Unilateral H-reflex

[PMR 4 MSK]

A patient complains of LLE numbness, no symptoms on the right. LLE NCS including peoneal and tibial motors and F-waves are normal. LLE sensories are normal. Needle exam is normal.

If the left H-reflex is also normal for age and height, is there any value in doing a right H-reflex for comparison? I.e. if there is a side-to-side discrepency, with both sides being WNL by themselves, would it matter or change anything in light of everything else being normal?

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[Ludicolo]

Comparing side-to-side latency differences could be helpful to document abnormality vs. complete normalcy if this is work comp or medicolegal. From a clinical management standpoint though – doesn’t change a thing.

 

[latinman]

You mean like calling a S1 radic based on the H-wave latency being slightly prolonged on one leg compared to another. Hmm, I am not sure.

Did this pt have any weakness clinically in toe flexors or plantarflexion? What about sensation and reflexes (ie., S1 dermatome and Achille's)?


I am not sure what is your question, but I wouldn't call a S1 radiculopathy based only on a H-reflex, unless I have other evidence on clinical exam to sustain it. I am not sure what the other OP's have to say about it. Maybe someone can pull up some studies...

 

[olafa]

A patient complains of LLE numbness, no symptoms on the right. LLE NCS including peoneal and tibial motors and F-waves are normal. LLE sensories are normal. Needle exam is normal.

If the left H-reflex is also normal for age and height, is there any value in doing a right H-reflex for comparison? I.e. if there is a side-to-side discrepency, with both sides being WNL by themselves, would it matter or change anything in light of everything else being normal?

Part of what we were taught was that was the whole point of doing H-reflex- to compare side to side. As the sural may be absent in the aging population, the h-reflex may also be difficult to obtain and unless you do bilateral (with unilateral symptms presenting) it would be difficult ascertain the interpretation of the result.

But would also expect contributing findings on EMG too.

 

[topwise]

I think what Ludicolo said makes the best sense. Would anyone call an S1 radic based solely on the H-reflex being normal but prolonged compared to the other side? But for documentation/medicolegal purposes, it probably makes sense to do both sides. Also, if the symptoms significantly worsen down the road and the study is repeated, might be good to know what it was on the original study.

Follow-up question: if LLE NCS including peoneal and tibial motors and F-waves are normal, LLE sensories are normal, and needle exam is normal, is it necessary to do H's at all?

 

[drusso]

What's the distribution of the numbness? The whole limb? The top of of the foot? Small spot between great and second toe? Behind the knee? Are they ataxic?

Is this acute or chronic? Did they just come from getting their H1N1 shot?

 

[Ludicolo]

What's the distribution of the numbness? The whole limb? The top of of the foot? Small spot between great and second toe? Behind the knee? Are they ataxic?

Is this acute or chronic? Did they just come from getting their H1N1 shot?

How dare you and latinman use EDX testing as an extension of your history and physical exam.

Follow-up question: if LLE NCS including peoneal and tibial motors and F-waves are normal, LLE sensories are normal, and needle exam is normal, is it necessary to do H's at all?

Check H’s if your NCS/EMG is otherwise normal and 1) you still have a strong clinical suspicion about a unilateral S1 radic, 2) you feel the need to prove it, and 3) you will change your management based on the result.

I personally don’t think H’s add anything useful to the EDX study and how they’re used to guide clinical management. I don’t do them in my patients. Well, that’s not entirely true. I tap on the Achilles tendons a couple of times on almost all of my patients.

 

[RUOkie]

How dare you and latinman use EDX testing as an extension of your history and physical exam.



Check H’s if your NCS/EMG is otherwise normal and 1) you still have a strong clinical suspicion about a unilateral S1 radic, 2) you feel the need to prove it, and 3) you will change your management based on the result.

I personally don’t think H’s add anything useful to the EDX study and how they’re used to guide clinical management. I don’t do them in my patients. Well, that’s not entirely true. I tap on the Achilles tendons a couple of times on almost all of my patients.

I agree 100%. I have not done an H-reflex in years. I personally would not call a radiculopathy based solely on a prolonged H-reflex. If you are going to test them, I personally feel that you need to compare the other side. It just does not add to the study (and often makes things more ambiguous).

Check reflexes on all patients. It takes less time, and gives better clinical results.

 

[RUOkie]

Part of what we were taught was that was the whole point of doing H-reflex- to compare side to side. As the sural may be absent in the aging population, the h-reflex may also be difficult to obtain and unless you do bilateral (with unilateral symptms presenting) it would be difficult ascertain the interpretation of the result.

OK, if the Sural SNAP is absent, there is a sensory nerve problem. Period. Unless you are having technical problems (ie. obesity, severe edema etc.). I can find Sural SNAPs on people in their 90's and older (I recently had a normal BLE study in a 101 y/o woman!)

 

[PMR 4 MSK]

Mostly this is a mental exercise/thought provocation.

The pt is real, just saw her last week, everything was normal, including H-reflexes on both sides, no significant latency difference. Afterward, I was thinking about what the value is in getting the contralateral H-reflex, when the involved side is normal and everthing else is normal. Basically, would it change anything?

My thought process is no, it wouldn't.

BTW, pt was complaining of vague left leg numbness, no specific distribution, just "my leg feels numb." Referring doc ordered EMG. No weakness, nothing on PE.

 

[olafa]

since distribution is vague and non-dermatomal- could be vascular.
Is she an athlete?
There are cases reported in elite athlete and because of repetitive over-use they will get vascular endofibrosis. (baseball, cycling.... etc). Dignosis will dynamic vascular studies. Stationary will often be normal.

 

[RUOkie]

Mostly this is a mental exercise/thought provocation.

The pt is real, just saw her last week, everything was normal, including H-reflexes on both sides, no significant latency difference. Afterward, I was thinking about what the value is in getting the contralateral H-reflex, when the involved side is normal and everthing else is normal. Basically, would it change anything?

My thought process is no, it wouldn't.

BTW, pt was complaining of vague left leg numbness, no specific distribution, just "my leg feels numb." Referring doc ordered EMG. No weakness, nothing on PE.

At the same time, what we were saying was "What is the value of the IPSILATERAL H-Reflex?"

 

[olafa]

Alice Walmesley, PhD, Dianthus Medical LimitedThe H reflex from the abductor brevis hallucis muscle in healthy adultsBody_ID: PUP20071126A001The H reflex is a monosynaptic reaction of muscles after electrical stimulation of sensory fibers. It can be used to assess spinal reflex excitability and provide information about conduction in proximal segments of peripheral nerve fibers. The conduction velocity of Ia afferents can be estimated by eliciting an H reflex at two different points from the same peripheral nerve. This reflex has been studied extensively in muscles such as the soleus, quadriceps, and radial flexor and may be useful in diagnosing disorders of the peripheral nervous system. The reliability of measurement of a given parameter is determined by the degree of variability shown.Body_ID: PUP20071126A002A recent study evaluated the occurrence and reliability of the H reflex from the abductor brevis hallucis (ABH) muscle in the foot. The study involved 43 subjects, 19-82 years old, with no history of peripheral or central nervous system diseases. Three patients with cauda equina syndrome also were examined. Bipolar recordings were made using surface electrodes, with the active electrode on the ABH and a reference electrode on the proximal phalanx of the big toe. The tibial nerve was stimulated with bipolar surface electrodes. The distal conduction velocity of Ia afferent fibers was measured by stimulation of the tibial nerve at the ankle in 20 subjects. The stimulus was 0.1 Hz, 6-27 mA for 1 ms, and skin temperature of the conduction path was maintained with an infrared lamp. Parameters of maximal H reflex (Hmax) amplitude and latency, Hmax-to-Mmax amplitude ratio, and Hmax latency and amplitude differences were measured using single-point and test-retest in normal limits. A linear regression analysis was used to assess the effects of height and age, and reliability was assessed by the intraclass correlation coefficient (ICC).Body_ID: PUP20071126A003An H reflex was detected in 36 of the 43 subjects. The Hmax latency was affected by height (Hmax latency = 0.285 × h - 9.38; P < .001), but not age. This also has been shown in studies involving the soleus muscle. ICC was rated as excellent for all parameters except for the intersession Hmax, which showed only “fair” reliability.Body_ID: PUP20071126A004In patients with cauda equina syndrome, the H reflex was significantly reduced or absent in the ABH muscle on the affected side or was absent bilaterally.Body_ID: PUP20071126A005The H reflex from the ABH had a small amplitude overall. It was recordable from the soleus muscle, but not the ABH in 7 of 11 subjects >60 years old, possibly relating to an age-related loss of neurons. There was an overall age-related decline in the H reflex, which was more pronounced in taller subjects. The H reflex parameters of Hmax and Hmax-to-Mmax amplitude were reliable, showing excellent consistency between intrasession and intersession measurements, but Hmax amplitude was more variable.Body_ID: PUP20071126A006In conclusion, the H reflex was found to be a reliable method for evaluating the S2 root, but distal conduction velocity of Ia fibers was more variable. The H reflex of the ABH and soleus muscles may provide useful information in patients with cauda equina syndrome, but further work is needed to confirm thisBody_ID: NoneVersino M, Candeloro E, Tavazzi E, et al: The H reflex from the abductor brevis hallucis muscle in healthy adults. Muscle Nerve 36(1):39-46, 2007.