Clinical Pearl Series Edited from Yale-G First Aid: Crush USMLE Step 2CK & Step 3 by Yale Gong, MD, Sr. Medical Advisor at www.medicine.net (Copyrighted)
Traumatic brain injury (TBI)
It’s a common complex injury including closed, penetrating, and blast-induced injuries, with primary and secondary injury phases. TBI is a major cause of daily death and disability among civilians and military personnel with a huge cost in most countries. An initial diagnostic CT scan after a head trauma is always required.
Concussion
It can be defined as trauma-induced brain dysfunction without structural injury on standard neuroimaging. It is considered a mild form of TBI, accounting for 80% of TBI. Most patients may or may not have altered mental status; have no focal neurologic deficits; have normal CT scan results and good prognosis with expectant therapy.
Contusion
It refers to head injury that causes bruise, bleeding, and swelling of the skin mostly. A focal neurologic deficit may only exist occasionally. A CT scan may only show ecchymoses. Apply pressure to the wound with sterile gauze to treat.
Penetrating head trauma
Symptoms and CT scan results vary. It generally requires surgical repair of the damage.
Open fracture
It requires wound closure. A depressed fracture is treated in the operating room. Potential TBI may need further diagnosis and treatment.
Linear skull fracture
It needs observation only if it’s closed fracture(s) without overlying wound; otherwise it may require complex treatment.
Skull base fracture
Signs include raccoon eyes, rhinorrhea, and otorrhea or ecchymosis behind the ear. Initial cervical spine x-rays or CT scan is necessary, especially with a prior history. The treatment guideline is expectant therapy. Antibiotic use is not suggested.
Causes of neurologic damage and deficits from trauma
(1) The initial blow;
(2) The subsequent hematoma that displaces the midline structures;
(3) Secondarily increased ICP (intracranial pressure).
Diagnostic and therapeutic guidelines for head trauma and TBI
(1) It first requires a CT scan (without contrast) to look for intracranial hematomas. If CT scans and neurologic signs are negative within 24 hours, the patient can be watched closely by a family member at home during the next 24 hours to make sure no coma occurs again (highly important to save life!). A MRI is usually indicated for patients with symptoms but negative CT results for accurate diagnosis of TBI. Note that prior to lumbar puncture, always check bilateral papilledema that indicates elevated ICP. Unilateral papilledema may suggest a disease in the eye itself, such as an optic nerve glioma.
(2) Glial fibrillary acidic protein (GFAP), neurofilaments (NF), cathepsin B, and ubiquitin C-terminal hydrolase L1 (UCH-L1) are new blood biomarkers (proteins) of neurotrauma or degeneration and TBI to further help clinical diagnosis and treatment.
(3) Acute treatment depends on situations. Hypothermia and hyperbaric oxygen therapy may help reduce secondary brain injury. Medication treatment can prevent or minimize prolonged bleeding or the increase in ICP. Combined treatment of progesterone plus vitamin D3 and B3 +/- Mg-sulfide +/- nimodipine shows neuroprotective effects and better symptoms/outcome with severe TBI compared to monotherapy.
(4) Surgery may be necessary to relieve secondary hematoma.
Cerebrovascular Diseases (Stroke)
Stroke is the acute onset of focal neurologic deficits resulting from disruption of cerebral circulation. It is generally classified into two major types: ischemic and hemorrhagic strokes. Approximately 80% of strokes are due to ischemic (thrombotic) cerebral infarction and 20 percent to brain hemorrhage.
Risk factors for peripheral vascular diseases are also for stroke, including old age, family history, hyperlipidemia, coronary artery disease (CAD), hypercoagulability, smoking, hypertension (HTN), diabetes (DM), alcohol and drug abuse, male gender, etc. Note that low levels of LDL can lower the risk of ischemic stroke but may increase the risk of hemorrhagic stroke.
General Diagnostic Guidelines for Strokes
Diagnosis is based on history, physical examination, and imaging. Head CT scan is the best (sensitive) diagnostic means for hemorrhagic stroke and MRI is the best for embolic (ischemic) stroke.
Best consideration for an immediate head CT scan—for any suspicious space-occupying lesion:
1. Focal neurologic deficits, with or without confusion;
2. Presentations of brain herniation or elevated intracranial pressure (ICP): headache, vomiting, changed pupils, papilledema, seizures, etc.
Ischemic Stroke
It is brain ischemia due to the four common causes:
(1) Arterial thrombosis (local blood clotting, No.1 cause);
(2) Arterial embolism (cardioembolism);
(3) Systemic hypoperfusion (shock);
(4) Venous thrombosis.
Deficits are mostly maximal at onset, but may also be “stuttering” sometimes. The brain generally gets up to 40% of systemic emboli. Large vessel stroke includes carotid, vertebral, etc. Small vessel stroke includes lacunar, intracranial thrombosis, etc.
Important features: Recurrent transient ischemic attacks (TIAs) in the same artery distribution suggest large vessel stenosis. TIAs in different artery distributions suggest embolism.
Hemorrhagic Stroke
It is brain hemorrhage and associated neurologic deficits due to intracerebral hemorrhage (ICH) or subarachnoid hemorrhage (SAH). Hypertension is the most common cause. Statistic incidence has been decreased due to stringent BP control practice. Hemorrhagic stroke is much less than ischemic stroke but much more life-thretening, and therefore in need of serious prevention (strict blood pressure control) and urgent care once happening. The duration of most brain hemorrhage is less than 24 hours. Usually there are focal neurologic deficits in the anterior circulation—ipsilateral sensory, motor, or visual deficits. Posterior circulation deficits (vertebrobasilar) may appear as vertigo, diplopia, and dysarthria, etc.
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