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conus medullaris syndrome

conus medullaris



It is a clinical subset of spinal cord injury syndromes. Injuries at the level of T12 to L2 vertebrae are most likely to result in conus medullaris syndrome.


What Causes Conus Medullaris Syndrome?

Conus medullaris syndrome isn’t a disease in its own right , but rather the product of a spinal trauma. In most cases, a blow to the back; such as from a car accident or gunshot is to blame. But some diseases, notably spinal cord infections, malformations of the spinal column due to spinal stenosis, and spinal tumors can also cause the syndrome.



  • Lumbar stenosis (multilevel) .
  • Spinal trauma including fractures. 
  • Herniated nucleus pulposus.
  • Neoplasm, including metastases, astrocytoma, neurofibroma, and meningioma; 20% of all spinal tumors affect this area .
  • Spinal infection/abscess (tuberculosis, herpes simplex virus, meningitis, meningovascular syphilis, cytomegalovirus, schistosomiasis).
  • Idiopathic (spinal anesthesia ): these syndromes may occur as complications of the procedure or of the anesthetic agent (hyperbaric lidocaine, tetracaine) .
  • Spina bifida and subsequent tethered cord syndrome .



  • Spinal hemorrhage , especially subdural and epidural hemorrhage causing compression within the spinal canal
  • Intravascular lymphomatosis
  • Congenital anomalies of the spine/filum terminale, including tethered cord syndrome
  • Conus medullaris lipomas
  • Multiple sclerosis
  • Spinal arteriovenus malformations
  • Late-stage ankylosing spondylitis
  • Neurosarcoidosis
  • Deep venous thrombosis of the spinal veins (propagated)
  • Inferior vena cava thrombosis

SYMPTOMs of C.M syndrome

  • Severe back pain
  • Strange or jarring sensations in the back, such as buzzing, tingling, or numbness
  • Bowel and bladder dysfunction, such as difficulty controlling your elimination functions
  • Sexual dysfunction
  • Weakness, numbness, or tingling in your lower limbs
  • Sensations in your lower limbs that aren’t caused by a clinical issue. For instance, you might have itchiness in your leg that is not well-explained by an allergic reaction or other issue.

Conus medullaris syndrome VS Cauda equina syndrome

  • The symptoms and signs of cauda equina syndrome tend to be mostly lower motor neuron (LMN) in nature, while those of conus medullaris syndrome are a combination of LMN and upper motor neuron (UMN) effects
  • Conus medullaris syndrome manifest symptoms that are similar to cauda equina syndrome, but the two conditions require different treatment. Conus medullaris typically produces sudden symptoms on both sides of the body, while cauda equina syndrome usually develops over time, producing uneven symptoms concentrated on one side of the body.

Some other criteria that can help you differentiate one from the other include: 

  • Cauda equina typically causes severe pain, while conus medullaris results in mild to moderate pain, if any pain at all is present. 
  • Conus medullaris can be caused by an injury, lesion, or infection, while cauda equina is almost always caused by a lesion or infection. 
  • Cauda equina may eliminate the patellar and Achilles reflexes, while conus medullaris typically only interferes with the Achilles reflex. 
  • Conus medullaris is more likely than cauda equina to result in pain concentrated in the lower back. 
  • Impotence is more common with conus medullaris than cauda equina. 

Muscle strength of the following muscles should be tested to determine the level of lesion:

  • L2 – Hip flexors (iliopsoas)
  • L3 – Knee extensors (quadriceps)
  • L4 – Ankle dorsiflexors (tibialis anterior)
  • L5 – Big toe extensors (extensor hallucis longus)
  • S1 – Ankle plantar flexors (gastrocnemius/soleus)

Also Read: low Back Pain

Radiographic features

  • MRI with contrast of the lumbosacral spine is the diagnostic test of choice and provides a more complete radiographic assessment of the spine than other tests. Gadolinium contrast MRI is currently the most sensitive imaging for detecting intradural neoplasms. It also may be able to rule out abdominal aneurysm, which could be the source of emboli causing conus medullaris infarction. See Images 3-5 for representative MR images.
  • CT scan myelogram may reveal an intradural or extradural mass or lesions affecting the conus medullaris.
  •  Plain radiographs of the lumbosacral spine are still useful and may depict early changes in vertebral erosions secondary to tumors and spina bifida. Chest radiography is indicated to rule out a pulmonary source of pathology that could affect the lumbosacral spine (eg, malignant tumor, tuberculosis). Follow-up chest CT may be required.
  • Bone scan may detect malignant tumor or metastases and inflammatory conditions affecting the vertebrae.
spinal cord injuries: spinal cavernoma
Case1: spinal cavernoma
spinal cord injury : metasis
Case 2: metastasis

Treatment & Diagnosis

The prognosis depends on upon the timing of patient presentation, the severity of deficits and underlying pathology. Early diagnosis and treatment may facilitate improvement in symptoms. Approximately 10% of patients may regain functional recovery.


Conus medullaris infarction should be considered in the differential diagnosis, and a source of emboli should be sought by ultrasound to rule out an abdominal aortic aneurysm. Heterotopic ossification should be ruled out by triple-bone scan in a patient with pain and swelling of the lower extremity in whom deep venous thrombosis (DVT) has been ruled out. In other words, heterotopic ossification should always be considered as a differential diagnosis of DVT in these patients.

The differential diagnosis centers on non-compressible causes of spinal cord dysfunction such as:

  • Spinal cord infarct ​
  • HIV-related myelopathy ​
  • Transverse myelitis ​
  • Multiple sclerosis ​
  • Syringomyelia ​
  • Spinal arteriovenous malformation ​
  • Acute Inflammatory Demyelinating Polyradiculoneuropathy.
  • Amyotrophic Lateral Sclerosis in Physical Medicine and Rehabilitation.
  • Diabetic Neuropathy.
  • Guillain-Barré Syndrome.
  • Neurosarcoidosis.
  • Spinal Cord Infections.
  • Traumatic Peripheral Nerve Lesions.


  • Spinal decompression surgery often helps.
  • If a physical impediment to function remains; such as a tumor or the remnants of a bullet—your doctor may remove these to restore spinal function.
  • Radiation may help if your symptoms are due to cancer. 
  • And if an infection caused the symptoms, or your injury is so severe it led to an infection, you may need intravenous or oral antibiotics.

 You will likely also need physical therapy to regain function.

Also Read : Translatoric_Spinal_Manipulation_for_Physical_Therapists_Book_-pdf

Role of physiotherapist

  • Range of motion and strengthening exercises.
  • Sitting balance.
  • Transfer training.
  • Tilt table as tolerated (because of tendency to orthostatic hypotension). Tilt table should start at 15 degrees, progressing by 10 degrees every 15 minutes up to about 80 degrees with the necessary precautions.
  • Other activities include wheelchair propulsion training, standing table exercises, functional electrical stimulation for increased muscle tone, use of lower extremity orthoses to aid balance and walking, along with ambulation exercises, family training and community skills, and a home exercise program.

Patient Education

  • Patient education needs will vary with the type and severity of persistent deficits, and may include the following:
  • Training in self-catheterization and finger fecal disimpaction , if required
  • Use of measures to prevent pressure ulcers, such as skin inspection/care, positioning, turning and transferring tactics, use of skin protectors, or pressure-reducing support surfaces
  • Maintenance of endurance and strength-training exercises
  • Regular follow-up by the consulting teams who treated the patient in the hospital
  • Instructions on how and when medications should be taken and when follow-up laboratory tests should be performed


Article Name
Conus Medullaris Syndrome
Conus Medullaris Syndrome is a type of incomplete spinal cord injury that is less likely to cause paralysis than many other types of spinal cord injuries.
Publisher Name
Randa Naser

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