This is the most common location of the lesion, and therefore most individuals will have weakness of the lower limbs.A lesion of the lumbar segment, the lower part of the spinal cord (L1–S5) often produces a combination of upper and lower motor neuron signs in the lower limbs. Lumbar lesions account for about 10% of cases. Causes
TM is a heterogeneous condition, that is, there are several identified causes. Sometimes the term Transverse myelitis spectrum disorders is used. In 60% of patients the cause is idiopathic. In rare cases, it may be associated with meningococcal meningitisWhen it appears as a comorbid condition with neuromyelitis optica (NMO), it is considered to be caused by NMO-IgG autoimmunity, and when it appears in multiple sclerosis (MS) cases, it is considered to be produced by the same underlying condition that produces the MS plaques.Other causes of TM include infections, immune system disorders, and demyelinating diseases. Viral infections known to be associated with TM include HIV, herpes simplex, herpes zoster, cytomegalovirus, and Epstein-Barr. Flavivirus infections such as Zika virus and West Nile virus have also been associated. Viral association of  transverse myelitis could result from the infection itself or from the response to it. Bacterial causes associated with TM include Mycoplasma pneumoniae,  Bartonella henselae, and the types of Borrelia that cause Lyme disease. Lyme disease gives rise to neuroborreliosis  which is seen in a small percentage (4 to 5  per cent) of acute transverse myelitis cases.
The patient should also be catheterized to test for and, if necessary, drain an over-distended bladder. A lumbar puncture can be performed after the MRI or at the time of  CT myelography. Corticosteroids are often given in high doses when symptoms begin with the hope that the degree of inflammation and swelling of the spinal cord will be lessened, but whether this is truly effective is still debated. Differential diagnosis
The differential diagnosis of acute TM includes demyelinating disorders, such as multiple sclerosis and neuromyelitis optica, infections, such as herpes zoster and herpes simplex virus, and other types of inflammatory disorders, such as systemic lupus erythematosus and neurosarcoidosis. It is important to also rule out an acute cause of compression on the spinal cord. Treatment
If treated early, some people experience complete or near complete recovery. Treatment options also vary according to the underlying cause. One treatment option includes plasmapheresis. Recovery from TM is variable between individuals and also depends on the underlying cause. Some patients begin to recover between weeks 2 and 12 following onset and may continue to improve for up to two years. Other patients may never show signs of recovery. Prognosis
The prognosis for TM depends on whether there is improvement in 3 to 6 months. Complete recovery is unlikely if no improvement occurs within this time. Incomplete recovery can still occur; however, aggressive physical therapy and rehabilitation will be very important. One-third of people with TM experience full recovery, one-third experience fair recovery but have significant neurological deficits, such as spastic gait.