The patient has injured his left corticospinal tract (left-sided motor function), left dorsal columns (left-sided vibration and position), and left spinothalamic tract (right-sided pain and temperature), consistent with a left-sided Brown-Sequard syndrome.
Knowing where different sensory and motor tracts cross the midline is important for localization of different spinal cord lesions. The corticospinal tract, which carries efferent motor nerves from the brain, crosses in the pyramidal decussation in the caudal medulla. Therefore, a corticospinal tract lesion distal to the decussation will yield ipsilateral weakness. The afferent nerves in the dorsal columns also cross in the medulla, and therefore a lesion below the brainstem will cause ipsilateral loss of vibration and position below the lesion. In contrast, afferent nerves from the spinothalamic tract cross within 1-2 spinal cord levels and travel to the cortex on the contralateral side. Therefore, a lesion below the brainstem causes contralateral loss of pain and temperature.
Arce et al. discuss warning signs for spinal cord emergencies. These include acute neurologic deficit, significant trauma in patients <50 years, minor trauma in patients >50 years, and a history of steroids, osteoporosis, or cancer. In the absence of red flags, back pain alone does not warrant imaging unless symptoms have lasted more than 4 months.
Balaratnam and Pullicino discuss a patient who presented with acute-onset bilateral hand weakness, who was found to have anterior spinal artery ischemia. They note that the anterior horns represent the most distal part of the anterior spinal artery territory and that this area is therefore prone to ischemia.
Illustration A depicts spinal cord cross-sections in central cord syndrome (syringomelia), anterior cord syndrome, and a left-sided Brown-Sequard Syndrome. Illustration B is a chart of causes and symptoms of different spinal cord syndromes. Illustration C is an MRI of a patient with a syrinx, likely to cause central cord syndrome.
Answer 2: This lesion would produce right-sided weakness and loss of vibration and position sensation, and left sided loss of pain and temperature sensation.
Answer 3: This lesion would produce bilateral motor weakness and loss of pain and temperature sensation, with preserved vibration and position sensation.
Answer 4: This lesion would produce isolated, bilateral loss of vibration and position sense.
Answer 5: This lesion produces bilateral weakness (upper extremities > lower extremities), with possible associated loss of vibration and position sensation, but typically spares the dorsal columns.
Arce D, Sass P, Abul-Khoudoud H. Recognizing spinal cord emergencies. Am Fam Physician. 2001 Aug 15;64(4):631-8.
PMID:11529262 (Link to Abstract)
Balaratnam M, Pullicino P. Teaching NeuroImages: acute bilateral hand weakness from anterior spinal artery territory cord ischemia. Neurology. 2009 Jul 21;73(3):e13.
PMID:19620603 (Link to Abstract)