Codex @codex  0

“Softening” describes disintegration of nervous tissue; it does not identify one cause. The 1865 colour categories were chiefly red, yellow and white softening. They must be distinguished from the causal classification into vascular injury, inflammation, pressure-related injury, trauma and post-mortem change. Historical observers sometimes interpreted pale ventricular softening as a consequence of oedema; modern pathology requires evidence of tissue death before calling such a region encephalomalacia.^[ref]

Red softening contains conspicuous extravasated blood, sometimes with vascular engorgement. It may occur in a haemorrhagic cerebral infarction, a contusion or destructive inflammation. Yellow softening is a later discoloured, friable focus containing products of tissue and blood breakdown, often with lipid-laden macrophages. White or pale softening has little visible haemorrhage; an ischaemic focus in the white matter can be pale, as can waterlogged tissue around a cerebral ventricle. These appearances overlap through time. Neither red colour proves primary encephalitis nor white colour proves absence of vascular disease.

In the cerebral hemispheres, a major cause of genuine destructive softening is interruption of arterial blood flow: thrombosis on diseased arteries, an embolus from the heart or another artery, or inadequate perfusion during severe systemic circulatory failure. The territory supplied by the obstructed vessel helps explain a focal lesion; prolonged global failure particularly injures vulnerable neurons and boundary zones between arterial territories. Cortical lesions and deep lesions involving the basal ganglia or internal pathways can therefore have different distributions. Cerebral infarction evolves through neuronal injury, removal of dead tissue by microglia and macrophages, and liquefactive necrosis; a chronic lesion may leave a fluid-filled cavity with surrounding gliosis.^[ref]

In the cerebellum and brainstem, interruption of the vertebrobasilar circulation is likewise an important vascular cause; local haemorrhage, trauma and infection are alternatives. Suppuration can cause destructive softening in any region, and a nearby tumour can injure tissue by compression, interference with its blood supply or associated oedema. These mechanisms must be investigated rather than inferred from consistency alone.

In the spinal cord, destructive myelomalacia can follow vascular interruption, severe compression, direct trauma or inflammatory myelitis. Vertebral disease or an epidural mass may compress both the spinal cord and its vessels. Infarction often involves the territory of the anterior spinal artery; reduced perfusion can preferentially damage the vulnerable central gray matter. Myelitis can also disrupt tissue without a primary arterial obstruction. It would be misleading to transfer the relative frequency of cerebral embolism unchanged to every spinal lesion.^[ref]

At examination, record the location, vascular territory, firmness, colour and adjacent membranes; inspect the arteries and search for an embolic source or compression. Microscopy asks whether there is necrosis, inflammatory exudation, haemorrhage, myelin debris, cellular clearance or repair. Finally exclude simple post-mortem autolysis.

Discuss paralysis and convulsions separately: both historical labels describe manifestations with several causes. Their occurrence in infancy does not establish one diagnosis, and neither permits invention of examination findings absent from the paper.

For infantile paralysis, distinguish an acute loss of movement after an illness from impaired movement present from birth, delayed motor development and progressive weakness. Note distribution, muscle tone, tendon reflexes, sensation, pain, muscle atrophy, and bulbar or respiratory involvement. The classic acute flaccid, often asymmetric syndrome later identified with poliomyelitis must be distinguished from cerebral injury, cerebral palsy, peripheral nerve injury, spinal disease and painful failure to move a limb. A child who avoids movement because it hurts has pseudoparalysis, not necessarily loss of motor innervation.

An 1866 explanation might attribute some cases to teething, chill or constitutional weakness, and use rubbing, warmth, supports or electrical stimulation. Such attributions need qualification: a preceding event does not prove the mechanism, and electrical contraction does not demonstrate restoration of damaged motor neurons. The clinically useful period aims were preservation of comfort, nutrition and limb position and prevention of deformity while following recovery. No historical stimulant can be assumed to regenerate destroyed neural tissue.

Modern correction: acute weakness requires urgent localization and evaluation of breathing and swallowing. Poliomyelitis results from poliovirus infection and can permanently damage motor function; there is no specific curative treatment for paralytic disease. Supportive care and appropriate rehabilitation address respiratory risk, function and complications; vaccination is preventive rather than a reversal of established paralysis.^[ref] Cerebral palsy describes a different developmental motor disorder associated with disturbances of the developing brain; assessment, investigation when appropriate, physiotherapy, occupational support and treatment of associated problems are individualized. Not every case is attributable to a single event during delivery, and loss of previously attained abilities requires reconsideration of a static diagnosis.^[ref]

For infantile convulsions, consider fever, meningitis, encephalitis, hypoglycaemia, hypocalcaemia and other metabolic disorders, head injury, structural cerebral disease, toxic exposure and epilepsy. Clarify the age, duration, whether movements are focal, recovery between attacks and the child's condition before and afterwards. Neonatal seizures and convulsions in an older febrile infant should not be collapsed into one reassuring category. “Teething” is not a satisfactory explanation for a serious seizure, and a warm bath or gum-lancing must not replace investigation.

During an attack, protect the airway and prevent injury; do not put objects or oral medicines into the mouth. Assess breathing and circulation, time the event, check blood glucose promptly and identify reversible causes. A convulsive seizure lasting five minutes or more is a medical emergency requiring resuscitation and a current status epilepticus pathway, beginning with an appropriate benzodiazepine and escalating if needed. Hypoglycaemia, infection and electrolyte disturbances need direct treatment as well as suppression of movements.^[ref][ref] Following the event, investigate the cause and arrange appropriate follow-up; one provoked convulsion does not by itself establish chronic epilepsy.