Neuro-Ophthalmic Manifestations of Post-Concussion Syndrome
Neuro-ophthalmic manifestations of post-concussion syndrome
Post-concussion syndrome (PCS) is a constellation of symptoms and/or signs that commonly follow traumatic brain injury (TBI). Typically PCS/TBI occurs when an external force causes direct or indirect injury to the brain. PCS can occur after TBI of any severity. Although non-specific symptoms of headache, dizziness, poor concentration, poor memory and mood swings are common in PCS, neuro-ophthalmic symptoms and signs may be the presenting or predominant complaints. This article will discuss the neuro-ophthalmic consequences of TBI and PCS.
TBI can occur at any age. Accidental, occupational, and degenerative risk factors may increase the age specific risk in children, young adults, and the elderly. In 2018, one estimate suggested that non-fatal TBI accounts for 235,000 hospitalizations and about 1.1 million emergency room visits annually in the United States. In children and young adults, the most common causes were falls and motor vehicle accidents, respectively. Of patients with non-fatal TBI, 60-70% complained of visual symptoms related to PCS.
Risk factors for TBI include age > 75 years, < 4 years, or between 15-24 years, substance abuse, cognitive or psychiatric disorders, low socio-economic status, and participation in contact sports.
TBI usually occurs due to acceleration-deceleration injury. When the cranial vault is subjected to an outside force inducing abrupt changes in velocity, the brain moves internally and impact the cranial walls. This can lead to injuries ranging from mild (concussion) to severe (diffuse axonal injury). Neuroimaging may confirm extra-axial (e.g. epidural hematoma, sub-arachnoid hemorrhage), intra-axial (e.g., parenchymal bleed), focal or diffuse intracranial pathology but often the neuroimaging studies are normal in PCS. The neuro-ophthalmic manifestations of TBI depend on these structural factors as well the specific areas of the brain that are injured.
Persistent non-specific symptoms following TBI may include headache, dizziness, balance problems, photophobia, phonophobia, sleep problems, memory problems, poor reaction time, or changes in mood. The neuro-ophthalmic symptoms include blurry vision, diplopia, difficulty reading, or eye pain.
The most common neuro-ophthalmic findings following severe TBI include traumatic optic neuropathy, sequelae of increased intracranial pressure (e.g., postpapilledema optic atrophy) visual field defects (e.g., homonymous hemianopsia or cortical visual loss), or eye movement (e.g., ocular motor cranial neuropathy, nystagmus) which depend on the location of intracranial traumatic lesions. After mild TBI (concussion) however the most common visual disorders are convergence insufficiency (CI), accommodative insufficiency (AI), and mild saccadic dysfunction (SD).
Other deficits have also been noted in TBI including: color vision, stereopsis, pupillary function, smooth pursuit eye movements, critical flicker fusion frequency, vestibulo-ocular reflex, nystagmus, motion perception, visuo-spatial function, reading ability, and visual hallucinations.
A complete ophthalmologic and neurologic exam should be performed in symptomatic patients with TBI. Specific testing of visual fields, vergence, accommodation, and saccadic and pursuit eye movements is also recommended.
There is no cure for PCS or TBI related neuro-ophthalmic disease. The mainstay of treatment however for patients with persistent visual symptoms post-TBI is vision rehabilitation (e.g., oculomotor or convergence exercises). Vision rehabilitation typically combines in office visits with a vision specialist and home exercises, and often in conjunction with other types of TBI rehabilitation and outpatient therapy (e.g. vestibular therapy). It typically involves saccadic and pursuit activities such as Hart Chart, thumb rotations, rotating pegboard, and the Sanet Vision Integrator. Balance and head movements can also be performed for vestibular and vestibulo-ocular reflex stimulation. Patients also benefit from symptomatic treatment (e.g., tinted lenses for photophobia).
Symptoms from a PCS may resolve spontaneously or may persist for months or years. Resolution or improvement of visual symptoms is more likely with appropriate rehabilitation therapy.
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