Radiculopathy vs. Pseudoradiculopathy. How to make differential diagnosis?

Autor: Mgr. Lukáš Kasala - physiotherapist and RehaThink instructor



Patient has irradiation to lower or upper extremity, so it is radiculopathy. Or not? How to make differential diagnosis betwenn radiculopathy and pseudoradiculopathy? How to recognise? What can cause pseudoradiculopathy?

For sure your ambulance has visited patient whose has irradiaton to the extremity. Usually this patient has visited before neurologist whose did MRI and found some disc herniation. Usually this is described as a reason why patient feels the irradiation. Diagnosis- radiculopathy. But, it is not that easy.

To distinguish between radiculopathy and pseudoradiculopathy can be tricky. Radiculopathy means that there is compression of the nerve root with disc, osteofyt, spinal or intervertebral foraminal stenosis, tumor, edema, ... Radiculopathy is always presentd with a neurological signs. In pseudoradiculopathy symptoms are similar, but there are not neurological signs.


This topic is discussed in detail in course "Global Trigger point therapy: I part". In course you will learn practical assessment and therapy techniques which focus on muscle inhibition -applying the principles of global reciprocal inhibition (RI) and PIR according to K. Lewit, as well as AEK (agistic-eccentric-contraction) according to the Brügger concept.


Radiculopaty

In radiculopathy syndrome, patient feels sharp back pain with projection into corresponding spinal root dermatome and a deficit in the sensation of the corresponding dermatome. Patient is able to clearly show where the pain goes (exatly shows that pain goes all the way to fingers) and this area corresponds with nerve root dermatome. Another symptoms can be ataxia of the involved extremity, weakness, triping or falling (lower extremity). Typical, but not specific sign can be pain during coughing or sneezing (1,2,6).


So signs for radiculopathy are:

1. pain projection into nerve corresponding dermatome;

2. paresthesia or dysesthesia, paresis, hypestesia, areflexia;

3. muscle weakness, atonia, muscle athrophy;

4. positive stretching maneuvers;

5. wake up at night while turning on bed;

6. antalgic posture - kyphosis and side bending;

7. the dynamics of the affected spinal segment are significantly limited, and movements that do not correspond to the antalgic positioning are painful.

8. the affected segment shows limited springing and it is extremely painful.


Typical presentations for lumbal radiculopathy:

L4 - pain irradiates to the knee, can a little bit further, but typical is to the knee. Patient can have just knee pain. Reversed lasegue is possitive (important is how you are performing test- knee flexion and hip extension have to be performed together !!!). There will be trigger point in rectus femoris. Weaken muscles are rectus femoris and whole quadriceps. Patient have problem with knee extension and hip flexion. In which position do we test it? In sitting. Why? Because in this position hip flexion is performed mainly with quadriceps, especially rectus femoris. Which reflex will be weaken? Patellar reflex. Patient can experience pain also in goin, also Patrick test can be possitive, so L4 can mimic knee and hip problem.


L5 - irradiates laterally along the thigh, then turns on the anterior part of the foreleg and goes to the big toe. Weaken muscle is always musclus extensor hallucis longus and another extensors (extensor digiturum brevis and tibialis anterior). Main is extensor hallucis longus because this has innervation just from L5. So for test we ask the patient to stand on the heels. Another very sensitive test is ask the patient in standing to lift just foot finger and we palpate m.extensor digitorum brevis. During walk we can typicaly see that big toe is not extended enough.Typical trigger point is in m.piriformis, so there is restricted hip internal rotation tested in 90° hip flexion. Which reflex will be weaken? In L5 we do not test reflex, because there is no clear L5 reflex.


S1 - pain irradiates on the dorsal side of the lower extremity to the little finger. The most affected muscle is triceps surae, so the patient will have problem to stand and walk on tip toes - walking is more sensitive test. Muscle athrophy we can see especially on the lateral side of the calf Another weaken muscles are gluteals. Weaken reflex is Achilles tendon reflex. But remember !!! If there is bilateraly lowered S1 reflex or areflexia, strong suspicious on cauda equina syndrome.


Typical discogenic disorders are monoradicular. If there is more radiculars, be careful, can be tumor, inflamation, narrow spinal canal,...

Do not rely only on MRI. Finding can be accidental and clinically not presented. Above age 25 most of the population has some changes on the spine which could cause pain. More specific is clinical assessment and what you can find with test.

Pseudoradicular syndrome

Pseudoradicular syndrome has very similar presentation to radicular, but is missing neurological sings.

What causes pseudoradicular syndrome? The cause is myofascial painful syndrome, which is presented with trigger points and joints blockades. Prof. Karel Lewit said that it is incomplete radicular syndrome, in which there is pressure on the sheath of the nerve root, but not on the nerve root itself. If there is joint blockade, there is changed segmental biomechanics and cause muscular tention in segment. This muscle tension presses on the sheath of the nerve root. Subsequently there occurs trigger points in corresponding muscles and can present with irradiation to extremity (1,-3).


Main difference from radiculopathy - pseudoradicular is difuse pain in reference zone, never in dermatome. Deep tendon reflexes are normal. Patient can report muscle weakness, paresthesia or dysesthesia, pain, but is in trigger point referrence zone, not clearly in dermatome. Possitive can be also Lasegue or reversed Lasegue test. In pseudoradiculopathy we don´t find areflexia, atonia, muscle atrophy. Muscle weakness can be presented but it is because of chronic muscle trigger point, not from nerve compression. There will not be possitive tests for muscle strenght. Patient won´t say "That extremity disobeys me". Pain is not just in dermatome, but regional and difuse, respectively, can cross the dermatome border (this won´t happen in radiculopathy).

Main presentation of pseudoradiculopathy is pain in reference zone. But sometimes it is more numbness or paresthesia than pain. Patient can have tenderness and dysesthesia in reference zone, which are very similar to radiculopathy (1,4).


Typical presentation of joints blockades of the lumbal spine (2):

L3-4, upper SI joint – pain to hip and groin, anterior aspect of the thigh, knee pain, trigger point in rectus femoris

L4-5 – pain irradiation alongside of the leg to the lateral malleolus, trigger point in piriformis and gluteus medius

L5-S1, lower SI joint – pain along back of the lower extremity to the heel, trigger point in hamstrings, gluteus minimus, calf.


Gluteus minimus trigger point presentation in L5 and S1 segment

On this picture we can see typical presentation of the gluteus minimus trigger point, which can mimic L5 or S1 radiculopathy. As you can see, the pain is not going exactly to dermatome, as well it do no go to the fingers. Patient shows the pain in the trigger points reffered zone, but not exactly in dermatome.





What is more often? Clearly it is pseudoradicular syndrome. Radiculopathy appears only in low percentages (1,2). Pseudoradicular syndrome is not rare, but quite often. Why physiotherapists should know to distinguish it? Because doctors don´t do it, or just occasionaly. Very often MRI finding is clinicaly irelevant and do not cause the pain. Radiculopathy and pseudoradiculopathy has partialy different therapy and different prediction. That is why we have to understand either it is radiculopathy or pseudoradiculopathy.


You can also see and understand, why for physiotherapists it is very important to understand joint blockades and trigger points presentation. Quickly and easy we can help the patient to relieve pain, just have to know how to unblock the joint, find and treat trigger point.


Literature:


  1. Kolář P. et al. 2014. Clinical Rehabilitation. Prague Rehabilitation School.

  2. Joseph M. Donnelly et al. 2018. Myofascial pain and dysfunction the trigger point manual 3rd edition.Lippincott Williams and Wilkins.

  3. Lewit, L. 2009. Manipulative Therapy: Musculoskeletal Medicine 1st Edition. Churchill Livingstone.

  4. https://www.sciencedirect.com/science/article/abs/pii/S0304395907002503

  5. https://journals.lww.com/pain/Citation/2008/04000/Pseudoradicular_and_radicular_low_back_pain__How.13.aspx

  6. https://www.tandfonline.com/doi/full/10.1080/10669817.2022.2092266