What is the cause of a neurological deficit in the posterior limb of the internal capsule?

From the Guidelines

A neurological deficit in the posterior limb of the internal capsule is typically caused by intracerebral hemorrhage (ICH) or ischemic stroke, with ICH involving this location tend to have poorer outcomes compared to other locations. The posterior limb of the internal capsule is a critical region for motor function, and damage to this area can result in significant neurological deficits, including contralateral hemiparesis (weakness on the opposite side of the body) due to damage to the corticospinal tract fibers that pass through this region 1. Some key points to consider in the management of a neurological deficit in the posterior limb of the internal capsule include:

• The site of the hemorrhage or infarct has a clear impact on survival and functional outcome, with infratentorial location predicting a higher likelihood of death 1
• Prognosis varies according to deep and lobar location of supratentorial ICH, with ICH involving the posterior limb of internal capsule or thalamus tend to have poorer outcomes compared to other locations 1
• Treatment depends on the underlying cause, with ischemic stroke being the most common, and may involve intravenous thrombolysis, mechanical thrombectomy, antiplatelet therapy, statins, and blood pressure control
• Rehabilitation is crucial and should begin as early as possible, including physical therapy, occupational therapy, and speech therapy if needed The posterior limb contains important motor fibers, and damage occurs because this region receives blood supply primarily from the lenticulostriate branches of the middle cerebral artery, making it vulnerable to small vessel disease and embolic events 1. Recovery potential varies based on the extent of damage, timing of intervention, and individual factors, and early intervention and rehabilitation are critical to optimizing outcomes.

From the Research

Neurological Deficit in the Posterior Limb of the Internal Capsule

The cause of a neurological deficit in the posterior limb of the internal capsule can be attributed to various factors, including:

• Stroke or lacunar infarction, as evidenced by a study published in 2009 2, which reported a patient with dysnomia, ataxia, choreoathetosis, sensory impairment, and severe gait imbalance resulting from an isolated left lentiform nucleus-posterior limb of internal capsule lacunar stroke.
• Damage to the posterior limb of the internal capsule can also lead to proprioceptive impairments, as reported in a 2014 case series 3, which found that lesions in this area were associated with position sense and kinesthesia impairments.
• Additionally, central poststroke neuropathic pain and spasticity affecting the lower limb can be caused by damage to the posterior limb of the internal capsule, as suggested by a 2020 case series 4, which found that deep brain stimulation of this area can provide long-term pain relief and reduction in spasticity.

Associated Deficits

The neurological deficit in the posterior limb of the internal capsule can be associated with various deficits, including:

• Motor function impairments, as reported in a 2021 study 5, which found that higher fractional anisotropy values of the posterior limb of the internal capsule were associated with better recovery of upper limb function.
• Sensory impairments, as reported in the 2009 study 2, which found that the patient had sensory impairment and severe gait imbalance.
• Pain and spasticity, as reported in the 2020 case series 4, which found that deep brain stimulation of the posterior limb of the internal capsule can provide long-term pain relief and reduction in spasticity.

Treatment Options

Treatment options for neurological deficits in the posterior limb of the internal capsule include:

• Deep brain stimulation, as reported in the 2020 case series 4, which found that this procedure can provide long-term pain relief and reduction in spasticity.
• Chronic stimulation of the internal capsule, as reported in a 2008 case report 6, which found that this procedure can ameliorate pain and motor symptoms in patients with stroke.