Trichorrhexis Nodosa

A hair shaft defect in which focal nodes of cortical fibre separation appear along the shaft. The cortex splits and the fibres fray, like two brooms pushed together at the ends, and the hair breaks at these points.

• Types:
  • Proximal (acquired, usually in people of African ancestry): nodes near the scalp, from chemical treatments, tight styling and trauma, causing breakage.
  • Distal (acquired, the most frequent in those of European and Asian ancestry): nodes near the ends of long hair, from repeated mechanical and chemical stress.
  • Localised: in a single area, from rubbing or scratching.
  • Congenital or inherited: starts in infancy.
• Acquired causes: vigorous brushing and combing, towel drying, hair ties, heat (flat irons, blow dryers, curling), chemical relaxers, perms, bleaching and dyes, ultraviolet damage, and trichotillomania. Nutritional and systemic causes: iron deficiency, zinc, copper and protein deficiency, essential fatty acid deficiency, hypothyroidism, hypoparathyroidism and anorexia nervosa.
• Congenital causes: argininosuccinic aciduria (argininosuccinate lyase deficiency), Menkes disease (copper transport defect, with kinky hair and neurodegeneration), trichothiodystrophy (sulphur deficient brittle hair), citrullinaemia type 1, Netherton syndrome, and ectodermal dysplasias.
• Acquired disease is far more common than congenital disease. A normal baby with brittle hair and developmental delay or seizures needs metabolic review.

• Dry, dull, brittle hair that breaks easily, with short and uneven length that fails to grow. Small, white or pale nodes along the shaft, visible with the naked eye or a hand lens.
• In proximal disease, hair breaks a few centimetres from the scalp, with a short stubble like appearance. In distal disease, the ends are frayed and split (trichoptilosis).
• The scalp is normal. Eyebrows, eyelashes and beard can be affected.
• Congenital forms: sparse brittle hair from infancy, with systemic features:
  • Argininosuccinic aciduria: hyperammonaemia, vomiting, lethargy, seizures, hepatomegaly and developmental delay.
  • Menkes disease: pale, kinky, steely hair, hypotonia, seizures, failure to thrive, and connective tissue defects.
  • Trichothiodystrophy: brittle sulphur deficient hair, ichthyosis, short stature, intellectual disability and photosensitivity.
• Differential diagnosis: trichorrhexis invaginata (bamboo hair in Netherton syndrome), monilethrix, pili torti, tinea capitis, alopecia areata, traction alopecia, trichotillomania, telogen effluvium, and hair damage from chemicals.
• Complications: hair loss, cosmetic distress, inability to grow long hair, and, in congenital forms, the complications of the underlying disease.

• Light microscopy of plucked or cut hairs: a nodal swelling with fraying fibres, and an appearance of two paintbrushes pressed together. Polarised light microscopy shows brush like ends. Dermoscopy shows white nodes and breaks. Scanning electron microscopy shows detail of the fraying.
• Clinical assessment for acquired causes: hair care history, chemical and heat use, and trauma.
• Laboratory screening in those with no obvious mechanical cause: full blood count, ferritin, zinc, copper, caeruloplasmin, thyroid function, calcium, parathyroid hormone, and albumin.
• In infants and children with brittle hair and neurological or systemic features: plasma ammonia, plasma amino acids and urinary orotic acid (argininosuccinic aciduria shows raised argininosuccinate and citrulline), plasma copper and caeruloplasmin (low in Menkes disease), sulphur content of hair (trichothiodystrophy), and genetic testing.
• Rule out eating disorders when weight loss and brittle hair coexist.

• Hair care to prevent mechanical and chemical damage, which is the key to treating acquired disease:
  • Stop or reduce chemical relaxers, perms, bleaching and dyes. Leave at least 8 to 12 weeks between treatments, and do not overlap on previously treated hair.
  • Limit heat styling (blow dryer on a cool setting, flat irons at less than 150 C), and use a heat protectant.
  • Wash with a mild shampoo and use conditioner every wash, and apply a leave in conditioner or an oil to the ends (silicone, argan or similar).
  • Detangle gently from the ends upward with a wide toothed comb on damp hair, and avoid vigorous brushing and towel drying (blot with a soft cloth or microfibre).
  • Use satin or silk pillowcases and covers, avoid tight bands and clips, and avoid tight styles.
  • Trim damaged ends every 6 to 8 weeks, and allow the damaged hair to grow out.
• Correct underlying deficiencies and disease:
  • Iron deficiency: ferrous sulphate 200 mg (65 mg elemental iron) orally once daily or on alternate days, continued for 3 months after the anaemia and ferritin normalise (target ferritin above 50 to 70 ng/mL).
  • Zinc deficiency: zinc sulphate 220 mg (50 mg elemental) orally once daily for 3 months, then recheck levels. Long courses cause copper deficiency.
  • Hypothyroidism: levothyroxine 1.6 micrograms/kg per day, adjusted to thyroid stimulating hormone at 6 to 8 weeks.
  • Protein and energy deficiency, eating disorders: dietary rehabilitation with specialist support.
• Topical therapy: conditioners with silicone or hydrolysed proteins temporarily smooth the cuticle and reduce breakage. Biotin 2.5 mg daily has limited evidence in hair disorders, and it interferes with troponin and thyroid immunoassays, so stop it 2 to 3 days before blood tests.
• Congenital disorders (specialist care):
  • Argininosuccinic aciduria: dietary protein restriction, arginine supplementation, nitrogen scavengers (sodium phenylbutyrate or glycerol phenylbutyrate), and emergency management of hyperammonaemia, under a metabolic team.
  • Menkes disease: early copper histidinate injections (subcutaneous, started in the first weeks of life) can improve outcome in some patients (evidence limited), and the condition is life limiting.
  • Trichothiodystrophy: sun protection, multidisciplinary care and genetic counselling.
• Special groups:
  • Children: gentle hair care, and a low threshold to investigate for congenital disease when brittle hair is accompanied by developmental, neurological or growth problems.
  • Pregnancy: hair care changes and nutritional correction. Avoid high dose zinc and vitamin A supplements.
  • Elderly: check for iron, zinc and thyroid disease, and for medicine effects.
• Follow up: review at 3 months for hair growth, and again at 6 months. Hair regrowth takes 6 to 12 months to show. Refer to dermatology for unclear causes, and to paediatrics and metabolic services for suspected congenital disease.