Question: Chronic Denervation or ‘Neurogenic Disorder’
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I am 53 and have a mild neuromuscular disorder but with debilitating fatigue. In 2007 I was diagnosed with Chronic Denervation or ‘Neurogenic Disorder’.

Q1: What is my ‘muscle fatigue’ (see below) called: is it weakness, fatigue, or exercise intolerance and is this typical of “chronic neurogenic change”?

Q2: Given that my mental fatigue has not abated in 5 years; my ‘exercise intolerance’ and muscle pain/fatigue is marginally worse should I pursue for other causes ie metabolic disorders?

Exercise intolerance/fatigue/weakness occurs with brief & intense i.e. repetitive hand grips, signing name, beating eggs, rapid foot movements, chewing large objects; muscle becomes stiff, fatigued painful lacks ‘strength’ with-in 10 – 30 seconds. If stop and rest i.e. swap hands can continue. Happened since childhood - no 'attacks' or episodes all the time.
Moderate exercise usually well tolerated although with some lasting fatigue and discomfort. No eye involvement. No ischemic exercise tests carried out.
‘Static exercise’ i.e. maintaining erect posture, standing still in one spot, etc. causes stiffness and a fatigueing/crampy pain. No evidence of myoglobinuria.
Chronic fatigue for +20 years – progressed from mild to current debilitating form.
Have had 2 major health 'crisis' or setbacks. First at age 7 yrs hospitalised with fever including encephalitis, 'suspected brucellosis' followed 12 months 'very sick' with muscle pain, ‘arthritis’ etc.
Second: 2006 onset of greater fatigue and cognitive issues, muscle aches, nerve pain, fasciculations, muscle stiffness, enlarged liver, etc.; Meds inc Epilim (sodium valproate) for ‘mood stabilizer?’; various antibiotics for suspected Q Fever; Mildly elevated CK 232 U/L
2007 diagnosed with Chronic Denervation or ‘Neurogenic Disorder’ after SFEMG & muscle biopsy for mito cytopathy – not screened for metabolic disorders – screen negative for KSS/CPEO). Tested Ddx: ALS, MS, MG, heart disease, etc.

Thank you for your consideration. I have seen two XXXXXXX neuroloogists - one diagnosed chronic fatigue & fibromyalgia, the second said "no fibromyalgia but 'chronic denervation' as would be seen in post-polio but I would not have had polio" - he did SFEMG which confirmed earlier muscle biopsy result for chronic denervation. There is no bladder involvement.
Could you please answer my questions:

Q1: What is my ‘muscle fatigue’ (see description above) called: is it weakness, fatigue, or exercise intolerance and is this typical of “chronic denervation” (to be more specific)?

Q2: Given that my mental fatigue has not abated in 5 years; my ‘exercise intolerance’ and muscle pain/fatigue is marginally worse should I pursue for other causes ie metabolic disorders?

Metabolic muscle disorders such as glycogen & lipid storage disorders & mitochondrial enzyme deficiencies are often linked to premature exercise intolerance. This is why I want to know what is the correct descriptor for my muscle condition (rapid fatigue) so I can clearly explain it to my doctor.
Thank you