagnosis or neurosurgical plan.
- `gcs` (integer): GCS total used (3-15)
- `sdh_mm` (number): SDH thickness in mm used
- `iph_mm` (number): IPH size in mm used
- `sah_mm` (number): SAH thickness in mm used
- `skull_fracture` (string): none, nondisplaced, or displaced as used
- `sah_pattern` (string): none_or_trace, localized, or scattered as used
- `criteria` (array): Per-factor rows with factor and met; GCS, SDH, IPH, SAH mm, skull_fracture, and sah_pattern rows include value
- `citation` (object): Khan 2020 TSACO citation
- `disclaimer` (string): Not-a-device notice

## Example JSON

Frozen fixture. Not a live lookup.

```json
{
  "disclaimer": "Not a medical device. Deterministic published-formula or published-code output for autonomous agents. A licensed clinician remains responsible for patient care and billing submissions.",
  "citation": {
    "authors": "Khan AD, Elseth AJ, Brosius JA, et al.",
    "doi": "10.1136/tsaco-2020-000483",
    "id": "khan-2020",
    "pmid": "32537518",
    "source": "Trauma Surg Acute Care Open. 2020;5(1):e000483",
    "title": "Multicenter assessment of the Brain Injury Guidelines and a proposal of guideline modifications"
  },
  "formula": "mbig",
  "formula_expression": "first-match worst-wins mBIG 3 then 2 then 1 (Khan 2020 modified criteria): mBIG 3 if GCS <= 12 or focal_neuro_or_pupillary_abnormality or ac_ap_excluding_aspirin or displaced skull fracture or sdh_mm >= 8 or iph_mm >= 8 or multiple_iph or sah scattered or sah_mm > 3 or any EDH or IVH; else mBIG 2 if etoh_gt_80 or nondisplaced skull fracture or sdh_mm >= 4 or iph_mm >= 4 or sah localized or sah_mm >= 1; else mBIG 1",
  "criteria": [
    {
      "value": 15,
      "factor": "gcs_le_12",
      "met": false
    },
    {
      "factor": "focal_neuro_or_pupillary_abnormality",
      "met": false
    },
    {
      "factor": "ac_ap_excluding_aspirin",
      "met": false
    },
    {
      "factor": "etoh_gt_80",
      "met": false
    },
    {
      "value": "none",
      "factor": "displaced_skull_fracture",
      "met": false
    },
    {
      "value": "none",
      "factor": "nondisplaced_skull_fracture",
      "met": false
    },
    {
      "value": 3.0,
      "factor": "sdh_ge_8",
      "met": false
    },
    {
      "value": 3.0,
      "factor": "sdh_ge_4",
      "met": false
    },
    {
      "value": 0.0,
      "factor": "iph_ge_8",
      "met": false
    },
    {
      "value": 0.0,
      "factor": "iph_ge_4",
      "met": false
    },
    {
      "factor": "multiple_iph",
      "met": false
    },
    {
      "value": "none_or_trace",
      "factor": "sah_scattered",
      "met": false
    },
    {
      "value": "none_or_trace",
      "factor": "sah_localized",
      "met": false
    },
    {
      "value": 0.0,
      "factor": "sah_mm_gt_3",
      "met": false
    },
    {
      "value": 0.0,
      "factor": "sah_mm_ge_1",
      "met": false
    },
    {
      "factor": "edh",
      "met": false
    },
    {
      "factor": "ivh",
      "met": false
    }
  ],
  "gcs": 15,
  "sah_pattern": "none_or_trace",
  "skull_fracture": "none",
  "iph_mm": 0.0,
  "sah_mm": 0.0,
  "sdh_mm": 3.0,
  "mbig_tier": 1
}
```

## Errors

- HTTP 400 `invalid_gcs_total`: gcs must be an integer from 3 to 15. Returned before settlement; you are not charged.
- HTTP 400 `invalid_sdh_mm`: sdh_mm must be a number from 0 to 40 (Khan 2020 mBIG subdural thickness mm). Returned before settlement; you are not charged.
- HTTP 400 `invalid_iph_mm`: iph_mm must be a number from 0 to 40 (Khan 2020 mBIG intraparenchymal hemorrhage mm). Returned before settlement; you are not charged.
- HTTP 400 `invalid_sah_mm`: sah_mm must be a number from 0 to 20 (Khan 2020 mBIG subarachnoid thickness mm). Returned before settlement; you are not charged.
- HTTP 400 `invalid_flag`: boolean clinical flags must be true or false Returned before settlement; you are not charged.
- HTTP 400 `invalid_items`: POST body must be a JSON object with only an items array Returned before settlement; you are not charged.
- HTTP 400 `invalid_item_count`: items must be an array of 1 to 25 objects Returned before settlement; you are not charged.
- HTTP 400 `invalid_item`: each items entry must be a JSON object Returned before settlement; you are not charged.

Shared HTTP 402 and 503: https://magentlab.com/docs/payments

## Related tools

- [PECARN pediatric head CT](https://magentlab.com/docs/pecarn-head) — Apply the Kuppermann 2009 PECARN prediction trees and return high, intermediate, or low risk of clinically important brain injury from caller-assigned findings after pediatric head trauma.
- [Canadian CT Head Rule](https://magentlab.com/docs/canadian-ct-head) — Apply the Stiell 2001 Canadian CT Head Rule and return whether CT is indicated from caller-assigned high-risk and medium-risk findings after minor blunt head injury.

## Payment

Unpaid requests return HTTP 402 even if query parameters or POST items are missing or invalid, so CDP and agents can index the path. After a PAYMENT-SIGNATURE, invalid params return HTTP 400 JSON before settlement. magent does not charge. Fix the params, then request a new 402 quote for that complete URL. Catalog misses (empty matches, found=false) are valid paid 200s.

- GET the tool with Accept: application/json (do not send Accept: text/html unless you want the human paywall).
- HTTP 402 means you have not paid. Decode the base64 PAYMENT-REQUIRED header. HTTP 503 is not a new quote.
- Sign accepts[0] (exact, EIP-3009) with validBefore = now + maxTimeoutSeconds (600 seconds), or accepts[1] (batch-settlement deposit/voucher) on product GET. Ping and POST {items} stay exact. Magent retries transient facilitator 429/5xx before answering.
- Retry the same URL with PAYMENT-SIGNATURE (base64 JSON of accepted and payload). Magent attaches canonical extensions.bazaar on CDP verify/settle; echoing 402 bazaar is optional.
- Success is HTTP 200 JSON plus PAYMENT-RESPONSE. exact settles before the tool. batch-settlement verifies (and deposit-settles) before the tool and commits the charge after HTTP 2xx. HTTP 503: retry the same PAYMENT-SIGNATURE. Mint a new exact nonce only after a new HTTP 402.

- offered `exact` on eip155:8453: Fixed-price USDC on Base. The buyer authorizes the advertised amount (EIP-3009). magent settles before the tool runs (paymentFlow upfront). extra.assetTransferMethod=eip3009 extra.paymentFlow=upfront.
- offered `batch-settlement` on eip155:8453: Payment-channel vouchers claimed later in batches. Exact stays accepts[0]. Same-path POST {items} is still exact. extra.assetTransferMethod=eip3009 extra.paymentFlow=authorization.

- not offered `upto`: Not offered. Usage-based: buyer authorizes a ceiling, seller settles the actual amount after work. Reserved for a future metered tool. Not for current calculators or code search.

Same-path POST {items} is still scheme exact: one EIP-3009 authorization for GET unit plus $0.002 per extra item. That is not x402 batch-settlement (payment channels / vouchers).

Shared HTTP 402 and 503 table: https://magentlab.com/docs/payments

Stdio MCP (one process per host): https://magentlab.com/docs/mcp

## Guarantees

- HTTP 402 is unpaid, including a missing query. After PAYMENT-SIGNATURE, invalid parameters return HTTP 400 before settlement. You are not charged. HTTP 402 never includes the tool JSON.
- exact: settlement finishes before the tool (paymentFlow upfront). batch-settlement: verify/deposit before the tool; chargedCumulativeAmount commits after HTTP 2xx. Uncertain or failed settlement fails closed (HTTP 503). Retry the same PAYMENT-SIGNATURE.
- HTTP 402 is unpaid only. Do not sign a second authorization because of a 503.
- Execution is timeout-bounded and concurrency-capped.
- Calculator inputs are stored encrypted for allowlisted operators (Magent Console). They are not in public logs, SSH lookups, catalog, or rollups. Request logs store path without query.