Ipsilateral weakness and loss of light touch and proprioception associated with a contralateral loss of pain and temperature sensation is characteristic of Brown-Sequard syndrome. The weakness in Brown-Sequard is ipsilateral to the lesion, so the answer is left cord hemisection.
This gentleman presents with the classic Brown-Sequard syndrome, which is most commonly caused by a partial cord transection from a traumatic cause such as a knife wound. The neurological findings in this condition are due to the long tract topography in the spinal cord. Pain and temperature sensation cross in the anterior white matter commissure of the spinal cord, so deficits in these areas would be contralateral to the lesion. The motor deficit is due to disruption of the corticospinal tracts, which have already crossed at the pyramidal decussation in the medulla. Similarly touch and proprioception are in the dorsal columns which remain uncrossed until the arcuate fibers after the nuclei cuneatus and gracilis.
According to Arce et al, crimes of violence account for approximately 26% of traumatic spinal cord injuries in America. Though Brown-Sequard syndrome is comparatively rare, it is important to consider in cases of penetrating trauma due to the serious nature of the injury. They then go on to discuss the imaging modalities that can be used to evaluate spinal cord injuries such as MRI.
Johnson et al. discuss a case report highlighting the association of Brown-Sequard syndrome with Horner's syndrome in lesions that occur in the neck. It is important to keep in mind that the sympathetic fibers that run in the spinal cord can be damaged in hemicord lesions above the level of T1 and can therefore lead to a unilateral Horner's syndrome on the side of the lesion. Horner's syndrome classically presents with ptosis, miosis, and anhydrosis.
The provided illustration shows the localization of the long tracts that are damaged in the lesion causing Brown-Sequard syndrome. Notably the spinothalamic tract has already crossed therefore causing a contralateral loss of pain and temperature sensation.
Answer 1: Anterior cord lesions would present with a bilateral loss of pain and temperature sensation with bilaterally symmetric weakness.
Answer 2: Posterior cord lesions would present with a bilateral loss of proprioception, vibration, and light touch sensation.
Answer 3: A right cord hemisection would present with right sided weakness and a left sided loss of pain and temperature sensation
Answer 5: A complete cord transection would present with absent neurologic function bilaterally below the level of the lesion.
Arce D, Sass P, Abul-Khoudoud H. Recognizing spinal cord emergencies. Am Fam Physician. 2001 Aug 15;64(4):631-8. Review. Erratum in: Am Fam Physician 2002 May 1;65(9):1751.
PMID:11529262 (Link to Abstract)
Johnson S, Jones M, Zumsteg J. Brown-Séquard syndrome without vascular injury associated with Horner's syndrome after a stab injury to the neck. J Spinal Cord Med. 2015 Feb 9.
PMID:25659820 (Link to Abstract)