More than expected head dropped myasthenia onset are patient with Parkinson disease (25%) and majority of myasthenia onset in patient with Parkinson disease is head dropped (more tan 60%). We think that it may be due to fatigability associated to cervical rigidity. What do you think?
Dear Josep,
That is an interesting question. I wonder whether this is due to reduction in descending inputs to cervical Motoneuron pools, changes in intrinsic properties of cervical motoneurons (such as inability to sustain firing), or reduction in the muscle or motor units? Or all of these listed above? In general, fast twitch motor units to go with aging, but may be with disease, slow twitch or slow fatigue motor units are also lost early. To keep head posture up requires a lot of muscle strength and sustained neuromuscular activity. Do you think the reduction in neuromotor activity starts centrally or peripherally? For inspiration you may want to check my recent review on that topic.
best wishes, Refik
Article Emerging Roles of Filopodia and Dendritic Spines in Motoneur...
Question: we have observed that a frequent myasthenia onset in Parkinson disease is a head dropped syndrome. Do you think that it is due to cervical rigidity?
Reply: No this symptom is not attributable to rigidity of the neck. On the contrary, it is an independent symptom due to weakness of the neck muscles – a very common symptom in myasthenia gravis – and frequently occurring in non-Parkinson patients as well.
The question was why is more freqüent and characteristic head dropped myasthenia onset in parkinsonian patient. Could it be due to fatigability of extensors muscles of the neck secundary to flexor rigigidity?
I aggree to Finn, head dropped syndrom is very frequent in MG patients sometimes overlooked, I think that it is not caused by Parkinson.
I think head drop syndrome is a feature of myasthenia gravis.It is not caused by Parkinson, S disease
Rigidity and fatigability are probable causes hor head drop in this patient. Head drop is also frequent in MG, especially in MuSK positive. In older also patients EMG often discloses denervation in cervical paraspinal muscles as well as myopathic potentials.
Interesting question Sir. Can you share your reference to the numbers you cited (25% and 60%) ? I apologize if I understood your question wrong, but the extensor muscle weakness of neck in myasthenics is a well known phenomena. They have neck drop as a result. In fact the dropped neck is a clinical indication used by critical care neurologists widely to say whether the patient is likely to go in for respiratory failure (cervical and diaphragmatic muscles share C3-5 myotomes). However I can imagine that head-drop may be a more prominent feature if a parkinson patient develops myasthenia, because if a patient already has some rigidity in the flexors of the neck due to Parkinsonism, it would be easier for the head-drop to happen when myasthenia weakens the extensors of the neck. Is this what your original point was about ?
I think that whichever being the origin, if muscle hyperactivity is present it causes fatgability at neuromuscolar junction level and then dropped head syndrome; obviously, if the cause if cervicoarthrosis, it doesn't matter
Yes, may original point was about this. We have a parkinsonian patient with dropped head myastehnia onset without other myasthenic simptom. We reviwed literature, and we are writting a paper. We think that dropped head is a caracteristic onset of myasthenia in Parkinson disease, and often dropped head is the only simptom.
Dear Josep,
This is an interesting observation and question.
I would like to agree to Finn Somnier and Berthold Schalke. My Impression is that in particular late-onset myasthenia gravis frequentlly presents with dropped head syndrome. On the other hand we published a case with parkinsonism and myositis of the paraspinal muscles mimicking camptocormia. Thus, it would perhaps be interesting to perform EMG of cervical paraspinal muscles and MRI of the cervical spinal cord to exclude myosits of cervical parapsinal muscles in your patient..
EMG of paraspinal muscle was diagnostic of MG. After prednisona therapy, head drop improve, and 2 month later was resolt. We have a register of myasthenia with 100 patient (50% over age 75) and this patient was the only whose onset (initial and exclusive simptom) was a head drop
Maybe the explanation is more simple? If you look at the posture of a patient with PD, he is classically slightly bent forward, with sometimes neck extension. So if you get MG as concomitant disease, the posture of PD favors head drop when muscles are touched by MG. Did you look for the typical myasthenia time course, i.e. worsening during the day?
I agree with comments above. You need to look for a paraspinous myopathy. The etiology of which is not known but may be related to hyperextension injury of neck muscles, which could occur with increased weakness from MG or altered posture from PD. From a therapy perspective you need to assess if this is MG or not.
EMG of paraspinal muscle was diagnostic of MG, and dind'nt show myopathy. Anti antiAChR were high (41). Improve after corticoide therapy. We think dropped head is secundary to myashenia (only amb onset simptom) in this case and others revised), and we agree that hiperactivity secundary to neck rigidity favor head drop caracteristically in Parkinson disease
I think that head dropped remains The effect of muscular weakness related to myasthenia; fibers' contraction could acta si a fatigating mecanism.
- Badges
- Science topic
- Similar topics
- Correction