Brown-Séquard syndrome is an incomplete spinal cord lesion characterized by a clinical picture reflecting hemisection injury of the spinal cord, often in the cervical cord region. (See Presentation.)
Patients with Brown-Séquard syndrome suffer from ipsilateral upper motor neuron paralysis and loss of proprioception, as well as contralateral loss of pain and temperature sensation. A zone of partial preservation or segmental ipsilateral lower motor neuron weakness and analgesia may be noted. Loss of ipsilateral autonomic function can result in Horner syndrome. (See Etiology, Presentation, and Workup.)
As an incomplete spinal cord syndrome, the clinical presentation of Brown-Séquard syndrome may range from mild to severe neurologic deficit. (See Presentation.)
The pure Brown-Séquard syndrome reflecting hemisection of the cord is not often observed. A clinical picture composed of fragments of the syndrome or of the hemisection syndrome plus additional symptoms and signs is more common. These less-pure forms of the disorder are often referred to as Brown-Séquard–plus syndrome.
Interruption of the lateral corticospinal tracts, the lateral spinal thalamic tract, and at times the posterior columns produces a picture of a spastic, weak leg with brisk reflexes and a strong leg with loss of pain and temperature sensation. Note that spasticity and hyperactive reflexes may not be present with an acute lesion.