4.1 Stroke Vascular Syndromes & Acute Assessment

Stroke Vascular Syndromes & Acute Assessment

Acute ischemic stroke remains one of the primary diagnoses managed by physical medicine and rehabilitation (PM&R) specialists. Precise neuroanatomical localization based on clinical presentation allows physiatrists to anticipate functional deficits, formulate targeted rehabilitation plans, and direct secondary prevention strategies. Ischemic stroke syndromes are broadly divided into anterior circulation territories (Middle Cerebral Artery and Anterior Cerebral Artery) and posterior circulation territories (Posterior Cerebral Artery, vertebrobasilar branches, and penetrating brainstem perforators), alongside small-vessel lacunar syndromes.

Anterior Circulation Syndromes

Middle Cerebral Artery (MCA) Territory

The Middle Cerebral Artery (MCA) is the largest branch of the internal carotid artery and the most common site of ischemic stroke. It supplies the lateral surface of the frontal, parietal, and temporal lobes, as well as deep subcortical structures (via lenticulostriate branches).

• Motor and Sensory Manifestations: MCA territory strokes produce contralateral hemiparesis and hemisensory loss affecting the face and upper extremity significantly more than the lower extremity (arm/face > leg). This classic pattern reflects the cortical homunculus, where motor and sensory representations of the face and arm lie on the lateral cerebral convexity (supplied by the MCA), while the lower extremity representation lies medially (supplied by the ACA).
• Dominant Hemisphere (Left MCA) Deficits: Occlusion of the dominant MCA (typically left hemisphere) disrupts cortical language networks:
  • Broca Aphasia (Expressive / Non-Fluent Aphasia): Results from damage to the left inferior frontal gyrus (Brodmann areas 44 and 45). Patients exhibit non-fluent, labored, telegraphic speech with impaired repetition, but speech comprehension remains remarkably intact. Patients are typically aware of their deficit, leading to significant frustration.
  • Wernicke Aphasia (Receptive / Fluent Aphasia): Results from damage to the left posterior superior temporal gyrus (Brodmann area 22). Patients present with fluent, voluminous, but paraphasic and nonsensical speech ("word salad"), accompanied by severely impaired auditory and reading comprehension and impaired repetition. Patients are typically unaware of their comprehension deficit (anosognosia).
  • Global Aphasia: Stem occlusion of the proximal M1 segment causes extensive frontotemporal infarction, producing a severe combination of non-fluent speech, absent comprehension, and complete right hemiplegia.
• Nondominant Hemisphere (Right MCA) Deficits: Occlusion of the nondominant MCA affects parietal spatial processing networks:
  • Hemispatial Neglect (Visuospatial / Personal Neglect): Patients fail to perceive, respond to, or attend to stimuli presented in the extrapersonal or personal space contralateral to the lesion (most commonly left-sided spatial neglect following a right parietal lesion).
  • Anosognosia: Lack of awareness of one's own neurological deficits (e.g., denying hemiplegia).
  • Constructional and Dressing Apraxia: Inability to draw, block-design, or align clothing with body parts.

Anterior Cerebral Artery (ACA) Territory

The Anterior Cerebral Artery (ACA) supplies the medial aspect of the frontal and parietal lobes, including the primary motor and sensory strips representing the lower extremity, as well as the anterior corpus callosum and supplementary motor area.

• Motor and Sensory Deficits: ACA strokes characteristically present with contralateral hemiparesis and hemisensory loss affecting the lower extremity significantly more than the upper extremity and face (leg > arm/face).
• Frontal Lobe and Cognitive Features: ACA infarction produces distinct behavioral and executive alterations:
  • Abulia: A profound state of apathy, lack of initiative, motor impersistence, and poverty of spontaneous speech, stemming from frontostriatal disruption.
  • Urinary Incontinence: Caused by infarction of the medial frontal micturition center, leading to loss of voluntary bowel/bladder inhibition.
  • Frontal Release Signs: Re-emergence of primitive reflexes including grasp, snout, and sucking reflexes.
  • Gait Apraxia: Magnetic or apraxic gait where the patient struggles to initiate walking despite preserved leg strength when lying supine.

Posterior Circulation Syndromes

Posterior Cerebral Artery (PCA) Territory

The Posterior Cerebral Artery (PCA) supplies the occipital cortex, inferior and medial temporal lobes, thalamus, and splenium of the corpus callosum.

• Visual Field Deficits: The hallmark of PCA stroke is contralateral homonymous hemianopia. Crucially, this hemianopia typically exhibits macular sparing because the extreme occipital pole representing macular vision receives dual collateral blood supply from terminal branches of the MCA.
• Higher Cortical Visual Syndromes:
  • Alexia Without Agraphia (Pure Alexia): Patients lose the ability to read written language but retain the full ability to write spontaneously and to dictation. This classic disconnection syndrome occurs when a left PCA stroke destroys the left primary visual cortex and the splenium of the corpus callosum. Visual information received by the intact right occipital cortex cannot cross the splenium to reach the left language areas (Wernicke area).
  • Visual Agnosia and Prosopagnosia: Inability to recognize familiar objects or faces, stemming from bilateral ventral occipitotemporal (fusiform gyrus) lesions.
• Thalamic Syndromes: PCA perforating branches supply the ventral posterolateral (VPL) and ventral posteromedial (VPM) thalamic nuclei. Dejerine-Roussy Syndrome (Post-Stroke Thalamic Pain) begins with transient contralateral sensory loss, followed weeks to months later by severe, agonizing, burning neuropathic pain provoked by light tactile stimuli (allodynia).

Lacunar Syndromes

Lacunar strokes result from lipohyalinosis and microatheroma occlusion of small penetrating arteries (100–400 μm diameter) such as lenticulostriate, thalamoperforating, and pontine perforator vessels. They produce small (<15 mm) subcortical focal infarcts.

• Pure Motor Hemiparesis: The most frequent lacunar syndrome (~33–50%), caused by an infarct in the posterior limb of the internal capsule or basis pontis. It presents with proportional weakness of the contralateral face, arm, and leg without sensory loss or cortical signs (no aphasia, no neglect).
• Pure Sensory Stroke: Infarction of the ventral posterolateral (VPL) nucleus of the thalamus. Presents with numbness, tingling, or sensory loss involving the contralateral face, arm, trunk, and leg without motor weakness.
• Clumsy Hand-Dysarthria Syndrome: Infarction of the paramedian pontine base or anterior limb/genu of the internal capsule. Characterized by severe dysarthria, facial weakness, dysphagia, and prominent upper extremity motor clumsiness out of proportion to weakness.
• Ataxic Hemiparesis: Infarction of the corona radiata, posterior limb of the internal capsule, or basis pontis. Characterized by a combination of cerebellar ataxia and weakness on the same side of the body.

Acute Stroke Assessment Tools

National Institutes of Health Stroke Scale (NIHSS)

The National Institutes of Health Stroke Scale (NIHSS) is a standardized 15-item quantitative assessment tool used to measure neurological deficit severity in acute stroke (score range 0–42).

• Key Categories: Evaluates level of consciousness, horizontal eye movement, visual fields, facial palsy, upper and lower extremity motor function, limb ataxia, sensory loss, best language (aphasia), dysarthria, and extinction/inattention (neglect).
• Severity Stratification:
  • 0: No stroke symptoms
  • 1–4: Mild stroke
  • 5–15: Moderate stroke
  • 16–20: Moderate-to-severe stroke
  • 21–42: Severe stroke (NIHSS ≥21 predicts high mortality and severe functional dependency).

Functional Independence Measure (FIM) & IRF-PAI Section GG

Functional recovery assessment guides inpatient rehabilitation facility (IRF) admission, goal setting, and discharge planning.

• Functional Independence Measure (FIM): Historically comprised 18 items (13 motor, 5 cognitive), rated on a 7-point ordinal scale ranging from 1 (Total Assistance - patient performs <25%) to 7 (Complete Independence). Total FIM scores range from 18 to 126.
• Inpatient Rehabilitation Facility Patient Assessment Instrument (IRF-PAI) Section GG: Modern CMS-mandated assessment tool replacing FIM. Measures functional performance across self-care and mobility items using a 6-point Function Scale:
  • 6: Independent
  • 5: Setup or clean-up assistance
  • 4: Supervision or touching assistance
  • 3: Partial/moderate assistance (helper does <50% of effort)
  • 2: Substantial/maximal assistance (helper does 50–99% of effort)
  • 1: Dependent (helper does 100% of effort)