**Question:** Schaffer's sign is seen in -

A. Brain death
B. Cardiac arrest
C. Traumatic brain injury
D. Subarachnoid haemorrhage

**Core Concept:**
Schaffer's sign is a clinical sign described by Sir William Schaffer in 1930, which is used to diagnose subarachnoid haemorrhage (SAH). SAH is a type of stroke caused by bleeding into the subarachnoid space, the space between the inner and outer layers of the brain's protective membranes (the meninges). It is a severe neurological emergency that requires immediate medical attention and intervention.

**Why the Correct Answer is Right:**
Schaffer's sign is a useful clinical sign to detect SAH because it is associated with the increased pressure within the subarachnoid space due to bleeding. When present, it is characterized by:

1. **Generalized tonic-clonic seizures:** These seizures occur due to the increased pressure on the brainstem, causing alterations in brainstem reflexes.
2. **Absence of the corneal and pupillary reflexes:** The pressure on the brainstem disrupts the neural pathways responsible for these reflexes.

**Why Each Wrong Option is Incorrect:**
1. **Brain death:** Schaffer's sign is not observed in brain death because the brainstem reflexes are absent in this condition. Brain death refers to the irreversible loss of brain function, including the inability to maintain vital functions like breathing and circulation.
2. **Cardiac arrest:** Schaffer's sign is not present in cardiac arrest as this condition is characterized by the complete loss of circulation and brain perfusion, leading to loss of brain function and absence of brain reflexes. Cardiac arrest is a life-threatening emergency that requires immediate intervention, whereas Schaffer's sign is a sign of subarachnoid haemorrhage.
3. **Traumatic brain injury:** Traumatic brain injury (TBI) occurs due to external mechanical force, whereas Schaffer's sign is specific to subarachnoid haemorrhage caused by bleeding into the subarachnoid space. Traumatic brain injury may present with other neurological deficits, but Schaffer's sign is not a consistent finding in traumatic brain injury patients.
4. **Corneal and pupillary reflexes impairment:** Corneal and pupillary reflexes are impaired in many neurological conditions, but Schaffer's sign is specific to subarachnoid haemorrhage. It is crucial to differentiate Schaffer's sign from other neurological deficits due to various conditions, as it guides the appropriate management and diagnosis.

**Clinical Pearl:** Schaffer's sign is a valuable clinical tool in patients presenting with sudden-onset altered mental status, focal neurological deficits, or seizures, which may suggest subarachnoid haemorrhage. Immediate neurosurgical consultation and further diagnostic tests (CT scan or MRI) are essential in confirming the diagnosis.

**Core Concept:** Schaffer's sign is a clinical sign that highlights the disruption of brainstem reflexes due to increased pressure in the subarachnoid space