What is the differential diagnosis for a patient presenting with shivering and diaphoresis (excessive sweating) of the head in a cool environment?

Differential Diagnosis: Shivering with Head Diaphoresis in Cool Environment

This presentation of shivering with localized head sweating in an air-conditioned room suggests autonomic nervous system dysfunction, and you must urgently evaluate for infection/sepsis, neurological disorders (particularly seizures or autoimmune encephalitis), thyroid dysfunction, or paradoxical thermoregulatory responses.

Immediate Life-Threatening Considerations

Infection/Sepsis

• Fever with infection commonly causes shivering even in cool environments, and profuse sweating (particularly of the head and neck) often accompanies the febrile response 1
• Check temperature immediately—if ≥38.0°C with shivering, sepsis must be ruled out with blood cultures and lactate 1
• Respiratory and wound infections are particularly common causes of this presentation 1

Neurogenic Fever

• Brain injury or hypothalamic dysfunction can cause fever without infection, presenting with shivering and diaphoresis 2
• This is a diagnosis of exclusion after ruling out sepsis 2

Neurological Causes (Critical to Consider)

Focal Seizures with Autonomic Manifestations

• Focal seizures can present exclusively as episodic sweating, chills, and shivering without motor symptoms 3
• The episodic nature is key—ask specifically about recurrent, stereotyped episodes 3
• EEG may show sharp and slow wave bursts in frontal regions; brain MRI may reveal chronic ischemic changes 3
• These patients respond to anticonvulsants like carbamazepine 3

Autoimmune Encephalitis

• Anti-LGI1 antibody encephalitis can present with acute hyperhidrosis as the primary manifestation of autonomic dysfunction 4
• Consider this in patients with new-onset, unexplained excessive sweating, particularly if other subtle neurological signs emerge 4
• Requires CSF analysis and autoimmune antibody panels 4

Endocrine/Metabolic Causes

Hyperthyroidism

• Obtain thyroid function tests (TSH, free T4) to evaluate for hyperthyroidism, which disrupts thermoregulation and causes heat intolerance with paradoxical shivering 5
• Patients may feel cold despite being in a cool environment due to altered temperature perception 5

Episodic Spontaneous Hypothermia with Hyperhidrosis

• Rare syndrome characterized by unprovoked hypothermia with profuse sweating and absent shivering despite symptomatic hypothermia 6
• Check core temperature—if hypothermic (<35°C) with sweating but no shivering, consider this diagnosis 6
• May respond to cyproheptadine (antiserotonergic agent), suggesting serotonergic dysfunction in hypothalamic thermoregulation 6

Paradoxical Thermoregulatory Response

Altered Hypothalamic Function

• Cooling of blood in the carotid artery by jugular venous blood can trigger shivering even when skin temperatures are maintained at thermoneutral levels (31-33°C) 7
• The hypothalamus responds to cooled arterial blood, not peripheral temperature 7
• This explains why patients can shiver in air conditioning despite having warm skin 7

Diagnostic Algorithm

Step 1: Vital Signs and Core Temperature

• Measure rectal or esophageal temperature (not oral/axillary) 8
• If febrile (≥38°C): Obtain blood cultures, CBC, lactate, urinalysis—treat as potential sepsis 1
• If hypothermic (<35°C): Consider episodic spontaneous hypothermia with hyperhidrosis 6

Step 2: Characterize the Episodes

• Are episodes recurrent and stereotyped? If yes, strongly consider focal seizures 3
• Is shivering present or absent? Absent shivering with hypothermia suggests hypothalamic dysfunction 6
• Is sweating generalized or localized to head/neck? Localized head sweating with systemic symptoms suggests autonomic dysfunction 4

Step 3: Initial Laboratory Workup

• TSH, free T4 (hyperthyroidism) 5
• CBC with differential, CRP, procalcitonin (infection) 1
• Basic metabolic panel, magnesium (electrolyte disturbances) 8
• Blood cultures if febrile 1

Step 4: Neurological Evaluation if No Infection Found

• EEG to evaluate for seizure activity (particularly frontal sharp waves) 3
• Brain MRI to assess for structural lesions, ischemic changes, or corpus callosum abnormalities 3, 6
• Consider autoimmune encephalitis panel (anti-LGI1, NMDA receptor antibodies) if presentation is acute and unexplained 4

Critical Pitfalls to Avoid

• Do not dismiss isolated sweating and shivering as benign without excluding serious underlying conditions 4
• Do not assume the patient is simply "cold" in air conditioning—this combination suggests dysautonomia 7
• Do not overlook focal seizures because motor symptoms are absent—autonomic seizures are easily missed 3
• Do not delay sepsis workup if fever is present—infection must be ruled out first 1
• Do not use benzodiazepines (like alprazolam) for symptomatic shivering—they cause hypotension and are not evidence-based for this indication 9

Symptomatic Management (After Excluding Emergencies)

If Infection is Ruled Out and Patient is Symptomatic

• Use layered clothing that can be adjusted regardless of ambient temperature 5
• Avoid extreme temperature environments; stay in moderate temperature zones 5
• For persistent shivering without fever: Consider meperidine 25-50 mg IV (most effective agent, stops shivering in nearly 100% within 5 minutes) 9
• Surface counterwarming of extremities (ears, palms, soles) reduces shivering threshold without sedation 8

When to Refer

• Refer to neurology if episodes are recurrent, stereotyped, or if EEG/MRI abnormalities are found 3
• Refer to endocrinology if thyroid dysfunction is confirmed 5
• Refer to infectious disease if sepsis workup is positive 1