Spinal cord injuries can profoundly affect an individual’s life, presenting a wide range of complexities depending on the nature and extent of the damage. Among the various types of spinal cord injuries, a hemicord lesion stands out as a specific condition where only one side of the spinal cord is affected. This distinct pattern of injury leads to a unique set of neurological symptoms that differentiate it from other spinal cord syndromes.
What is a Hemicord Lesion?
A hemicord lesion refers to damage that impacts only one lateral half of the spinal cord. The spinal cord acts as a major communication pathway, relaying sensory information from the body to the brain and transmitting motor commands from the brain to the muscles. When one side of this pathway is compromised, it disrupts the flow of these signals in specific ways. The classic clinical presentation associated with a hemicord lesion is known as Brown-Séquard syndrome, a neurological condition resulting from a hemisection, or partial severing, of the spinal cord.
This type of incomplete spinal cord injury primarily affects the cervical or thoracic regions of the spinal cord. Brown-Séquard syndrome accounts for a small percentage of traumatic spinal cord injuries.
Causes of Hemicord Lesions
Hemicord lesions can arise from a variety of factors, broadly categorized into traumatic and non-traumatic causes. Traumatic injuries are the most common reason, frequently including penetrating wounds like stab wounds or gunshot wounds. Blunt trauma and injuries sustained from motor vehicle accidents or falls can also lead to such a lesion.
Non-traumatic causes encompass a range of medical conditions. These include spinal cord tumors that compress one side of the cord, inflammatory conditions like transverse myelitis, and infections. Vascular issues, such as a spinal cord stroke or hemorrhage, can also cause a hemicord lesion. Additionally, conditions like multiple sclerosis can cause a hemicord lesion.
The Unique Pattern of Symptoms
The distinct neurological signs of a hemicord lesion are directly related to how sensory and motor pathways cross within the spinal cord and brain. Individuals with this injury exhibit a specific combination of deficits on both the same side (ipsilateral) and the opposite side (contralateral) of the body relative to the lesion. This predictable pattern is a hallmark of Brown-Séquard syndrome.
On the same side of the body as the spinal cord lesion, individuals experience a loss of motor function due to damage to the descending lateral corticospinal tracts. These tracts are responsible for voluntary movement and do not cross over until they reach the brainstem. Patients also lose proprioception and vibration sensation on the ipsilateral side, caused by damage to the ascending dorsal columns. These sensory pathways also travel up the spinal cord on the same side before crossing in the brainstem.
Conversely, on the opposite side of the body from the lesion, there is a loss of pain and temperature sensation. This occurs because the lateral spinothalamic tracts, which carry pain and temperature signals, cross over to the opposite side of the spinal cord shortly after entering. This unique contralateral sensory loss, coupled with ipsilateral motor and proprioceptive deficits, creates the characteristic clinical picture that helps identify a hemicord lesion.
Diagnosis and Treatment
Diagnosing a hemicord lesion, or Brown-Séquard syndrome, begins with a thorough clinical assessment and neurological examination. During this examination, healthcare professionals evaluate motor strength, sensation, and reflexes to pinpoint the affected areas and patterns of neurological deficits. This assessment helps determine the level and extent of the spinal cord injury.
Magnetic Resonance Imaging (MRI) is the preferred imaging modality to confirm the diagnosis and identify the underlying cause of the lesion. MRI can reveal the presence of unilateral pathology, such as a tumor, disc herniation, or evidence of trauma, which helps guide treatment decisions. The management approach for a hemicord lesion is highly individualized and depends on the specific cause of the injury.
Immediate medical management may include the use of corticosteroids. Surgical intervention might be necessary to address the underlying cause, such as removing a tumor or decompressing the spinal cord if there is compression. Regardless of the cause, rehabilitation, involving physical therapy and occupational therapy, plays a role in helping patients regain function and improve their quality of life.
Recovery and Prognosis
The recovery trajectory for individuals with hemicord lesions, or Brown-Séquard syndrome, can vary considerably based on the severity and cause of the injury. As an incomplete spinal cord injury, there is potential for functional improvement compared to complete spinal cord injuries. More than half of patients with Brown-Séquard syndrome experience good recovery, with the majority showing improvements in motor function.
The most notable improvements are observed within the first 9 to 12 months following the injury, with recovery continuing at a slower pace for up to two years. Dedicated rehabilitation, including physical and occupational therapy, is considered beneficial in maximizing recovery and improving overall outcomes. Many individuals with this syndrome can regain some ability to walk after rehabilitation.