Left Frontal Lobe Injury: Cognitive, Behavioral, and Motor Effects

The left frontal lobe governs language, executive function, and right-sided motor control. Injury effects depend on lesion location, size, and etiology (trauma, stroke, tumor, surgery).

Key Functional Domains Affected

1. Language (Dominant Hemisphere in ~95% of Right-Handers)

• Broca's area (BA 44/45): Expressive aphasia – non-fluent, effortful speech, preserved comprehension.
• Prefrontal language networks: Word-finding difficulty, reduced verbal fluency, impaired syntax.

2. Executive Dysfunction

• Planning, organization, working memory, decision-making, impulse control deficits.
• Perseveration, disinhibition, apathy, poor insight (anosognosia).

3. Memory

• Encoding/retrieval deficits for verbal material; prospective memory (remembering to do things) impaired.
• Often disproportionate to medial temporal lobe integrity.

4. Personality & Behavior

• Irritability, emotional lability, reduced empathy, social inappropriateness.
• Depression, anxiety common post-injury.

5. Motor Deficits

• Right hemiparesis/hemiplegia (primary motor cortex/premotor).
• Apraxia (impaired skilled movements) – especially buccofacial and limb-kinetic.
• Dysarthria, dysphagia if face/mouth area involved.

6. Seizure Risk

Frontal lobe epilepsy: brief, stereotyped, often nocturnal, with hypermotor or asymmetric tonic features.

Recovery & Rehabilitation

• Neuroplasticity greatest in first 3–6 months; continues years.
• Speech-language therapy (aphasia, apraxia of speech).
• Cognitive rehabilitation (compensatory strategies, metacognitive training).
• Physical/occupational therapy for motor recovery.
• Neuropsychiatric management (SSRIs, stimulants for apathy, behavioral plans).

Outcomes highly variable. Early, intensive, multidisciplinary rehab maximizes independence.