**1. Introduction**

Root syndrome diagnostics of the lower extremity is based on the clinical picture, anamnesis, symptoms and signs of the disease. Diagnostic investigations should be considered in a few weeks if symptoms are not resolved, or even earlier if paraparesis or bowel or bladder symptoms develop. Current imaging studies are excellent, but there is the problem with non-symptomatic degenerative changes vs. relevant findings with respect to the acute symptoms, especially in middle-aged and old patients. ENMG has another problem: after acute onset of the disease the proprioceptive tendon- and H-reflexes change in a few days. However, the development of pathological spontaneous activity, fibrillations and positive sharp waves, indicating axonal injury in electromyography (EMG) may take 2-3 weeks and even longer in distal muscles of the leg and foot [1]. Loss of motor units during maximal voluntary contraction may be observed soon, but more distinct changes, such as increase of duration, complexity (polyphasic and jittering waveform), and amplitude of motor unit potentials after parallel reinnervation may take several weeks and even months to develop [2]. That is why ENMG studies are usually not performed until several weeks after the acute onset stage. The aim of this chapter in to describe some proprioceptive reflexes, which may be used in acute stage of the disease, when clear needle EMG findings are not yet discernible, and proprioceptive reflex measurements which may be further developed for the ENMG diagnostics of root syndromes of the lower extremity.

### **1.1 Routine electroneurography in root syndromes of the lower extremity**

Electroneuromyography of root syndromes of the lower extremity tends to concentrate on function of motor nerve fibres. Needle EMG observes axonal damage with fibrillation potentials, and loss and sprouting alterations of motor unit potentials. Signs of axonal damage may be searched in different myotomes of the lower extremity and paraspinal muscles [2]. F-responses and amplitudes of the motor responses may give supplementary information. The sensory responses are not affected, if the root lesion is proximal to the sensory paraspinal ganglion.

#### **1.2 Pain in root syndromes and the methods to study the posterior roots**

However, pain is usually more prominent symptom in root syndromes than motor weakness. Pain may express itself in the dermatomes of different root levels but often pain symptoms are obscure. The pain pathway uses the posterior roots, which may have a separate or more prominent injury than the anterior motor roots. ENMG study involving only motor nerve fibres may not be sufficient for the proper diagnosis of a root syndrome. Methods for studying the integrity of the posterior roots are needed. Posterior root compression may cause activation of pain C-fibres, but this may not invariably change proprioceptive reflexes using sensory afferent pathways with myelinated nerve fibres. Dermatomal evoked responses have been used, but they have not got any wide popularity. The method is awkward and timeconsuming and the cerebral responses are small. This method is not recommended for clinical use [3].

#### **1.3 H-reflexes of the distal muscles**

Proprioceptive reflexes, especially H-reflexes, which use the posterior root pathway are too seldom used in ENMG diagnostics [4]. The only reflex we have routinely measured in patients with root syndrome is H-reflex of the soleus muscle. Its recording is easy, non-invasive and rapid, and very useful in S1 root syndrome diagnostics. It may also be used as a part of measurements to study polyneuropathy, an entity that should also be evaluated when root syndromes are investigated. Damage of the S1 posterior root often abolishes the H reflex response or causes slight prolongation or diminution of the reflex response [4]. Compression and injury of the anterior root is observed as a marked prolongation of the latency and diminution of the response amplitude (**Figure 1**). The clinical use of the soleus H-reflex requires a comprehensive normal material, which comprises corrections for height and age and sex of the patient (**Table 1**) [5].

We have not used systemically any H-reflexes of L5 and L4 levels. The H-reflex of the anterior tibial muscle may be recorded with slight tonic voluntary contraction

**39**

**Table 1.**

**Figure 1.**

(R2

*also the large difference in the M-amp/H-amp relationship.*

**Distal latency (ms) SD H-latency** 

*Recording of Proprioceptive Muscle Reflexes in the Lower Extremity*

*H-reflex in the healthy (A) and symptomatic (B) side of a patient with S1 root syndrome. Note the diminution of amplitude and large latency value of the H-reflex response in the symptomatic side, compared to the healthy one. The relatively large reflex asymmetry and good persistence also in the symptomatic side is consistent with S1 anterior root compression. The" H-M lat" describes the deviation in Z score value (normal <2) of the measured H-reflex latency from normal control values with height, age and sex corrections (Table 1). Note* 

**(ms)**

4.13 0.50 29,18 2.18

64 1.325 −6.239 0.193 0.085

Calculation of the expectation value: constant + hc x height (cm) + ac x age + sex (male).

*electrodes near the border of the gastrocnemius muscle and the reference 2–3 cm distally).*

68 1.256 −15.210 0.247 0.094 −1.45

*Normal values and presumed normativity of the tibial H-reflex measured from the soleus muscle (surface* 

Calculation of the presumed normativity and the expectation percentage: (R2

) x 100 SD Constant Height

48 1.562 2.110 0.160

**SD**

coefficient (hc)

) x 100 of the tibial H-reflex.

sex

Age coefficient (ac)

*DOI: http://dx.doi.org/10.5772/intechopen.95575*

*Recording of Proprioceptive Muscle Reflexes in the Lower Extremity DOI: http://dx.doi.org/10.5772/intechopen.95575*

#### **Figure 1.**

*Proprioception*

ganglion.

for clinical use [3].

**1.3 H-reflexes of the distal muscles**

for height and age and sex of the patient (**Table 1**) [5].

root syndromes of the lower extremity.

maximal voluntary contraction may be observed soon, but more distinct changes, such as increase of duration, complexity (polyphasic and jittering waveform), and amplitude of motor unit potentials after parallel reinnervation may take several weeks and even months to develop [2]. That is why ENMG studies are usually not performed until several weeks after the acute onset stage. The aim of this chapter in to describe some proprioceptive reflexes, which may be used in acute stage of the disease, when clear needle EMG findings are not yet discernible, and proprioceptive reflex measurements which may be further developed for the ENMG diagnostics of

**1.1 Routine electroneurography in root syndromes of the lower extremity**

Electroneuromyography of root syndromes of the lower extremity tends to concentrate on function of motor nerve fibres. Needle EMG observes axonal damage with fibrillation potentials, and loss and sprouting alterations of motor unit potentials. Signs of axonal damage may be searched in different myotomes of the lower extremity and paraspinal muscles [2]. F-responses and amplitudes of the motor responses may give supplementary information. The sensory

responses are not affected, if the root lesion is proximal to the sensory paraspinal

However, pain is usually more prominent symptom in root syndromes than motor weakness. Pain may express itself in the dermatomes of different root levels but often pain symptoms are obscure. The pain pathway uses the posterior roots, which may have a separate or more prominent injury than the anterior motor roots. ENMG study involving only motor nerve fibres may not be sufficient for the proper diagnosis of a root syndrome. Methods for studying the integrity of the posterior roots are needed. Posterior root compression may cause activation of pain C-fibres, but this may not invariably change proprioceptive reflexes using sensory afferent pathways with myelinated nerve fibres. Dermatomal evoked responses have been used, but they have not got any wide popularity. The method is awkward and timeconsuming and the cerebral responses are small. This method is not recommended

Proprioceptive reflexes, especially H-reflexes, which use the posterior root pathway are too seldom used in ENMG diagnostics [4]. The only reflex we have routinely measured in patients with root syndrome is H-reflex of the soleus muscle. Its recording is easy, non-invasive and rapid, and very useful in S1 root syndrome diagnostics. It may also be used as a part of measurements to study polyneuropathy, an entity that should also be evaluated when root syndromes are investigated. Damage of the S1 posterior root often abolishes the H reflex response or causes slight prolongation or diminution of the reflex response [4]. Compression and injury of the anterior root is observed as a marked prolongation of the latency and diminution of the response amplitude (**Figure 1**). The clinical use of the soleus H-reflex requires a comprehensive normal material, which comprises corrections

We have not used systemically any H-reflexes of L5 and L4 levels. The H-reflex of the anterior tibial muscle may be recorded with slight tonic voluntary contraction

**1.2 Pain in root syndromes and the methods to study the posterior roots**

**38**

*H-reflex in the healthy (A) and symptomatic (B) side of a patient with S1 root syndrome. Note the diminution of amplitude and large latency value of the H-reflex response in the symptomatic side, compared to the healthy one. The relatively large reflex asymmetry and good persistence also in the symptomatic side is consistent with S1 anterior root compression. The" H-M lat" describes the deviation in Z score value (normal <2) of the measured H-reflex latency from normal control values with height, age and sex corrections (Table 1). Note also the large difference in the M-amp/H-amp relationship.*


#### **Table 1.**

*Normal values and presumed normativity of the tibial H-reflex measured from the soleus muscle (surface electrodes near the border of the gastrocnemius muscle and the reference 2–3 cm distally).*

#### **Figure 2.**

*H-reflex of peroneus longus, 32 years old male. Stimulation with 2 cm bipolar surface electrode to common peroneal nerve at the fibular head causing clear ankle dorsiflexion; ten concurrent stimulations with increasing stimulation current. Simultaneous recording of peroneus longus with both surface electrodes (interelectrode distance ca 3 cm), a 30 G concentric needle electrode, and soleus with surface electrodes (interelectrode distance ca 3 cm). Note the typical appearance of H-wave, latency 32 ms (vertical line), reaching its maximal amplitude before M-wave (contrary to the performance of F-responses) and appearance of H-wave solely on peroneus longus and not on soleus. 2 mV/div, 8 ms/div. A similar recording with surface electrodes on the lateral gastrocnemius muscle was also performed and no reflex response of this muscle was observed (not shown).*

of the given muscle [4], but we have found it too difficult for routine use. No H-reflex for the L5-level was described for clinical use in root syndromes. We have tried to measure H-reflexes of the peroneus longus and extensor hallucis longus muscles, but these measurements were hampered by volume conduction of reflexes of the triceps surae muscle. However, H-reflex of the peroneus longus muscle can be confirmed by recording it with EMG needle electrode (**Figure 2**). The peroneus longus H-reflex may disappear in the symptomatic side of a patient with unilateral L5 root syndrome (**Figure 3**). Problems with volume conduction are discussed at the end of this chapter.
