EM@3AM: Brainstem Strokes

Answer: Brainstem stroke specifically in the pons resulting in locked in syndrome.

Risk factors:

• 10% of ischemic strokes occur in the brainstem²
• Risk factors for ischemic brainstem stroke³:
  • Atherosclerosis
  • Hypertension
  • Diabetes
  • Smoking
  • Atrial fibrillation
  • Hyperlipidemia
  • Ischemic heart disease
  • Embolism
  • Dissection
• Risk variables for hemorrhagic brainstem strokes ³:
  • Hypertension
  • Anticoagulant use
  • AV malformations
  • Amyloid angiopathy

Anatomy:⁴

Clinical presentation:

• Deficits depend on region affected⁵
• Localization
  • Step 1: Identify midbrain vs pons vs medulla involvement
    • “Rule of 4’s”⁵
      • Impaired CN I-IV = lesion above pons
      • Impaired CN V-VIII = lesion from the pons
      • Impaired IX-XII = lesion from the medulla
    • Step 2: Identify medial vs lateral involvement
      • 4 medial structures start with M⁵
        • Motor tract (corticospinal tract)
          • Deficit: contralateral weakness of limbs
        • Medial lemniscus (extension of dorsal columns)
          • Deficit: contralateral loss of vibration and proprioception of limbs
        • Medial longitudinal fasciculus
          • Deficit: ipsilateral internuclear ophthalmoplegia
        • Motor nuclei of CN III, IV, VI, XII
          • All divisible equally into 12
          • Deficit: respective CN motor dysfunction
      •  4 lateral structures start with S – s for side⁵
        • Spinocerebellar tract
          • Deficit: ipsilateral ataxia of the limbs
        • Spinothalamic tract
          • Deficit: contralateral loss of pain and temperature affecting the limbs
        • Sensory nucleus of CN V
          • Deficit: ipsilateral loss of pain and temperature affecting trigeminal distribution of face
        • Sympathetic tract
          • Deficit: ipsilateral Horner syndrome (classic triad- ptosis, miosis, anhidrosis)

Evaluation:

• Point-of-care glucose
  • Hypoglycemia can present with stroke-like symptoms
• NIHSS – National Institute of Health Stroke Scale used by Nebraska Mission: Lifeline Stroke⁶

• Non-contrast CT head, CTA head and neck or MRI⁷
  • CT preferred for speed and availability
    • Determines if there is hemorrhagic etiology
  • CTA head and neck is useful for identifying large-vessel occlusions (LVOs) which can be targets for mechanical thrombectomy
    • CT perfusion scan can also be used to help determine a penumbra
  • MRI is more sensitive for ischemic strokes
• Additional stroke workup: CBC, BMP, lipid panel, PT, PTT, hemoglobin A1C, EKG, hcg (if applicable)

Treatment:

• Stabilization of patient’s ABCs
• Normoglycemia
• Ischemic:
  • Thrombolytics if no contraindications
    • Contraindications for thrombolytics⁸

• • • ACEP 2015 Clinical Policy with B and C level recommendations for thrombolytics (tPA)⁹
    • Only ECASS-III (1995) and NINDS-II (2008) were RCTs that showed disability benefit, however some showed concern regarding imbalances in stroke severity and were re-analyzed¹⁰
      • NINDS: very small improvement in NIHSS – limited by small scale. No significant benefits were found
      • ECASS-III: No significant benefits were found
  • Permissive hypertension
  • Like cerebrovascular ischemic strokes, patients should be treated with dual anti-platelet therapy
  • If embolism at main vertebral or basilar artery, thrombectomy by a Neurointerventionalist may recommended
    • Small study in 2019 and 2020 showed no difference between thrombectomy vs medical treatment alone^11,12
      • More studies are needed to assess significance of thrombectomy in this patient population
• Hemorrhagic:
  • Reversal of anticoagulation
    • See link¹³ for more information
  • Control blood pressure¹⁴
    • Can use IV labetalol or nicardipine/clevidipine infusion
      • Blood pressure goals:
        • If ischemic and receiving thrombolysis
          • Prior to thrombolytics: <185/110
          • After thrombolytics: <180/105 for first 24 hours
        • If ischemic and NOT receiving thrombolysis allow permissive hypertension unless:
          • Systolic >220
          • Diastolic >120
          • Evidence of end organ damage
        • If hemorrhagic: systolic goal 140-180
          • AVOID hypotension and >10% decreases in blood pressure
  •  Surgery is controversial and NOT recommended. However, there is current trial underway to assess surgical management¹⁵

Disposition:

• Patients require close monitoring in intensive care with ischemic or hemorrhagic brainstem strokes
  • It is important to watch for worsening hemorrhage in closed space or if ischemic, the possibility of hemorrhagic conversion
    • Risk factors for hemorrhagic transformation (HT): advanced age, stroke severity (NIHSS), hypertension, hyperglycemia, poor collaterals, early infarction on brain imaging, low platelet count, use of antithrombotic drugs, and reperfusion therapy¹⁶
    • Alteplase and Tenecteplase have a similar 1% risk of symptomatic intracerebral hemorrhage and 5-6% of HT which includes >30% of infarcted tissue with marked mass effect^17,18

Pearls:

• Deficit depends on area affected:
  • Generally, if ipsilateral cranial nerve deficit with contralateral motor/sensory deficit – consider brainstem stroke syndrome
• Most common affected is:
  • Lateral medullary syndrome (Wallenburg syndrome) with vertigo, ipsilateral ataxia, ipsilateral sensory loss in face, dysphagia, dysphonia and dysarthria¹⁹
• Medical treatment is similar to cerebral cortex ischemic strokes – thrombolytics, dual anti-platelet therapy
  • No significant outcome improvement in thrombectomy vs medical management alone
  • If hemorrhagic – reversal of anticoagulation, surgical management NOT usually recommended
• Control blood pressure if receiving therapeutics, otherwise will tolerate permissive hypertension