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Table 2 Mapping overlap between myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) and d-lactic acidosis (d-la) symptoms

From: Examining clinical similarities between myalgic encephalomyelitis/chronic fatigue syndrome and d-lactic acidosis: a systematic review

ME/CFS International Consensus Criteria [1] d-la symptoms mapped to ME/CFS criteria
Matching Ambiguous/other
A. Postexertional neuroimmune exhaustion (compulsory) A. Lethargy/fatigue  
B. Neurological impairments (at least one symptom from 3 of the 4 categories)  B1. Neurocognitive impairments  B2. Pain  B3. Sleep disturbances  B4a. Neurosensory and perceptual and  B4b. Motor disturbances B1. Encephalopathy/Mental confusion/disorientation/dazed/Concentration difficulties/Slow processing and responding to questions/slow speech B2. Headaches/Muscle pain B3. Drowsiness/sleepiness/somnolence B4a. Blurred vision B4b. Weakness/hypotonic (lowered muscle tone)/flaccidity/impaired gait (staggering/wide/ataxic/unsteady/instability)/ataxia (movement and co-ordination difficulties)/impaired balance B1. Altered mental state/cortical dysfunction (e.g., disoriented to date, time, place and space)/delirium/blunted judgment/abnormal EEG B4a. Hallucinations (visual and auditory)/delusions/paranoid ideation B4b. Slowed cerebellar function/movement/dysiadochokinesia (difficulty performing rapid movement)/impaired reflexes/Neuropathy (fine motor coordination difficulties)/unable to grasp objects/Ptosis (eye drooping)/Asterixis (hand ‘flapping’/tremor)/Spasms: nystagmus (eye spasms)/opisthotonos (muscle spasms leading to hyperextended posture)/Bruxism
   Speech symptoms: Slurred and incoherent speech/dysarthria (speech pronunciation difficulties, weak muscles effecting speech)/thickened speech/ataxic speech (explosive—pauses between syllables)
   Consciousness: Altered/fluctuating/comatose/intermittent coma/stupor/induced sleep/depressed level of consciousness/obtunded/fluctuating from unrousable to alert
C. Immune, gastro-intestinal and genitourinary impairments (at least one symptom from 3 of the 5 categories)  C1. Flu-like symptoms  C2. Prone to viral infections  C3. Gastro-intestinal abnormalities: nausea, abdominal pain, irritable bowel syndrome, bloating  C4. Genitourinary symptoms  C5. Sensitivities to food, medication, odours or chemicals C3. Gastrointestinal symptoms*: Increased diarrhea/bowel movements Nausea/vomiting Diffuse abdominal pain  
D. Energy production/transportation impairments (at least 1 symptom)  D1. Cardiovascular: orthostatic intolerance (inability to tolerate an upright position), postural orthostatic tachycardia syndrome, palpitations, arrhythmias, hypotension, dizziness, pallor  D2. Respiratory: labored breathing, air hunger, fatigue of chest wall muscles  D3. Thermostatic instability: lowered body temperature, cold extremities, marked diurnal fluctuations, sweating, episodic feverishness  D4. Intolerance to temperature extremes D1. Inability to stand/sit upright/Tachycardia (rapid heart rate)/Respiratory arrhythmia/Hypotension/low blood pressure/Dizziness/Pallor D2. Breathing difficulties: hyperpnoea (deep breathing)/dyspnoea (shortness of breath)/tachypnea (rapid breathing)/Kussmaul (deep and laboured)/breathlessness/hyperventilation D3. Body temperature changes (high or low) D1. Bradycardia (slowed heart rate) D2. Respiratory acidosis and hypercarbic respiratory failure
Comorbid Mood and Behavioural Disturbances 1. Depressive symptoms 2. Anxiety symptoms 1. Unhappy/agitation/irritability 2. Anxiety Irrational/unusual/disturbed behavior/aggressive/hostile/abusive/combative/uncooperative behavior/euphoria/aloofness
Uncategorized d-la symptoms
   Metabolic acidosis
   Other abnormalities: dehydration/cravings (water, cigarettes)/excessive thirst Acute renal failure/hyperchloremic acidosis/liver dysfunction
  1. ME/CFS broad category B. Neurological impairments are highlighted as the primary focus of this review and to show three subcategories of delineation under ambiguous/other symptoms (i.e., in accordance with specific ICC criteria (B1 – B4), speech/language symptoms, and level of consciousness)
  2. * Gastro-intestinal symptoms associated with short bowel syndrome or the patient’s medical history were not included as symptoms of d-la. Only reports of a change in gastrointestinal symptoms were included
  3. ambiguous/other: symptoms that were not clearly identified as consistent with ME/CFS presentation (see Table 2 for detailed symptom delineation), d -la d-lactic acidosis, matching: mapped overlap between ME/CFS and d-la symptoms, ME/CFS myalgic encephalomyelitis/chronic fatigue syndrome