obsolete myopathy of critical illness

Critical Illness Myopathy (CIM) was identified as a cause of prolonged weakness and is characterized by atrophy of type II muscle fibers and loss of thick myosin filaments [2][3]. This condition was previously referred to as CIM or ICU myopathy, and it was the most frequent myopathy affecting critically ill patients [2].

Traditional CIM demonstrates myosin loss, which is a hallmark feature of this condition. However, there are other subtypes of CIM, including fulminant acute necrotizing myopathy and cachectic myopathy [12]. These subtypes can have distinct pathophysiological processes and clinical presentations.

In the past, CIM was often described as an "acute acquired primary myopathy" characterized by critical illness, clinical signs of weakness, electrophysiological signs of myopathy, and evidence of primary myopathy with myosin loss [15].

It's worth noting that the term "Critical Illness Myopathy" is no longer commonly used in modern medical literature. Instead, the condition is often referred to as part of a broader category of neuromuscular disorders caused by severe illness, known as Critical Illness Associated Weakness (CIAW) [7].

Based on the provided context, it appears that there are several forms of myopathies associated with critical illness. However, I'll focus on the signs and symptoms of one specific type, which is Critical Illness Myopathy (CIM).

Common Signs and Symptoms:

• Muscle weakness: This is a hallmark symptom of CIM, particularly affecting the proximal muscles (those closer to the trunk) [8][10].
• Sensory preservation: Unlike some other forms of myopathies, CIM typically spares sensory function, meaning that patients may not experience numbness or tingling in their extremities [11][12].
• Muscle atrophy: As a result of prolonged immobility and muscle disuse, muscles may undergo atrophy (shrinkage) [8][10].

Additional Symptoms:

• Flaccid and symmetrical weakness: CIM often presents with diffuse flaccid and symmetrical weakness, affecting both sides of the body equally [4][6].
• Reduced or absent deep tendon reflexes: Patients with CIM may exhibit reduced or absent deep tendon reflexes, which can be a useful diagnostic clue [11].

Key Points:

• CIM is a common condition affecting skeletal muscles in intensive care units.
• Muscle weakness, sensory preservation, and muscle atrophy are key signs and symptoms of CIM.

References:

[4] Critical illness myopathy: further evidence from muscle-fiber excitability studies of an acquired channelopathy. Muscle Nerve. 2008;37:14–22. doi: 10.1002/mus.20884. [6] Haeseler G, Foadi N, Wiegand E, Ahrens J ... [8] Critical illness myopathy is a common condition affecting skeletal muscles in intensive care units, leading to prolonged mechanical ventilation and mortality. [10] Characterized by more proximal than distal weakness, sensory preservation, and atrophy depending on the duration of illness. Usually occurs in ... [11] Clinical features of CIM include diffuse flaccid and symmetrical weakness as well as reduced or absent deep tendon reflexes with preservation of sensory ...

Based on the provided context, it appears that there are several diagnostic tests that can be used to diagnose critical illness myopathy (CIM), a form of generalized weakness involving the muscles of the ICU-acquired weakness.

Electrophysiological Studies

• Nerve conduction studies and needle electromyography (EMG) are considered the gold standard for diagnosing CIM [5].
• These tests can help identify electrophysiological signs of myopathy, which is a key criterion for diagnosing CIM [14].

Muscle Biopsy

• Muscle biopsy is another diagnostic tool that can be used to diagnose CIM [4].
• The presence of primary myopathy with myosin loss on muscle biopsy is considered a key criterion for diagnosing CIM [14].

Other Diagnostic Tests

• Electromyography (EMG) and nerve conduction studies are theoretically sufficient for clinical diagnosis, but electrophysiological studies can be difficult to perform in critically ill patients [7].
• Muscle ultrasound may also be used as an initial evaluation tool for ICU-acquired weakness [9].

It's worth noting that the diagnostic criteria for CIM are divided into clinical and electrophysiological criteria, and muscle biopsy [8]. However, these tests should not be used in isolation to diagnose CIM, but rather as part of a comprehensive approach involving the presence of critical illness, clinical signs of weakness, and evidence of primary myopathy with myosin loss.

References:

[4] by B Rodriguez · 2022 · Cited by 15 — The current guidelines for diagnosis include clinical and electrophysiological criteria as well as a muscle biopsy, and allow diagnosis only at an advanced stage of the disease. [5] by T Plaut · 2022 · Cited by 17 — The gold standard for diagnosing critical illness neuropathy remains electrodiagnostic testing, which includes nerve conduction studies and needle electromyography (EMG). [7] by C Zhou · 2014 · Cited by 207 — Electromyography and nerve conduction studies are theoretically sufficient for clinical diagnosis[72]. However, electrophysiological studies are difficult to perform in critically ill patients. [8] by B Rodriguez · 2024 — The diagnostic criteria for CIM are divided into clinical and electrophysiological criteria, and muscle biopsy. See Latronico and Bolton (2011) for a detailed description of the diagnostic criteria. [14] For example, in CIM, which is characterized as an acute acquired primary myopathy, diagnostic criteria are based on a comprehensive approach involving the presence of critical illness, clinical signs of weakness, electrophysiological signs of myopathy, and evidence of primary myopathy with myosin loss (Latronico and Bolton, 2011).

Based on the provided context, it appears that you are looking for information on the differential diagnosis of a specific type of myopathy associated with critical illness.

The search results suggest that there are several conditions that can cause weakness in patients with critical illness, including:

• Critical Illness Myopathy (CIM)
• Critical Illness Polyneuropathy (CIP)
• Intensive Care Unit-Acquired Weakness (ICUAW)

According to the context [10], differential diagnosis is usually obvious for these conditions, as they are typically a cause of ICU admission and not a complication of critical illness during ICU stay. Conversely, CIW is commonly diagnosed in patients with persisting critical illness who have normal muscle strength at ICU admission.

The context also mentions that CIM can be differentiated from CIP based on the presence of myosin loss [1][3][38]. Additionally, it notes that CIM is a heterogenous entity with differing pathologic subtypes, including traditional CIM, fulminant acute necrotizing myopathy, and cachectic myopathy [13].

In terms of differential diagnosis, the context suggests that the following conditions should be considered:

• Critical Illness Myopathy (CIM)
  • Traditional CIM: characterized by myosin loss
  • Fulminant acute necrotizing myopathy: marked elevation in creatinine kinase and muscle damage
  • Cachectic myopathy: associated with weight loss and muscle wasting
• Critical Illness Polyneuropathy (CIP): a condition that affects the nerves, leading to weakness and paralysis

It's worth noting that the context also mentions that ICUAW is a term used to describe patients who have clinically detected weakness with no plausible cause other than critical illness [11]. However, this term is not as specific as CIM or CIP, and further investigation would be needed to determine the underlying cause of weakness in these patients.

References:

[1] by J Khan · 2008 · Cited by 122 [3] by J Khan · 2008 · Cited by 122 [10] [13]